Liquid Fuels: Types, Properties and Production : Types., Properties and Production [1 ed.] 9781614705130, 9781614704355

Citation preview

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved. Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved. Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

ENERGY SCIENCE, ENGINEERING AND TECHNOLOGY

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

LIQUID FUELS: TYPES, PROPERTIES AND PRODUCTION

No part of this digital document may be reproduced, stored in a retrieval system or transmitted in any form or by any means. The publisher has taken reasonable care in the preparation of this digital document, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained herein. This digital document is sold with the clear understanding that the publisher is not engaged in rendering legal, medical or any other professional services.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

ENERGY SCIENCE, ENGINEERING AND TECHNOLOGY Additional books in this series can be found on Nova‘s website under the Series tab.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Additional E-books in this series can be found on Nova‘s website under the E-book tab.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

ENERGY SCIENCE, ENGINEERING AND TECHNOLOGY

LIQUID FUELS: TYPES, PROPERTIES AND PRODUCTION

DOMENIC A. CARASILLO Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

EDITOR

Nova Science Publishers, Inc. New York Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Copyright © 2012 by Nova Science Publishers, Inc. All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic, tape, mechanical photocopying, recording or otherwise without the written permission of the Publisher. For permission to use material from this book please contact us: Telephone 631-231-7269; Fax 631-231-8175 Web Site: http://www.novapublishers.com NOTICE TO THE READER The Publisher has taken reasonable care in the preparation of this book, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained in this book. The Publisher shall not be liable for any special, consequential, or exemplary damages resulting, in whole or in part, from the readers‘ use of, or reliance upon, this material. Any parts of this book based on government reports are so indicated and copyright is claimed for those parts to the extent applicable to compilations of such works.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Independent verification should be sought for any data, advice or recommendations contained in this book. In addition, no responsibility is assumed by the publisher for any injury and/or damage to persons or property arising from any methods, products, instructions, ideas or otherwise contained in this publication. This publication is designed to provide accurate and authoritative information with regard to the subject matter covered herein. It is sold with the clear understanding that the Publisher is not engaged in rendering legal or any other professional services. If legal or any other expert assistance is required, the services of a competent person should be sought. FROM A DECLARATION OF PARTICIPANTS JOINTLY ADOPTED BY A COMMITTEE OF THE AMERICAN BAR ASSOCIATION AND A COMMITTEE OF PUBLISHERS. Additional color graphics may be available in the e-book version of this book.

Library of Congress Cataloging-in-Publication Data

Liquid fuels : types, properties, and production / editor, Domenic A. Carasillo. p. cm. Includes index. ISBN 978-1-61470-513-0 (E-Book) 1. Liquid fuels. I. Carasillo, Domenic A. TP343.L6788 2011 662'.669--dc23 2011023236

Published by Nova Science Publishers, Inc. †New York Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

CONTENTS

Preface Chapter 1

Chapter 2

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Chapter 3

vii Ultradeep Desulfurization of Liquid Fuels by Adsorption under the Ambient Conditions: Active Sites and Molecular Mechanisms Alexander Samokhvalov An Analysis of Coal Mine Methane Emissions: Available and Emerging Utilization or Mitigation Technologies Gökhan Aydin, İzzet Karakurt and Kerim Aydiner High Yield Biofuel Production from Vegetable Oils with Supercritical Alcohols R. A. Usmanov F. M. Gumerov, F. R. Gabitov, Z. I. Zaripov, F. N. Scshamsetdinov, and I. M. Abdulagatov2

1

47

99

Chapter 4

Polymer Wastes Pyrolysis for Liquid Fuel Production Miguel Miranda, Filomena Pinto and I. Gulyurtlu

147

Chapter 5

Biofuel Production from Castor Seed Oil Hemant Y. Shrirame and N. L. Panwar

169

Chapter 6

195Characterization of Multifuel Eco-Blend (Diesel– Biodiesel–Bioethanol) for Unmodified CI Engines Laurencas Raslavičius and Žilvinas Bazaras

Chapter 7

Productionof Renewable Liquid Fuels Using Different Fuel Processing Methods N. R. Banapurmath, V. S. Yaliwal, R. S. Hosmath, Y. H. Basavarajappa, N. M. Girish, A. V. Tumbal, and P. G. Tewari

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

195

219

vi Chapter 8

Chapter 9

Contents Ethanol from Biomass: Application to the OlivePruning Debris Juan Francisco García and Javier García Liquid Fuel for Nuclear Energy: The Molten Salt Fast Reactor (MSFR) Concept Sylvie Delpech, Elsa Merle-Lucotte, Daniel Heuer and Cyrine Slim

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Index

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

239

255

283

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

PREFACE Liquid fuels are those combustible or energy-generating molecules that can be harnessed to create mechanical energy. Most liquid fuels, in widespread use, are or derived from fossil fuels such as gasoline, diesel, kerosene, alcohols, and hydrogen. In this book, the authors present topical research in the study of the types, properties and production of liquid fuels. Topics discussed include ultradeep desulfurization sorbents for liquid fuels; coal mine methane emission mitigation technologies; high yield biofuel production from vegetable oils with supercritical alcohols; polymer waste pyrolysis for liquid fuel production; liquid biofuel production made from castor seed oil and production of renewable liquid fuels using different fuel processing methods. Chapter 1 - Desulfurization of liquid fuels is the crucial requirement of the cleaner air and energy-efficient operation of internal combustion (IC) and diesel engines and turbines. The projected ―hydrogen economy‖ will require the ―sulfur-free‖ hydrogen to be produced from liquid hydrocarbon fuels via the ultradeep ( 2.5%) Esterification is done as a pretreatment step to the transesterification procedure when the FFA content is higher then 2.5%. In practice, it is a bit more complicated to implement then transesterification. A byproduct of the process is water, which impedes the reaction. As there is more FFA in the oil, more methanol percentage wise must be added to compensate for the water. To overcome this, industrial producers use counter current reactors that enable a continuous flow of high FFA oil in and water out.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

7. PROPERTIES OF BIODIESEL Generally, the properties of biodiesel and especially its viscosity and ignition properties are similar to the properties of fossil diesel. Although the energy content per liter of biodiesel is about 5 to 12 % lower than that of diesel fuel, biodiesel has several advantages. For example the cetane number and lubricating effect of biodiesel, important in avoiding wear to the engine, are significantly higher. Therefore the fuel economy of biodiesel approaches that of diesel. Additionally, the alcohol component of biodiesel contains oxygen, which helps to complete the combustion of the fuel. The effects are reduced air pollutants such as particulates, carbon monoxide, and hydrocarbons. Since biodiesel contains practically no sulfur, it can help reducing emissions of sulfur oxides [28]. Biodiesel is sensitive to cold weather and may require special anti-freezing precautions, similar to those taken with standard diesel. Therefore winter compatibility is achieved by mixing additives, allowing the use down to minus 20 °C. Another problem is that biodiesel readily oxidizes. Thus long-term storage may cause problems, but additives can enhance stability. Biodiesel also has some properties similar to liquid fuels are easy for transport, and can be handled with relative ease. Also they are relatively easy to use for all engineering applications, and home use. Biodiesel are also used most popularly in Internal Combustion engines. Some technically important properties are: flash point, Gross calorific value, kinematic viscosity, density, Acid value, Free fatty acid content, etc.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

184

Hemant Y. Shrirame and N. L.Panwar

7.1. Properties of Raw Castor (Ricinus Communis) Oil and Its Methyl Ester Different fuel properties of castor oil, castor oil methyl ester and diesel were determined as per procedure and are presented in Table 7. The castor methyl ester was compared to fossil diesel. The table shows the high viscosity and flashpoint of castor methyl ester. It shows further, that the properties of castor methyl ester were very similar to fossil diesel.

7.1.1. Density Density is the weight per unit volume. Oils that are denser contain more energy. For example, petrol and diesel fuels give comparable energy by weight, but diesel is denser and hence gives more energy per litre. Density is measured by the standard test procedure of Bureau of Indian Standards (IS 1448-1970). Density of castor (Ricinus communis) oil and its methyl ester were calculated using the density bottle which is shown in plate 4. Castor oil, before transesterification has a density of 0.956-0.963 g/ml (@ 20 oC). The conversion into methyl esters decreases the density by a small extent; about (0.913 g/ml) is quite close to that of diesel (0.830 g/ml). The density of castor methyl ester is 1.1 times that of diesel where as density of castor oil is 1.15 times of diesel. While the castor methyl ester has a density somewhat higher than petro-diesel, this is unlikely to be a bottleneck as the difference is not significant.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

where, d = density of oil, g/ml m2 = Mass of density bottle plus oil, g m1 = Mass of density bottle, g Table 7. Fuel properties of plant oil and their biodiesel Properties Density, g/ml (@ 20 oC). Kinematic viscosity, cS@ 38 o C Gross calorific value, MJ/ kg Flash point, oC Acid value, mg KOH/g Free fatty acid content, per cent (%)

Standard Code IS 14481970 IS 14481970 IS 13591959 IS 14481970

Titration

Instrument

Specifications

Density bottle Redwood viscometer No.1 Bomb calorimeter Pensky Martens apparatus

50 ml Capacity IP 12

Burette

12/16 T and BS 1016 IP 34

---

Castor oil

CME

Diesel

0.96

0.913

0.830

226.82

8.50

5.80

36.20

39.16

46.22

317

149

47

1.642

1.008

0.00

1.43

0.27

0.00

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Biofuel Production from Castor Seed Oil

185

7.1.2. Kinematic Viscosity Viscosity refers to the thickness of the oil, and is determined by measuring the amount of time taken for a given measure of oil to pass through an orifice of a specified size. Viscosity affects injector lubrication and fuel atomization. Fuels with low viscosity may not provide sufficient lubrication for the precision fit of fuel injection pumps, resulting in leakage or increased wear. Fuel atomization is also affected by fuel viscosity. Diesel fuels with high viscosity tend to form larger droplets on injection which can cause poor combustion, increased exhaust smoke and emissions. Kinematic viscosity is measured as per standard test procedure of Bureau of Indian Standards (IS 1448-1970). Kinematic Viscosity is the resistance to flow of a fluid under gravity. Redwood Viscometer No.1 (Khera instrument Pvt. Ltd., Azadpur, Delhi) (see plate 5) was used to determine the kinematic viscosity of raw castor (Ricinus communis) oil and its methyl ester. The time required to flow 50 ml oil having temperature of 38 oC was measured. The kinematic viscosity of raw castor (Ricinus communis) oil and its methyl ester were calculated as,

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

where, Vk = kinematic viscosity of oil, cS t = time of flow, s It is seen that the kinematic viscosity of castor oil is higher than diesel. Kinematic viscosity of castor oil is 226.82 cS @ 38 oC. Kinematic viscosity of castor oil methyl ester is 8.50 cS @ 38 oC, which is 1.46 times that of diesel. Hence kinematic viscosity of castor methyl ester is quite comparable with the diesel.

Plate 4. Density bottle.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

186

Hemant Y. Shrirame and N. L.Panwar

Plate 5. Redwood Viscometer No.1.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

7.1.3. Gross Calorific Valu Gross calorific Value or Heat of Combustion, is the amount of heating energy released by the combustion of a unit value of fuels. A Bomb Calorimeter (Khera instrument Pvt. Ltd., Azadpur, Delhi) is shown in plate 6 consisting of a strong cylindrical stainless steel bomb in which the combustion of fuel takes place was used for the study. Bomb Calorimeter measures the amount of heat generated when a specific quantity of matter is burnt in a sealed chamber (Bomb) in an atmosphere of pure oxygen gas. 7.1.4. Bureau of Indian Standards (IS: 1359-1959) The gross calorific value of the castor methyl ester, diesel and its blends B05, B10, B20 (05 per cent Castor methyl ester and 95 per cent diesel (B05), 10 per cent castor methyl ester and 90 per cent diesel (B10), 20 per cent Castor methyl ester and 80 per cent diesel (B20)) were determined using bomb calorimeter. A weighed quantity (1 ml.) of the sample was burnt in presence of the oxygen (Normally filled at a pressure of 25 kg/cm2 in the bomb calorimeter). The stirrer driven by a motor is switched on so as to keep the temperature of whole mass of water uniform. The electrodes on the bomb are connected to the electrical unit providing 6 volts for firing out the fuse wire so as to start the ignition in the bomb. Due to the combustion of the fuel, heat is liberated and the temperature of the water surrounding the bomb starts rising. The amount of rise in temperature of the water in the calorimeter is noted down when the temperature becomes constant. This rise in temperature is due to combustion of the fuel and it is used for determination of the calorific value of that fuel. The gross calorific value was then calculated from the weight of the sample and the rise in the temperature by using following formula. Before actual experiment on fuel, water equivalent of the bomb was measured by burning a known mass of benzoic acid with a known mass of water (1.9 lit.) in the calorimeter and the temperature rise was measured. Water equivalent of bomb calorimeter was calculated by the following equation.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Biofuel Production from Castor Seed Oil

187

The calorific value was calculated by the same equation using following equation

CV f  where, W mBA ∆TBA CW CVBA CVf mf ∆Tf

(1.6  W )  CW  T f mf = Water equivalent of the bomb calorimeter = Mass of benzoic acid, kg = Temperature rise in benzoic acid, oC = Specific heat of water, (4.184 kJ/kg K) = Calorific value of benzoic acid, (26460 kJ/kg) = Higher calorific value of Fuel, (kJ/kg) = Mass of fuel, kg = Rise in temperature, (oC)

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

It is seen that oil had lower gross calorific value compared to that of diesel. The gross calorific value of castor methyl ester (39.16 MJ/kg) and castor oil (36.20 MJ/kg) is quite low (46.22 MJ/kg) as compared to that of diesel.

7.1.5. Flash Point The flash point temperature of castor methyl ester is the minimum temperature at which the fuel will ignite (flash) on application of an ignition source. Flash point varies inversely with the fuel‘s volatility. Minimum flash point temperatures are required for proper safety and handling of fuel‘s. Flash point is measured by the standard test procedure of Bureau of Indian Standards (IS 1448-1970). Flash point was taken as the lowest temperature at which the flame caused the above sample ignites momentarily. Pensky-Martens Apparatus (Aimil Instrumentation, Bangalore) (Electrically Heated) AIM-508 flash point closed cup apparatus were used to measure the flash point of raw castor (Ricinus communis) oil and its methyl ester which was shown in Plate 7. The temperature was noted at which vapor caused above the oil ignite momentarily.

Plate 6. Oxygen Bomb Calorimeter. Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

188

Hemant Y. Shrirame and N. L.Panwar

Plate 7. Pensky-Martens Closed cup apparatus.

It is observed that the flash point of castor methyl ester is lower than that of its oil. The flash point of castor oil is 317 oC while the flash point of castor methyl ester is 149 oC. But the castor methyl esters have much higher flash point than the diesel (47 oC). The higher flash point of methyl ester than diesel is attributed to their longer carbon chain.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

7.1.6. Acid Value Acid value is the number of milligram of KOH to neutralize the free acid present in 1 g of oil. Acid value of raw Castor (Ricinus communis) oil and its methyl ester were calculated as follows

where, Wu = Weight of oil taken, g It is observed that the acid value of castor oil is higher (1.642 per cent). On esterification the acid value reduces drastically and acid value of castor methyl ester is 1.008 per cent. Which is zero per cent in case of diesel.

7.1.7. Free Fatty Acid Content A 10 g of oil is titrated with aqueous solution of 0.1 N solution of NaOH. The percent free fatty acid of raw castor (Ricinus communis) oil and its methyl ester were calculated as follows (Dara, 1999), where, Vn = Volume of NaOH used, ml N = Normality of NaOH M = Molecular weight of NaOH Wu = Weight of oil, g.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Biofuel Production from Castor Seed Oil

189

At elevated temperatures, fatty acids react with metal parts and fatty acid metal can be introduced into the engine cylinder and can increase wear. The per cent of free fatty acid in castor oil is 1.642 which is not so high, which could interfere with conversion and recovery of methyl ester. On esterification the values of FFA reduced drastically and FFA of castor oil methyl ester is 1.008 per cent. The value of free fatty acid content of diesel oil is zero.

8. EFFECT OF DIFFERENT BLENDS ON DENSITY AND CALORIFIC VALUE OF CASTOR METHYL ESTER The density and calorific value of methyl ester blends with diesel are depicted in Table 8. It is observed that the density of B05 (0.835 g/ml) is quite close to that of diesel (0.830 g/ml). The density of B05 is 1.00 times that of diesel. Similarly it is seen that B05 had lower gross calorific value compared to that of diesel. The gross calorific value of B05 (45.87 MJ/kg) is quite low (46.22 MJ/kg) as compared to that of diesel. Table 8. Variation of Density and Calorific value with blends Oil Diesel

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Castor

Biodiesel blends B0 B05 B10 B20

Density (g/ml) 0.830 0.835 0.839 0.849

Calorific value (MJ/kg) 46.22 45.87 45.52 44.81

Figure 4. Effect of different blends on density and calorific value of castor methyl ester.

9. PERFORMANCE AND EMISSION TEST OF CASTOR METHYL ESTER ON SINGLE CYLINDER DIESEL ENGINE TEST RIG Using different combinations of castor methyl ester with diesel, test trials were carried out for engine performance on VCR engine test setup single cylinder, four stroke diesel engine test rig (Computerized) product code-234. Effect of different combinations i.e. 100 per cent diesel oil (B0), 05 per cent Castor methyl ester and 95 per cent diesel (B05), 10 per cent castor methyl ester and 90 per cent diesel (B10), 20 per cent castor methyl ester and 80 per

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

190

Hemant Y. Shrirame and N. L.Panwar

cent diesel (B20) evaluated by conducting fuel consumption and power tests as per EMA standard test procedure. The setup for the study consists of single cylinder, four stroke, variable compression ratio (VCR) diesel engine connected to eddy current type dynamometer for loading (see Plate 8). The detailed specifications of the engine used are given in Table 9. Windows based Engine Performance Analysis Software Package ‗‗Enginesoft‖ was taken for on line performance evaluation. The NOx emission by the combustion of biodiesel was measured by online flue gas analyser. The tests were conducted at the rated speed of 1500 rpm at different loads. The engine was started with standard diesel fuel and warmed up. The warm up period ends when cooling water temperature is stabilized. Then fuel consumption, brake power, brake specific fuel consumption, brake specific energy consumption, brake thermal efficiency and exhaust gas temperature were measured. Same procedures were repeated for different blends of castor methyl ester.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Table 9. Specification of the engine used Make and model

Kirloskar diesel engine

General details

4-Stroke, water cooled, variable compression ratio engine, compression ignition

Number of cylinder

Single cylinder

Bore

87.5 mm

Stroke

110 mm

Swept volume

661 cc

Rated output

3.5 kW at 1500 rpm

Compression ration

17.5

Rated speed

1500 rpm

Temperature sensor

RTD PT 100 and K-type thermocouple

Load indicator

Digital, range 0–490.5 kN

Dynamometer

Type – eddy current, water cooled

Load sensor

Strain gauge load cell

Fuel flow transmitter

DP transmitter

Air flow transmitter

Pressure transmitter

Rotameter

Pressure transmitter

The engine performance was analysed with different blends of biodiesel and was compared with mineral diesel. It was concluded that the lower blends of biodiesel increased the break thermal efficiency and reduced the fuel consumption. The exhaust gas temperature increased with increasing biodiesel concentration. The results proved that the use of biodiesel (produced from castor seed oil) in compression ignition engine is a viable alternative to diesel.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Biofuel Production from Castor Seed Oil

191

Plate 8. Variable compression ratio (VCR) engine test setup.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

9.1. Emission Test The emission parameters during the test included CO, CO2, NOX, O2, and smoke density. The relationship between exhaust gases (CO, CO2, NOX, O2, and smoke density) with change in load and time of operation. The emission test was carried out at 20 min of interval at each load for different blends with the help of exhaust gas analyzer. The exhaust gas analyzer was calibrated and the readings were taken at 2 h of engine operation by inserting exhaust gas analyzers probe in exhaust outlet for each blend. In the initial inception, the engine was started with pure diesel fuel and warmed up. The warming period ends when the cooling water temperature is stabilised. Then, the exhaust gas temperature and different exhaust emissions like CO2, CO and NOx, smoke density, O2 and exhaust gas temperature were measured at a rated speed. A similar procedure was repeated for the CME blends B5, B10 and B20.

9.2. Carbon Monoxide (CO) Emissions A general trend that CO emissions decrease when diesel fuel is substituted with biodiesel. All the blends generally produce a low amount of CO emissions at a light load and give more emissions at higher load conditions. Biodiesel has about 11% of O2 content in it; this helps in the complete combustion of the fuel. Hence, the CO emission level decreases with an increasing biodiesel percentage in the fuel. In the case of B0, the CO emission is higher than that of the biodiesel blends. The reduction of the CO at a maximum load (145.28 kN) in B05, B10 and B20 averaged 13.75%, 25.02% and 28.79%, respectively, compared to diesel (B0).

9.3. Carbon Dioxide (CO2) Emissions The CO2 emissions increased with an increase in the load, as expected. The biodiesel blends emit low amounts of CO2 in comparison with B0. B20 emits a larger amount of CO2 compared to B0. A bigger amount of CO2 in the exhaust emissions is an indication of the

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

192

Hemant Y. Shrirame and N. L.Panwar

complete combustion of fuel. This supports the higher value of exhaust gas temperature. The main difference in ester-based fuel and diesel is the O2 content and cetane number. Since ester-based fuel contains a small amount of O2 and that acts as a combustion promoter inside the cylinder, it results in better combustion for B05 than B0. The combustion of fossil fuel produces CO2, which gets accumulated in the atmosphere and leads to many environmental problems. The combustion of biofuels also produces CO2, but crops readily absorb these and, hence, the CO2 level is kept in balance [29-31].

9.4. Nitrogen Oxide (Nox) Emissions It is well known that vegetable-based fuels contain a small amount of nitrogen. This contributes towards NOx production. In the case of B10, the NOx emission is lower than that of B0. The NOx concentration increased with the increase in the load and attains maximum at maximum load for all blends. In the case of B0, B05, B10 and B20, the recorded emissions were 683, 686, 638 and 694 ppm, respectively, for the 145.29 kN load. NOx emissions are dependent on engine combustion chamber temperatures which, in turn, are indicated by the prevailing exhaust gas temperature. With the increase in the value of the exhaust gas temperature, the NOx emissions have also increased. That is why biodiesel-fuelled engines have the potential to emit more NOx compared to diesel-fuelled engines [32].

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

9.5. Oxygen (O2) Emissions The average value of O2 emissions of the engine operation of each blend decrease with an increase in load conditions. This drop may be attributed to O2 having been consumed during the combustion process.

9.6. Smoke Density The smoke from the engine is a function of engine load, engine performance test smoke density increases with an increase in the applied load. Different biodiesel blends produce less smoke compared to diesel for same load conditions. During the test, it was found that B10 gave less smoke density compared B5 and B20. The smoke density of B10 at a 145.28 kN load is about 51.3% compared to 56.4% in B0.

CONCLUSIONS The vegetable oil-based fuel production is very attractive for developing countries like India. Vegetable oils are a renewable and potential inexhaustible source of energy with an energetic content close to diesel fuel. In addition to being available locally, renewable and cheap, biodiesel can make a good substitute for diesel fuel. The biodiesel is found to burn

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Biofuel Production from Castor Seed Oil

193

more efficiently than diesel [29]. The emission of carbon monoxide, hydrocarbon, oxides of nitrogen and smoke were decreased by 58, 63, 12 and 70 per cent, respectively, in comparison with diesel.

ACKNOWLEDGMENT We express our personal appreciation for valuable suggestion and comments given by Prof. B. L. Salvi on this chapter. Without their co-opration, the extensive work involved in compling background information for biofuel scenario in Indian context and preparing the chapter for publication would not be possible.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

REFERENCES [108] Conceicao, M.M.; Roberlucia, A.; Candeia, R.A.; Hermesson, J.; Dantas, H.J.; Soledade, L.E.B.; Fernandes, V.J.; Souza, A.G. Rheological Behavior of Castor Oil Biodiesel. Energy and Fuels.2005,19, 2185-2188. [109] UNDP (United Nations Development Programme). Energy and the challange of sustainability. World energy assessment, 2000. [110] IEA (International Energy Agency). 2004. Biofuels For Transport: An International Perspective. 9, rue de la Fédération, 75739 Paris, cedex 15, France. http://www.iea.org. [111] Hansen, A. C.; Zhang, Q.; Lyne, P. W. L. Ethanol-diesel fuel blends-a review. Bioresource Technology 2005,96,277-285. [112] Raghuraman, V.; Ghosh, S. A report on Indo-U.S. Cooperation in Energy – IndianPerspective.www.acus.org/docs/0303-IndoU.S._Cooperation_Energy_ Indian_Perspectives.pdf 2003 (Assess on April 2, 2008) [113] Malhotra, R. K. and Tikku, P. How is India changing the global perspective presented on Clean Vehicles and Fuels Symposium, Stockholm, 9-10 November 2005, http://www.managenergy.net/conference/0511cvf/tikku.pdf. [114] Demirbas, A. Biodiesel from vegetable oils via transesterification in supercritical methanol. Energy Convers Manage 2002,43, 2349-2356. [115] Shrirame, H.Y.; Panwar, N.L.; Bamniya, B.R. bio diesel from castor oil – a green energy option. Low carbon economy. 2011,2(1),1-6. [116] Ghadge, S. V.; Raheman, H. Process optimization for biodiesel production from mahua (Madhuca indica) oil using response surface methodology. Biores. Technol. 2006,97,379-384. [117] Panwar, N.L.; Shrirame, H.Y. The emission characteristics of a compression ignition engine operating on castor oil methyl ester. International Journal of Global Warming. 2009,1(1-3),368-377 [118] Kusdiana, D.; ; Saka, S. Kinetics of transesterification in rapeseed oil to biodiesel fuels as treated in supercritical methanol. Fuel 2001, 80:693-708. [119] Ma F.;Hanna M. A. Biodiesel production: a review. Bioresource Technology. 199,70,115.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

194

Hemant Y. Shrirame and N. L.Panwar

[120] Goodrum, J. W. 2002. Volatility and boiling points of biodiesel from vegetable oils and tallow. Biomass and Bioenergy. 2001, 22:205-211. [121] Saucedo, E. Biodiesel. Ing. Quim.2001,20,19-29. [122] Altin, R.; Cetinkaya, S.; Yucesu, H. S. The potential of using vegetable oil fuels as fuel for diesel engines. Energy Convers. Manage.2001, 42,529-538. [123] Giannelos, P.N.; Zannikos, F.; Stournas, S.; Lois, E.; Anastopoulos, G. Tobacco seed oil as an alternative diesel fuel: physical and chemical properties. Ind .Crop. Prod. 2002,16,1-9. [124] Panwar, N.L.; Shrirame, H.Y.;. Bamniya.B.R. CO2 mitigation potential from biodiesel of castor seed oil in Indian context. Clean Techn. Environ. Policy. 2010,12,579–582. [125] Janaun, J; N. Ellis,N. Perspectives on biodiesel as a sustainable fuel. Renewable and Sustainable Energy Reviews. 2010,14,1312–1320. [126] M. Lapuerta, M.; Armas,O.; Fernandez.J.R. Effect of biodiesel fuels on diesel engine emissions. Progress in Energy and Combustion Science. 2008, 34,198–223. [127] Gui, M.M.; Lee,K.T.; Bhatia, S. ―Feasibility of edible oil vs. non-edible oil vs. waste edible oil as biodiesel feedstock‖, Energy.2008,33(11),1646–1653. [128] Jaecker-Voirol,A.; Durand, I.; Hillion,G.; Delfort,B.; Montagne,X. Glycerin for new biodiesel formulation., Oil Gas Sci. Tech. 2008,63(4),395–404. [129] Castor seed Seasonal Report (2008) Karvys special reports 20080424-02. www.karvycomtrade.com Accessed 20 Mar 2009. [130] Castor outlook (2005) Karvys special reports 20051119-01. www.karvycomtrade.com. Accessed 20 Mar 2009. [131] FAOSTAT 2005. http://faostat.fao.org. [132] Statisatical Abstract http://www.ikisan.com/links/ap_castorHistory.shtml access on 6/5/2008). [133] http://www.castrol oil.htm. [134] Conceicao, M.M.; Candeia, R.A.; Silva, F.C.; Bezerra, A. F.;Souza, A.G.. Thermoanalytical characterization of castor oil biodiesel. Renewable and Sustainable Energy Reviews 2007,11, 964-75. [135] BioFuel Technology Handbook-by Dominik Rutz, Rainer Janssen WIP Renewable Energies- 2007) [136] Puhan, S.; Vedaraman, N.; Sankaranarayanan, G.; Bharat Ram, B.V. Performance and emission study of Mahua oil (madhuca indica oil) ethyl ester in 4-stroke natural aspiration direct injection diesel engine. Renewable Energy. 2005, 30, 1269–1278. [137] Lapuerta, M.; Armas, O.; Fernandez, R.J. Effect of biodiesel fuel on diesel engine emission. Progress in Energy and Combustion Science.,2008,34,198–223. [138] Ramadhas, A.S.; Muraleedharan, C.; Jayaraj, S. Performance and emission evaluation of a diesel engine fuelled with methyl esters of rubber seed oil. Renewable Energy. 2005, 31,1789–1800. [139] Chhina, R.; Verma, S.R.; Sharda, A. Exhaust emission characteristics of an un-modified diesel engine operated on bio-diesel fuels. Journal of Agricultural Engineering. 2005, 42,38–43.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

In: Liquid Fuels: Types, Properties and Production Editor: Domenic A. Carasillo

ISBN 978-1-61470-435-5 © 2012 Nova Science Publishers, Inc.

Chapter 6

CHARACTERIZATION OF MULTIFUEL ECO-BLEND (DIESEL–BIODIESEL–BIOETHANOL) FOR UNMODIFIED CI ENGINES 1

Laurencas Raslavičius1 and Žilvinas Bazaras2

Department of Transport Engineering, Kaunas University of Technology Kaunas, Lithuania 2 Department of Mechanical Technology, Kaunas University of Technology Panevėžys Institute, Panevėžys, Lithuania

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

NOMENCLATURE A* c

liq p

Е L R r r1 T0 T1 Т Tb

dimensionless coefficient specific heat capacity of liquid fuel (J kg-1 K-1) activation energy (J mol-1) latent heat of vaporization (J mol-1) universal gas constant (J mol-1 K-1) initial drop radius (m) distance to the zone, where chemical reaction begins (m) droplet temperature at initial time moment (K) temperature of the drop surface at the moment of ignition (K) ambient temperature (K) boiling temperature (K)

Greek Symbols 0

λgas ρ

temperature tensions between droplet surface and environment (K) thermal conductivity of fuel–vapour (W m-1 K-1) density (kg m-3)

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

196

Laurencas Raslavičius and Žilvinas Bazaras τign τcomb τtotal φ

ignition delay time (s) time of combustion (s) time of drop burnout (s) stoichiometric coefficient

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

1. INTRODUCTION Great demands are being placed on energy production, especially with regard to environmental impact. Restrictions have been set on sulfur and nitrogen emissions from diesel engines and the Kyoto International Climate Convention limits carbon dioxide emissions. While implementing the commitments regarding climate change and the use of renewable resources as a fuel in the EU-27 states, one of the main energy policy goals of the European Community is taken into account – promotion of the appliance of biofuels by changing the fuel distilled from oil and used for transport. EU summit sets target of 10% of transport fuel in each member state to be provided by biofuels by 2020. Adaptation actions have to complement reduction actions regarding climate change and dependency on oil products inevitably. Currently, various standards and specifications set rather tight limits to the composition and properties of motor fuels. Some blends have already received approvals for special applications. A number of different oxygenates have been considered as components of diesel fuel (DF). These oxygenates include various alcohols, ethers, esters and carbonates [1, 2]. Discussing the oxygenated fuels, biodiesel is the most common one and almost all practical experiences have been generated from the use of DF/biodiesel blends. The combustion properties of biodiesel, in particular rapeseed oil methyl ester (RME) are somewhat similar to DF. Much of the world uses a system known as the ―B‖ factor to state the amount of biodiesel in any fuel mix: fuel containing 20% biodiesel is labeled B20, while pure biodiesel is referred to as B100. Attempts have been made by various researchers to determine the best composition of biodiesel blend [3, 4]. Studies on biodiesel blends conducted by Schumacher et al. [5], Sinha and Agarwal [6], and Bora et al. [7] indicate that a B20 blend might represent the performance and emission advantage. Others state [8] that concentration of biodiesel fuel up to and equal to 30% in mixture with DF is optimal to be used practically in respect of fuel saving change and effect of the improvement of ecological parameters. Notwithstanding, in many EC countries, the previously applicable standards for biodiesel fuel have declared a total share for fatty acid methyl ester (FAME) as 30% to compound DF, later have been revoked (for example LST 1708:2001) [9]. Though, neat biodiesel (RME) or its higher volume blends with diesel fuel (B30, B50), however, as often as not pose various long-term problems in out-of-date unmodified compression ignition (CI) engines, e.g., ring-sticking, injector coking, injector deposits, etc. These undesirable features of biodiesel blends are because of their inherent properties like high viscosity, polyunsaturated character, and presence of the contaminants of free and total glycerol, especially [10]. A problem of glycerol is distinctive for the large-scaled farms disposing inconsiderable capacity equipment and producing biodiesel for own purposes of a quality often cannot compete to the sold in the network of realization [9]. Combining of the several types of biofuel could be an easiest possible solution to correct key physical–chemical properties of the fuel blend. Application of

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Characterization of Multifuel Eco-Blend (Diesel–Biodiesel–Bioethanol) …

197

the small quantities (v/v/) of bioethanol is among the multi–choice options. One of the main advantages in application of the multifuel eco-blend (diesel–biodiesel–bioethanol) in CI engines is that total glycerol content situated in the formation of RME follows to be melted (thus prolonging transesterification step for biodiesel) by the bioethanol within the DF/RME blend. Another fact at issue for FAME is an overly increased Cetane number (CN) [11, 12]. It measures the readiness of the fuel to auto–ignite when injected into the engine. Ignition quality is one of the properties of biodiesel that is determined by the structure of the fatty acid methyl esters (FAME) components [2]. The current standard for Diesel sold in European Union, Iceland, Norway and Switzerland is set in EN 590, with a minimum Cetane index of 46 and a minimum Cetane number of 51. The CN of rapeseed methyl ester is generally observed to be quite high. Data presented below will show values varying between 53 and 65 (Table 1). Table 1. Reported values of Cetane number for RME

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

No 1. 2. 3. 4. 5. 6. 7.

Cetane number 53.0 54.4 54.5 59.0 61.2 61.8 65.0

Source [14] Rakopoulos et al., 2006 [15] Feldman and Peterson, 1993 [16] Reece and Peterson, 1993 [17] Takesawa, 1993 [18] Peterson et al., 1994 [19] Peterson and Reece, 1994 [20] Vellguth, 1983

Drastic increase in Cetane number over values actually required (Table 1, positions 4–7) does not materially improve engine performance [21]. Many authors admit that only slightly increased CN signifies short delays between fuel injection and ignition [11–13], and thus ensures good cold start behavior and smooth run of the engine [13]. It is known from experience that CN requirements depend on engine design, size, nature of speed and load variations, and on starting and atmospheric conditions [13]. These engine fuel requirements are published in the operating manual for each specific engine or vehicle. Accordingly, the CN specified should be as low as possible to ensure maximum fuel availability. Mentioned quote underscores the importance of matching engine CN requirements with fuel Cetane number [9, 13]. This means that problems occur of further increasing the quantity of biodiesel (in peculiar RME) in blends with fossil diesel without serious modifications of the engine‘s operating parameters [22, 23]. Citing Kwanchareon et al. [12], the high CN value of biodiesel could be compensate for the decreased Cetane caused by the presence of bioethanol in diesel fuel. This mean that optimum adequacy to the conventional fuels must be secured for newly derived bio-based substitutes to warrant the efficient performance of fuel-handling equipment. On this understanding, development in fuel formulation indicates that multi–component effects will become progressively more important in the utilization of liquid biofuels [24, 25]. Appealing to facts established by Janulis et al. [26] and Kwanchareon et al. [12], the settlement of bioethanol additives to correct certain key properties and maintain blend stability is suggested as a critical factor in ensuring DF–RME compatibility with engines. Citing Szklo and

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

198

Laurencas Raslavičius and Žilvinas Bazaras

Schaeffer [27], energy carriers for multi–fuel and multi–product strategies, allied to other co– benefits, especially those related to the increased use of renewable energy sources. However, the cause and effect relationships implicit in the test results are often hard to interpret, thus making it difficult to establish strategies that carry–over from one design iteration to the next through experimentation alone. On the other hand, modeling approaches, although less precise in predicting the outcome of a specific test, can effectively isolate one variable at a time and point out trends and causes. In pursuance to increase the utilization rates of the standardized biofuels simultaneously holding a significant impact on the improved exploitation characteristics of CI engine led to a large-scale research activity, which objective was to develop a mathematical expression for establishment of ignition delay characteristics for different multifuel blend ratios as well as verify energy and emission characteristics of the diesel–biodiesel–bioethanol blends under the laboratory conditions and in practice. Following tasks demanded to work objective realizing were provided: 

 

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.



Modification of the mathematical theory of combustion based quasi–stationary fuel drop combustion model (hereinafter Q–S model) tailoring it as easy to be used for ignition delay calculations of the multi–component fuel blends. Establishment of energy and emission characteristics of the 37 kW capacity diesel engine at variable load and constant torque rotational speed. Establishment of the energy and emission characteristics of the 18 kW tractor unit operating on diesel–biodiesel– bioethanol fuel under on–field conditions at variable load and torque rotational speed. Substantiation of the optimum composition of multifuel blend, closest to fossil diesel according to its operational characteristics on the basis of mathematical modelling and experimental trial results.

Complex experiments (Q–S modelling, drop combustion experiments, diesel engine brake–stand tests, and on–field test trials) were carried out using blends composed of DF, RME and bioethanol. Results showed that good levels of agreement between experiments and predictions were obtained.

2. MATERIALS AND METHODS 2.1. Tested Fuels Three types of fuel i.e. diesel fuel, rapeseed methyl ester and bioethanol (Table 2) were compounded in various proportions (v/v) and tested by Q–S model, drop combustion laboratory device, engine brake–stand, and tractor T25A of 18 kW capacity (see Table 3). A pruned nomenclature of fuel blends B100, B50 and B30 means what percentage of biodiesel is actually in the fuel, the rest is fossil diesel. Hereinafter applied abbreviations ―+2.5E‖, ―+5E‖, ―+7.5E‖ and ―+10E‖ given to describe bioethanol compounding volume to B30 and B50 blends, respectively 2.5%, 5%, 7.5% and 10%.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Characterization of Multifuel Eco-Blend (Diesel–Biodiesel–Bioethanol) …

199

Sulfur content, mg kg-1

Water content, mg kg-1

Ash content, % of mass

Total glycerol, % of mass

830

4.00

55

–

51

350

200

0.01

–

884.3

4.7

150

96.5

56

3

223

0.007

0.51

791

1.07

21

99.66

8

2.54

0.34

–

–

Flash point, 0C

Cetane number

Diesel fuel (DF) LST EN 590:2004 [28] Biodiesel fuel (B100) LST EN 14214:2009 [29] Bioethanol (E) LST EN 15376 [30]

Viscosity at 40oC, mm2 s-1

Fuel / Abbreviation / Standard

Density at 15oC, kg m-3

Parameter

Absolute content, % of mass

Table 2. European standard requirements for the tested motor fuels

Table 3. Types of fuel related to expedient test method Fuel DF

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

DF+5E DF+10E

B30 B30+2.5E B30+5E B30+7.5E B30+10E B50 B50+5E B50+10E B100

Test method Q–S model / Drop combustion stand / Brake-stand / On-field On-field On-field Q–S model / Drop combustion stand / Brake-stand / On-field Brake-stand Q–S model / Drop combustion stand / Brake-stand / On-field Brake-stand Q–S model / Drop combustion stand / Brake-stand / On-field On-field On-field On-field Q–S model / Drop combustion stand

2.2. Preparation of the Fuel Blends The compounds of biodiesel blends provided for drop combustion laboratory experiments were prepared by applying the Blaubrand 5.0–ml graduated pipettes (ISO 835, subdivision 0.05 ml, error limit 0.030 ml, Class AS). A size of bioethanol additives to admix the prepared blends controlled via Blaubrand 0.5–ml pipette (ISO 835, subdivision 0.01 ml, error limit 0.006 ml, Class AS). Compounding of biodiesel blends (B30, B50), intended for engine brake–stand trial procedure and on-field tests prepared by using Pyrex 500–ml graduated glass cylinder with spout (ISO 4788, subdivision 5.0 ml, error limit 2.5 ml Class A). A dosage outfit Simax 100–ml burette with straight glass one–channel stopcock (ISO 835, subdivision 0.2 ml, error limit 0.1 ml, Class A) applied to take the advanced measures of bioethanol. All blends were prepared by a splash mixing technique.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

200

Laurencas Raslavičius and Žilvinas Bazaras

2.3. Drop Combustion Laboratory Test

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Suspended single droplet experiments were performed to obtain the fuel ignition characteristics prepared at different furnace temperatures and compare them to the Q–S model data. Electric furnace mounted on an elevating support stand of the design shown schematically in Figure 1a. Overall heating unit‘s dimensions are 0.700 m diameter by 0.120 m in length. The position of the furnace may be manually adjusted through a horizontal displacement rails. The drops of the radius 10.05 mm were mounted to a calibrated type S thermocouple at room temperature using a glass syringe. An optical system using a light flow was developed and employed to control drop size. The system uses special binoculars and graduated screen where droplet reflection is visible. As soon as a drop was into the electric furnace, the stop watch was automatically switched on. A distance between drop and thermocouple measuring ambient temperature was controlled by the synchronizing contacts.

Figure 1. Drop combustion stand: a – common view; b – circuit diagram.

If too many experiments were carried out, the vapor pressure of the fuel in the furnace increased and had an effect on the combustion. In order to avoid this effect, the air in the furnace was properly changed after every second experiment. Depending on tested fuel surface tension characteristics the most suitable temperature ranges for both, diesel fuel and RME drops of the radius 1 mm were 900–1000 K.

2.4. Brake–Stand Tests Tests have been conducted using an electromechanical system composed of a 4.2 l T40M tractor diesel engine D–144 with mechanical power of 37 kW at 1600 rpm coupled with an asynchronous generator AKB–82–4UZ of 55 kW (Figure 2). Specifications for the natural aspirated, direct injection, four–cylinder engine are as follows: bore/stroke – 110/120 mm; compression ratio 16.5; piston bowl shape – dished piston; No. of fuel injector holes – 3; initial fuel delivery starting – 25±10 before top dead center; needle valve lifting pressure for all injectors 17.5 ± 0.5 MPa (Figure 2).

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Characterization of Multifuel Eco-Blend (Diesel–Biodiesel–Bioethanol) …

201

Figure 2. Brake–stand scheme.

Emission of exhaust gases measured via the gas analysers Technotest 481 and Bacharah PCA–65 as well as smoke–meter Technotest 490 (Table 4). Before carrying out stand experiments Technotest equipment was calibrated at Vilnius Metrology Centre (LT). Table 4. Exhaust gas measuring equipment Parameter Principle

Technotest 490 Optical density

PM

0 – 100 (); accuracy: 0.2 ()

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

CO

0 – 9.99 (); accuracy: 0.01 () 0 – 1995 (ppm); accuracy: 2 ()

HC NOx Max. engine speed Ambient temperature Max. gas temperature Nominal gas flow rate Allowable gas flow rate Warm–up time Calibration method

Technotest 481 Infrared absorption spectroscopy

0 – 5100 (rpm) 5 – 40 (0C) – 8 (l min-1) 5.0 – 12.0 (l min-1) 15 (min) EN 61000-6-4

EN 61000-6-4

Bacharah PCA–65 Infrared absorption spectroscopy

0 – 1000 (ppm); accuracy: 2 () – 0 – 40, (0C) 800 (0C) – – 60 (s) EN 61000-6-4

The fuel was delivered by single–plunger fuel pump (ND 21/4) through three holes injection nozzles with the initial fuel delivery starting at 25±10 before top dead center (BTDC). The needle valve lifting pressure for all injectors was set to 17.5 ± 0.5 MPa. Before starting the brake–stand tests, engine crankcase was fulfilled with 11 l of motor oil M-10G2K according the exploitation manual requirements. High speed diesel engine torque measured via dynamometer with ±2% accuracy. The revolution frequency of the crankshaft was measured with digital tachometer Tessa–1 that guarantees an accuracy of ±1%. Fuel supply and pour–out pipes were braced on the special support–console safeguarding any possible contact with the walls of glass conical flask thus ensuring correct data showings of electronic

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

202

Laurencas Raslavičius and Žilvinas Bazaras

weighting machine IPC–WP (water–proof scale; accuracy: ±0.5 g). The duration of the every single test was controlled with the help of second–meter SDS (accuracy: ±0.2 s). The accomplishment of the brake–stand tests was launched by running of the engine at fast idling speed until it attains a normal operating temperature indispensable for establishment of load and blend composition characteristics. After achieving the establishment of operating mode we schedule to run engine for 5–10 min. making an appeal to the test accuracy. The engine load characteristics were taken with a gradual increase from the point that was close to zero up to its maximum value (n=const=1600 min-1). Loading range was divided up to 6 equal graduations (6 kW, 12 kW, 18 kW, 24 kW, 30 kW, and 36 kW) later converted to the brake mean effective pressure (bmep, MPa). For the every engine load fuel consumption test was accomplished by measuring a time of 200 g fuel burn out. Mainly, at the given loading conditions, comparative analysis of the engine performance on the various oxygenated multifuel bends as well as emission characteristics were performed while repeating every measuring procedure for 5 times. After completing a trial with particular type of investigated fuel, engine continues running for 5–10 min. at no load mode before shutdown. The residues of the used fuel needs to be ejected out of the supply system and filters as well as fine filter element been replaced. Then, a fulfilling of the supply system with the next in the row type of fuel and removing of the participating air with the help of manually operating pump keeps the track of events. Whereupon, engine start–up and running at no load mode for 10–15 min. to burn out fuel residues leftover the high–pressure pump, pipes and injectors follows the repeating aforementioned procedures.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

2.5. On–Field Test Trials On–farm tests were performed with tractor T25A of 18 kW capacity (Figure 3). Specification for T25A is summarized in Table 5.

Figure 3. Scheme of equipment used for tractor unit‘s fuel consumption and exhaust emission measuring: 1 – tensometric wheel rod; 2 – wheel rotation, skid and traction sensors; 3 – electronic integrator EMA-PM; 4 – fuel consumption meter; 5 – time meter; 6 – tractor‘s diesel engine; 7 – fuel reflux pipe; 8 – high pressure fuel pump; 9 – fuel supply valve; 10 – gas analyzer PCA–65; 11 – gas analyzer Technotest–481; 12 – smoke-meter Technotest–490; 13 – reserved power supply unit; 14 – temperature meter; 15 – electronic weighing–machine IPC–WP; 16 – pipe for feeding fuel to pump.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Characterization of Multifuel Eco-Blend (Diesel–Biodiesel–Bioethanol) …

203

Tractor unit‘s traction force resistance Rm was identified using tensometric equipment: 1.5–3.0 t traction catenary and EMA–PM register. Hourly fuel consumption measured via volumetric gauge, integrated into diesel engine high pressure fuel pump supply system. Fuel consumption identified measuring a weight of volume with fuel before and after experiment with the help of electronic waterproof scale IPC–WP (class IP65, error ±0.5 g). Research with the same type of fuel and engine load was repeated for 8 times. Experiment performed in four different working speeds (four gears) at 1.5–2.7 m/s. Comparative fuel consumption identified at variable engine loads. Tractor unit operating speed and slip of the driving wheels was fixed with the help of wheel rotation sensors across the length of field, the total distance 500 m. Table 5. Tractor technical parameters

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Technical parameters Manufacturer Engine Engine size, cm3 Nominal power, kW Number of cylinders Cylinders operating order Cylinder diameter, mm Stroke, mm Compression ratio Cooling system Chassis drive arrangement Gears Fuel Mass, kg

Tractor Wladimirec (RUS), modification – T25A D21A1, two–cycle, direct injection 4100 18 2 1–2–0–0 105 120 16.5 Air–cooling rear–wheel drive (RWD) forward 8, backwards 6 Diesel fuel (EN 590) 1780

3. THEORY OF MULTIFUEL DROP IGNITION A drop of liquid fuel with radius r0=1mm placed in heated stationary oxidising environment with its gas temperature Т was analysed (Figure 4).

Figure 4. Simplified scheme of fuel drop ignition [23, 30]: 1 – droplet surface; 2 – fuel vapour; 3 – heat; 4 – oxidizer; 5 – zone where chemical reaction starts (separating fuel vapour from oxidizer); 6 – reaction products Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

204

Laurencas Raslavičius and Žilvinas Bazaras

In 1966, Varshavsky et al., [32] derived an expression accepted as a basis to describe fuel drop burning process using a quasi-steady model, which is considered to be a milestone in combustion theory. In this model the flame zone, as a consequence of the infinite rate assumption, is of infinitesimal thickness and would thus be represented by a surface rather than an extended reaction zone. Generally it is necessary to assure that the fuel and oxidant diffuse to the reaction zone in stoichiometric proportions and again, as a consequence of the infinite reaction rate assumption, their concentrations become zero at the reaction interface. When these approximations are made an analytic solution may be obtained. The forms of the final equations depend upon the exact method of solution. Thus Varshavsky et al., [32] have developed an equation in which:  3   gas   ign   T0  1   exp     liq 2    c p  r0  r1  T    r0   8  R  T E 1  1  1 4  R  T  E 

(1)

Based on further re-arrangements ignition delay time τign depended upon both: the distance from the ignition point (r1/r0) as well as temperature of the drop surface at the moment of ignition T1:

 3   gas   ign   ρ  c liq  r 2  p 0  

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

T1  T  T  T0   exp  

(2)

Therefore, seizing Varshavsky et al. [32] based Q–S ignition theory we‘ve derived a basic expression for the calculations of ignition delay of hydrocarbon fuels: 

 ign 

 T0 R  Tb   E   0 1  ln L R  T 1  T 1      0  1  R  Tb ln   E   0   L R  T  

liq 2 ρ  c p  r0 

3

gas

R  Tb

Admitting that

 ign 

ln

L

 c r liq p

3

gas

2 0

  E  0 R  T

 1

(3)

, expression (3) can be written as:

 Tb  T0     T  T0  , or



     

  c p  r0 liq

ign



3

gas

2

T0   1 T  ln   1  Tb  A*  T  

     

Here:

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

(4)

Characterization of Multifuel Eco-Blend (Diesel–Biodiesel–Bioethanol) …

205

  T  1 0  R  Tb  T   * A  1 ln    T  r1   1     L  1    T   

It was established by calculations that A* depended little on temperature and in the case of octane droplet ignition its value was close to one.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Figure 5. Dependence of the dimensionless coefficient А* on ambient temperature for octane drop of radius 1 mm.

Having evaluated this we can put the final expression of equation to calculate ignition delay time as follows:

  c p  r0 liq

τ ign 

3 

gas

2

 T  T0  .  T  Tb 

ln 

(5)

To test the accuracy of this formula the calculations of octane as one of the best investigated hydrocarbons were made (Figure 6). It has been shown many times experimentally that under burning conditions the square of the drop diameter is a function of the time of combustion [22, 34–37]. According to equation (5), ignition delay is directly proportional to initial drop radius. As illustrated in Figure 6a, drops of the bigger diameter related to higher values of ignition delay time. Both curves describing the dependence of ignition delay on ambient temperature are of the similar character as well (Figure 6b). However, a newly deduced formula is in average 8–10% less precise compared with equation (1) but being much simpler than the complicated expression (3).

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

206

Laurencas Raslavičius and Žilvinas Bazaras

Figure 6. Q–S model validation results [33]: a – dependence of the ignition delay time on initial drop radius of the octane fuel; b – dependence of the ignition delay time of the octane drop of r01 mm on ambient temperature (calculated by Eqs. (1) and (5)).

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

A new simplified approximate mechanism of combustion of the multifuel drop has been validated against several independent data sets. The new mechanism is simple enough to be used for computational studies of multi–component droplets. Using a standard methodology and settled findings of different researchers, physical–chemical characteristics of the fossil diesel [25, 37–42], RME [25, 39, 43–46] and bioethanol [25, 39, 45, 47, 48] as well as their generic compounds (v/v) [22–24, 33, 36, 37, 39] were obtained (Table 6). Table 6. Physical–chemical characteristics (at T293 K) of the fuels for Q–S application approach Fuel DF B100 E B30 B30+5E B30+10E

, kg m-3 860.0 900.0 791.0 872.0 868.1 864.6

liq

cp

,

J kg-1 K-1 1800.3 1670.0 2439.8 1761.2 1793.5 1822.9

gas x10-4,

T0,

Tb,

W m-1 K-1 95.72 66.28 148.6 85.56 87.40 89.12

K 739.4 755.0 514.0 744.1 733.1 723.2

K 553.0 610.0 351.5 557.4 547.2 537.9

Simulation results while applying the Q–S model showed, that admix of 30% by volume of RME to pure diesel causes the decrease in ignition delay (see Figure 7), and bioethanol – on the contrary, helps to heighten duration of τign for B30 blend. We can see from Eq. (5) that the increase of τign was determined by the decreased boiling temperature due to bioethanol additive and increased specific heat capacity of the blend. These values determine increased vaporization rates and vapour–diffusion, therefore, the ignition delay of combustible mixtures (B30+5E and B30+10E) is increased. During mathematical modelling it was established that the ignition delay time closest to fossil diesel was achieved by the blend B30+5E.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Characterization of Multifuel Eco-Blend (Diesel–Biodiesel–Bioethanol) …

207

Figure 7. Ignition delay simulation using a Q–S model.

4. RESULTS 4.1. Combustion of the Single Drop of Oxygenated Fuels

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

A single fuel drop set at the tip of calibrated thermo–couple was inserted into an electric furnace and ignited. The difference between the conditions in the furnace and those in the combustion chamber of diesel engines is that the air inside the furnace is not compressed (to about 30 x 105 Pa) and there is no stream caused by compression stroke [49]. However, characteristics of the combustion of oxygenated fuel blends can be compared with fossil diesel in the same condition [9, 21–23, 31, 32, 34, 37, 43, 49]. Table 7. Life histories of the drops of oxygenated fuel blends [9] T , K 900 910 920 930 940 950 960 970 980 990 1000 1010

DF

ign,

s – – – 4.21 3.90 3.71 3.58 3.51 3.10 3.00 2.71 2.62

B100

comb, s – – – 0.38 0.35 0.41 0.50 0.52 0.74 0.69 0.75 0.82

total, s – – – 4.59 4.25 4.12 4.08 4.03 3.84 3.69 3.46 3.44

ign,

s 4.46 4.02 3.70 3.52 3.21 3.00 2.71 2.50 2.15 1.83 1.59 1.60

B30

comb, s 1.66 1.58 1.45 1.39 1.35 1.41 1.66 1.81 1.96 2.12 2.13 2.10

total, s 6.12 5.60 5.15 4.91 4.56 4.41 4.37 4.31 4.11 3.95 3.72 3.70

ign,

s – – 3.94 3.71 3.50 3.27 2.95 2.68 2.45 2.21 2.11 2.00

B30+5E

comb, s – – 0.88 0.95 0.97 0.95 1.25 1.49 1.56 1.61 1.48 1.58

total, s – – 4.82 4.66 4.47 4.22 4.20 4.17 4.01 3.82 3.59 3.58

ign,

s – – 4.34 3.99 3.79 3.51 3.42 3.26 2.98 2.85 2.58 2.49

comb, s – – 0.28 0.29 0.52 0.66 0.71 0.82 1.92 0.89 0.92 0.98

B30+10E

total, s – – 4.62 4.28 4.31 4.17 4.13 4.08 3.90 3.74 3.50 3.47

ign,

s – – – 4.50 4.18 4.00 3.87 3.79 3.40 3.31 3.03 2.94

comb, s – – – 0.33 0.37 0.39 0.44 0.48 0.71 0.72 0.77 0.79

total, s – – – 4.83 4.55 4.39 4.31 4.27 4.11 4.03 3.80 3.73

The ignition delay measured as a function of fuel composition, and ambient temperature. A drop radius (1 mm) was constant for all sets of experiment. We define the period of time from the point of insertion of the drop into the furnace until ignition occurs as "ignition delay (ign)" [9, 43]. A stop–watch sensed a time of drop combustion (comb) as well. A sum of the ignition delay time and time of drop combustion entitled as a time of total burnout of fuel

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

208

Laurencas Raslavičius and Žilvinas Bazaras

drop (τtotal). Altogether, those three parameters present a clear view of drop life history (Table 7). An exact size for all drops was selected experimentally: when the drop size was less than 1 mm, the drop did not ignite but only evaporated. In other words, the ignition delay in this case became infinite [9]. This may be due to the fact that the mixture of the fuel is too lean to ignite (beyond the inflammation limit) when single drops of volatile fuels are inserted. Bigger drops of the radius above 1 mm fell dawn from the tip of thermo–couple. This observation is explained by decrease in drop‘s surface tensions after compounding of RME and bioethanol to diesel fuel [22].

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Figure 8. The dependence of the ignition delay on ambient temperature and fuel composition (drop radius r0=1 mm; P=1 atm) [9].

As seen in Figure 8, the ignition delay of rapeseed methyl ester (B100) is shorter than that of any other fuels tested. A newsworthy data was obtained while studying a life history of pure biodiesel: as it happens, a time of drop combustion seems to be significantly prolonged when comparing it with those of the fossil diesel. The fuel ignition delay was lowered as a result of smaller bioethanol addition. The improvement in ignition delay of the B30+5E seems to lead to the evident improvement of the time of combustion as well. The ignition delay of B30+10E drop was longer than of DF ones. This means, that a prolonged life of the B30+10E drop can be a critical moment when discussing about increased rates of fuel consumption as well as emission of exhaust gases. In summary, the theoretical values are a little bit smaller than the experimental data but both of them have the same tendency and are in strong agreement.

4.2. Brake–Stand Test Results Diesel–based advanced combustion regimes are combustion regimes that result in much lower NOX and PM emissions as well as fuel consumption rates than traditional combustion processes. Formation of a fuel–lean, pre–mixed region inside the fuel jet may be influenced by several fuel properties, including the oxygen content, viscosity, and boiling range. Initiation of combustion inside such a region may also be influenced by fuel properties such as the Cetane rating. Hence, there may be opportunities for tailoring the fuel properties in a

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Characterization of Multifuel Eco-Blend (Diesel–Biodiesel–Bioethanol) …

209

way that results in increasing the operating envelope where advanced combustion can be utilized reliably. This may be realized either through fuel reformulation or through the use of the additives of biological origin. Measurement points were chosen in such a way, that the comparison of diesel engine exploitation parameters could be obtained for the same load but for different ratio of bioethanol to B30. Three basic loads true to the type of the heavy duty transport means of agricultural purpose were selected to discuss the results of brake–stand test: low (0.100 MPa), average (0.325 MPa) and high (0.650 MPa). The improved Cetane number of the B30+5E and B30+7.5E compounds causes the multi–component blends to perform well despite appreciating to increased volume of bio– based fuels. In the all ranges of engine load, the admix of bioethanol of the total volume 7.5%, leads to the achieving of BSFC rates in close proximity to the ones of fossil diesel (see Figure 9a). Nonetheless substantial differences in fuel consumption were observed between the test fuels as engine load was varied. However, after the sharing of 10% (v/v) bioethanol additive in the blend, a negative effect has been achieved. A fair increase of the BSFC of B30+10%E blend has been observed due to the significant decrease of the heating value and viscosity of the fuel. This fact leads to the conclusion, that sharing of the bioethanol additives exceeding 7.5 % (v/v) to B30 is not recommendable if no changes in engine operational parameters were adjusted. The bio–based combustible mixtures fuelled engines distinguish for their increased nitrogen oxides emissions (see Figure 9b). Under the test conditions reported herein, we have demonstrated that B30+5E and B30+7E blends have lower NOX emissions than pure B30 blend. Additionally, for the test engine used in this study, the small doses of bioethanol did not increase NOX emission levels above those measured for fossil Diesel. This indicated that under the conditions used here, the three–component biodiesel was NOX neutral. This NOX decrease is significant because it eliminates the increase in NOX emissions observed when a 30% blend of rapeseed methyl ester is substituted to pure Diesel. This suggests that by judiciously blending biofuels from different feedstock, a NOX –neutral biodiesel fuel can be obtained. When analyzing the level of particulate matter (PM) emission, in the function of brake mean effective pressure produced (Figure 10a), one can observe a significant decrease of PM quantity along with the increase of engine load. It was proved by the experiments that after compounding of B30 blend with 7.5% of bioethanol, solid particle emission decreased: at low and average engine loads by 11 and at high load mode – 13. Similar results were ascertained while fuelling diesel engine on B30+5E. Most of carbon monoxide (CO) emissions from automotive CI engines are produced during the engine warm–up period and are primarily caused by difficulties in obtaining stable and efficient combustion under these conditions. This problem is more pronounced in diesel engines where the temperatures of the exhaust gases are lower. In fact, operating temperature can be reached after the first ten minutes of engine operation and after that, oxidation of the exhaust gases proceeds efficiently. Instantaneous CO measurements are shown in Figure 10b. Carbon monoxide gas is a toxic byproduct of all hydrocarbon combustion that is also reduced by increasing the oxygen content of the fuel. More complete oxidation of the fuel results in more complete combustion to carbon dioxide rather than leading to the formation of carbon monoxide. It is possible to observe the differences in the levels of emission of carbon monoxide between two engine characteristics: at the speed of the maximum torque (1600

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

210

Laurencas Raslavičius and Žilvinas Bazaras

min-1), as well as low and average loads. These differences fall within the range from 30% to 35% and are the least significant for the B30 fuel having 7.5% of bioethanol.

Figure 9. Comparison of the diesel–biodiesel– bioethanol blends: a – BSFC rates (bioethanol-blended B30 vs. pure DF); b – dependence of the NOX emission level on the volume of bioethanol admixed to B30 [9].

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

In general, using of admixes of bio–based additives to compound fossil diesel, irrespective to their origin and the discussed above necessity to combine them in relative proportions, allows to decrease in emission levels of carbon monoxide dramatically. Moreover, the emission of CO diminishes when operating diesel engine of the heavy duty transport mean at overloaded mode conditions.

Figure 10. Dependence of the emission level on the volume of bioethanol admixed to B30: a –PM; b – CO [9].

4.3. On–Field Test Results Established specific fuel consumption (SFC) rates of the tractor T25A (18 kW capacity) working at maximum traction force and nominal engine revolution speed under the same conditions with DF, RME and their blends (B30 and B50) with bioethanol admix. Hourly fuel

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Characterization of Multifuel Eco-Blend (Diesel–Biodiesel–Bioethanol) …

211

consumption rates and exhaust emission level was established while loosening stubble (Table 8). Soil moisture in the stubble was 17, hardiness – 810 kPa [50]. In analyzing the data collected while the tractor was working in the field, it was possible to distinguish between the times that the tractor was traveling to or between fields, and when it is working within the field. In order to make useful comparisons between the fuels it was necessary to focus on the operation of the tractor within the field. Therefore only the on–field work segments were selected for further analysis [50]. Other factors also affected the loading on the engine, such as work rate and implement settings. With regard to implement settings, the tractor driver had considerable experience in driving tractors and setting up implements and he made a special effort to ensure that the implements on test drives were adjusted so that they had the same settings with particular reference to shank depth in the soil [50]. The lowest comparative fuel consumption of the tractor unit was achieved at average revolution speed of the engine‘s crankshaft (1200–1600 min-1) and at full load, often near the maximum torque mode. The highest comparative fuel consumption was achieved when the engine operated at high frequency of crankshaft revolutions and at slimed down engine load. During the on–field tests it was established that the optimum amount of ethanol to the basic fuel was 5 % and the amount of biodiesel in the blend – 30 % [50]. Admittedly, in a diesel engine, as a result of fuel injection into a cylinder, fuel–air distribution is not homogeneous therefore the process of particulate matter formation is controlled by mixing air and fuel. Final effects depend also on the condition of the engine, type of combustion chamber, conditions and indicators of its work, as well as on differences in physicochemical properties of fuel. Though, the utilize of DF and RME blends containing as little as 5.0–7.5% of bioethanol can yield benefits for tractor engine‘s work environment, resulting from exhaust particulate matter reduction (Figure 11a). The highest decrease of PM was established (see Figure 11b) when diesel engine developed the maximum traction force. 5 % bioethanol additive to B30 reduced PM emission by 15 % and CO – 1.0-1.5 % (see Figure 11c). CO emissions of the blends were not much different from that of conventional diesel. The addition of oxygenates into the diesel fuel resulted in only a slight effect on CO emissions at low, medium and high loads [12]. The blends that contained a higher percentage of bioethanol additives distinguished for higher CO emission. On the other hand, it was also observed that the blends containing a higher percentage of RME will have lower CO mission. This indicates that the presence of bioethanol might be the essential factor for the increase of CO emissions. The injection of B30 blend enriched with small doses of bioethanol is preferable since it incurs no changes to the engine and also results in suppression of thermal NOX and particulate levels (Figure 11b). It is believed that when such a compound is introduced in a region which is O2 deficient, there is an abundance of OH radicals which leads to particulate oxidation in addition to lower thermal NOX formation. Thermal NOX formation describes the process when nitrogen, N2, in the combustion air reacts with oxygen, O2, in the combustion air to produce NOX [9, 53]. This process is best studied and understood. The formation is exponentially dependent on the temperature. Because the process is very nonlinear, so called hot spots, local areas with higher temperature than the average temperature, can give very large effect on the amount of NOX produced. The maximum rather then, the average temperature is therefore very important and the process is very hard to predict accurately

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

212

Laurencas Raslavičius and Žilvinas Bazaras

because of this. Other important factors in thermal NOX formation are the residence time, which describes how long time the combustion gas is having the high temperature [53].

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4

1.3 1.3 1.4 1.2 1.2 1.2 1.4 1.3 1.3 1.8 1.8 2.0 1.9 1.8 1.9 2.0 1.9 2.0 2.1 2.0 2.1 2.2 2.0 2.1 2.1 2.2 2.1 2.8 2.8 2.7 2.7 2.6 2.7 2.6 2.6 2.7

8.1 8.0 7.9 7.9 7.8 7.8 7.8 8.1 8.0 6.2 6.1 6.1 6.0 6.0 6.0 6.1 5.9 6.0 5.1 5.1 5.0 5.0 4.9 5.2 5.1 4.9 5.0 3.2 3.0 3.1 3.0 3.1 3.0 2.9 2.8 3.0

SFC, g kW-1 h-1

10.5 10.4 11.1 9.5 9.3 9.3 10.9 10.5 10.4 11.2 11.0 12.2 11.4 10.8 11.4 12.2 11.2 12.0 10.7 10.2 11.0 11.0 10.3 10.9 10.7 10.8 11.0 8.6 8.4 8.4 8.1 8.4 7.8 7.5 7.3 8.1

Basic types of fuel

DF

0

228

5

B30 Admix of bioethanol (v/v), %

10

0

5

10

0

Slippage, %

Maximum traction power, W

Maximum traction force resistance, kN

Operating speed, m/s

Gear

Table 8. Operating parameters of T25A tractor while loosening stubble [51, 52]

B50

5

10

224 230

233 231

237 261

255 264

211 206

215 220 218 225

248 253

213

244

208 218

224 220

229 250

246 255

230 225 230 245

241

250 268

263 273

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

12.1 12.0 11.9 12.2 11.9 12.2 11.9 11.5 12.0 7.5 7.6 7.0 7.1 7.5 7.5 7.1 7.1 7.0 6.2 6.0 6.1 6.0 6.5 6.9 6.8 6.4 6.2 5.1 4.7 5.0 5.3 5.1 4.6 4.8 4.5 4.8

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Characterization of Multifuel Eco-Blend (Diesel–Biodiesel–Bioethanol) …

213

Figure 11. Dependence of the emission level on traction force and fuel compound (at maximum traction power): a – NOX; b – PM; c – CO; d – HC. Basic types of fuel: 1 – DF, 2 – B30, 3 – B50. 1‗, 2‗, 3‗ – basic types of fuel with admix of bioethanol of 5% (v/v); 1―, 2―, 3― – basic types of fuel with admix of bioethanol of 10% (v/v).

The turbulence and the amount of excess oxygen are two other important factors. The investigations carried out under operating conditions showed that 18 kW capacity tractor fuelled with biodiesel and DF/RME blends with bioethanol had a higher amount of NOX in exhaust gases (Figure 11b). At every diesel proportion (30 % and 50% by volume), it can be observed that all fuel blends increased NOX significantly relative to diesel fuel [54–56]. Normally, if we can create a more complete combustion, we can get a higher combustion temperature, which will cause high NOX formation. Therefore, adding 10% of bioethanol (v/v) to DF/RME blend as oxygenate causes a small increase of NOX (4.5–5.0 %) level in exhaust emission. The concentration of unburned HC depends on the amount of fuel injected during the ignition delay period. As this period is shorter for the tested biofuels, due its higher Cetane number, hydrocarbon emissions decrease correspondingly. Accordingly, blends containing a higher percentage of RME distinguish for lower HC emission. At the small loads of CI engine, DF, RME, and bioethanol admixed B30 and B50 had higher HC emissions than those emitted from medium or higher loads (Figure 11c). The reason is that, normally, better

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

214

Laurencas Raslavičius and Žilvinas Bazaras

combustion can be achieved at a medium speed and with a medium–sized load. Fuelling 18 kW capacity tractor unit with B30+5%E blend, emission of hydrocarbons was reduced by 24– 26 % (Figure 11c).

CONCLUSIONS Optimizing the combustion process through options such as improved combustion chamber design and high–pressure fuel injection systems promises significant reductions in engine–out emissions. Combining of such strategies with advanced after–treatment and electronic control systems promises that the diesel engine has the potential to emerge as the environmentally friendly, fuel economical power unit of the future. Nevertheless, assessing the great number of available options and their optimum combination is a very time–intensive task that needs to be addressed through a smart combination of experimentation and analysis. Undoubtedly, carefully conducted experiments can provide relatively precise results for a specific test. The summing–up conclusions reached in the present study are as follows: 

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.











Striving for improvement of the combustion process of oxygenated fuels while omitting any regulatory adjustment, leads to combining of bioethanol and rapeseed methyl ester to compound the fossil diesel. On the basis of the Q–S (quasi-steady) model of the inert warming-up of hydrocarbon fuel drop, an equation for calculating ignition delay time was deduced and adapted for establishing the inflammation characteristics of multifuel combustible eco–blends and forecasting the possibilities of using them in the unmodified diesel engines. The experimental multifuel drop combustion trial proved the results of mathematical modeling achieved in the theoretical part, which showed that in contrast to RME, bioethanol additive can reduce ignition delay of biodiesel blends. During the break-stand experiments of the CI engine D144, it was established that, a shared volume of the 7.5% of bioethanol to compound B30 indicated specific fuel consumption rates commensurate with fossil diesel ones. A shortage of most of the fatty acid methyl esters to increase fuel consumption of diesel engines was eliminated through the combining of the multifuel compounds alone. In comparison to B30, a newly derived combustible blend B30+7.5E demonstrated fairly improved emissions of exhaust gases. For low load mode: PM (–10%), NOX (– 2%), CO (–20%), HC (–12.5%). For average load mode: PM (–10%), NOX (–2%), CO (–22%), HC (–14.5%). For high load mode: PM (–18%), NOX (–3.5%), CO (– 22%), HC (–18%). The on-field experiments revealed that the optimum amount of bioethanol (v/v) in the basic DF/RME blend was 5% and the amount of RME – 30%. Since evaluation of the bioethanol admix of 7.5% (v/v) was not included to in the on-field test methodology, the obtained results coincided very well with those received during the breake-stand experiments.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Characterization of Multifuel Eco-Blend (Diesel–Biodiesel–Bioethanol) … 

215

The modifications of CI engines are not required to use B30+7.5E eco-blend as a fuel. Using of bioethanol admix of 10% (v/v) for B30 is not recomendable due to uneven engine operation.

The proposed fuel blends B30+5E and B30+7.5E are expedient to use in the areas especially sensitive to environmental pollution (forestry, ecological farms, etc.). The investigated multifuel eco-blends are suitable to be used in part in public urban transport and navigation.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

REFERENCES [140] Nylund N.O., Niemi S., Paanu T., Berg R., 2005. Alcohols/ethers as oxygenates in diesel fuel: Properties of blended fuels and evaluation of practical experiences. Report TEC 3/2005. [141] Raslavičius L., Bazaras Ž., 2010. The possibility of increasing the quantity of oxygenates in fuel blends with no diesel engine modifications. Transport 25(1):81–88. [142] Pinzi S., Garcia I.L., Lopez-Gimenez F.J., Lugue de Castro M.D., Dorado G., Dorado M.P., 2009. The ideal vegetable oil-based biodiesel composition: A review of social, economical and technical implications. Energy & Fuels 23:2325–2341. [143] Van Gerpen J.H., Johanson L.A., Hammond E.G., Marley S.J., 1995. Determining the optimum composition of a biodiesel fuel. The Iowa Soybean Promotion Board, pp. 51. [144] Schumacher L.G., Madzura T., 1997. Lessons learned while fuelling with biodiesel, in: Proceedings of Commercialization of Biodiesel: Producing a Quality Fuel, pp. 197– 208. [145] Sinha S., Agarwal A.K., 2010. Experimental investigation of the effect of biodiesel utilization on lubricating oil degradation and wear of a transportation CIDI engine. Journal of Engineering for Gas Turbine and Power, Transaction of ASME (in press). [146] Bora D.K., Das L.M., Babu M.K.G., 2010. Wear and tear analysis of a single cylinder diesel engine using karanja biodiesel (B20) after 512 hours. Journal of Scientific and Industrial Research 63:639–642. [147] Lebedevas S., Vaicekauskas A., Suskov P., 2007. Presumptions of effective operation of diesel engines running on RME biodiesel. Research on kinetics of combustion of RME biodiesel. Transport 22:126–133. [148] Raslavičius L., Bazaras Ž., 2010. Variations in oxygenated blend composition to meet energy and combustion characteristics very similar to the diesel fuel. Fuel Processing Technology 91(9):1049–1054. [149] Agarwal A.K., Bijwe J., Das L.M., 2003. Effect of biodiesel utilization of wear of vital parts in compression ignition engines. Journal of Engineering for Gas Turbine and Power 125:604–612. [150] Van Gerpen J.H., 1996. Cetane number testing of biodiesel, In: Cundiff J.S. (Ed.), Liquid fuels and inddustrial products from renewable resources, in: Proceedings of the 3rd Liquid Fuel Conference. St. Joseph: American society of agricultural engineers (ASAE), pp. 197–206.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

216

Laurencas Raslavičius and Žilvinas Bazaras

[151] Kwanchareon P., Luengnaruemitchai A., Jai-In S., 2007. Solubility of a dieselbiodiesel-ethanol blend, its fuel properties, and its emission characteristics from diesel engine. Fuel 86:1053–1061. [152] Mittelbach M., Remschmidt C. Biodiesel: A comprehensive handbook, first ed., Boersedruck Ges.m.b.H, Vienna, 2004. [153] Rakopoulos C.D., Antonopoulos K.A., Rakopoulos D.C., Hountalas D.T., Giakoumis E.G., 2006. Comparative performance and emissions study of a direct injection diesel engine using blends of diesel fuel with vegetable oils or bio–diesels of various origins. Energy Conversion and Management 47:3272–3287. [154] Feldman M.E., Peterson C.L., 1992. Fuel injector timing and pressure optimization on a DI diesel engine for operation on biodiesel, in: Liquid fuels from renewable resources: Proceedings of an Alternative Energy Conference. ASAE Publication, Nashville, TN, USA, pp. 111–123. [155] Reece D.L., Peterson C.L., 1993. A report on the Idaho on-road vehicle test with RME and neat rapeseed oil as an alternative to diesel fuel. ASAE Paper, 93–5018. [156] Takesawa Y., 1993. Study on palm oil for diesel substitute, in Vegetable oils as transport fuels: Proceedings of Seminar. FAO Press, Pisa, Italy, pp. 31–35. [157] Peterson C.L., Reece D.L., Hammond B.J., Thompson J., Beck S.M., 1994. Processing, characterization and performance of eight fuels from lipids. ASAE Paper 946531. [158] Peterson C.L., Reece D.L., 1994. Emissions tests with an on–road vehicle fuelled with methyl and ethyl esters of rapeseed oil. ASAE Paper 946532. J. [159] Vellguth G., 1983. Performance of vegetable oils and their monoesters as fuels for Diesel engines. SAE Paper 831358/30. [160] Liubarskis V., Raslavičius L., 2008. Research into ignition process of the diesel fuel and its blends with rapeseed methyl ester and ethanol, in: Proceedings of the 6th International Conference on Power Supply and Energy Efficiency in Agriculture (Section No 4: Renewable Energy Sources. Local Energy Sources. Ecology). Moscow, 13–14 May 2008, The All–Russian Scientific Research Institute for Electrification of Agriculture (VIESH), p. 396–401. (in Russian). [161] Kopeyka A.K., Golovko V.V., Zolotko A.N., Darakov D.S., Liubarskij V.M., Raslavičius L., 2008. Inflammation and combustion of the multi–component biofuels, in: Proceedings of the 6th Minsk International Heat and Mass Transfer Forum MIF–VI (Section No 4: Heat and Mass Transfer in Chemically Reactive Systems). Minsk, 19–23 May 2008, A.V. Luikov Heat and Mass Transfer Institute of National Academy of Sciences of Belarus. (in Russian) www.itmo.by/ forum/mif6/program(rus).pdf. [162] Raslavičius L. Research into three–component combustible mixture application for fuelling diesel engines. Ph.D. thesis: Kaunas University of Technology; 2009. [163] Law C.K., 1982. Recent advances in droplet vaporization and combustion. Progress in Energy and Combustion Science 8(3):171–201. [164] Raslavičius L., Bazaras Ž., 2010. Prediction of multi–component effects on ignition delay of oxygenated diesel fuel blends. Indian Journal of Engineering and Materials Sciences 17(4):243–250. [165] Janulis P., Makarevičienė V., Sendžikienė E., 2005. Solubility in multi-component fuel systems. Bioresource Technology 96(5):611–616.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Characterization of Multifuel Eco-Blend (Diesel–Biodiesel–Bioethanol) …

217

[166] Szklo A., Schaeffer R., 2006. Alternative energy sources or integrated alternative energy systems? Oil as modern lance of peleus for the energy transition. Energy 31:2513–2522. [167] LST EN 590:2009 Automotive fuels – Diesel – Requirements and test methods. [168] LST EN 14214:2009 Automotive fuels – Fatty acid methyl esters (FAME) for diesel engines – Requirements and test methods. [169] LST EN 1537:2008/P:2009. Automotive fuels – Ethanol as a blending component for petrol – Requirements and test methods. [170] Varshavsky G.A., 1945. Combustion of liquid fuel drop. Diffusion theory. Moscow: Trudy BNT NKAP (Бюро Новой Техники (БНТ) Народного Комиссириата Авиационной Промышленности (НКАП)) No 6, p. 87–106. (in Russian). [171] Варшавский Г.А., Федосеев Д.В., Франк-Каменецкий Д.А., 1966. Квазистационарная теория воспламенения капли жидкого топлива. Физика аэрозолей (Киев, СССР) 1:101–107. [Varshavsky G.A., Fedoseev D.V., FrankKamenecky D.A., 1966. Quasi–steady theory of the ignition of liquid fuel drop. Physics of Aerosoles (Kiev, USSR) 1:101–107.] (in Russian). [172] Raslavičius L., Liubarskis V., 2007. Reasoning of mathematical model efficiency, composed for identification of optimal ethanol quantity additive to biodiesel fuels, in: Proceedings of the 12th International Conference on Technical and Technological Progress in Agriculture. Raudondvaris, 20–21 September, 2007. IAE LUA, p. 197–201. [173] Williams A., 1973. Combustion of droplets of liquid fuels: A review. Combustion and Flame 21:1–31. [174] Bergeron C.A., Hallett W.L.H., 1989. Ignition characteristics of liquid hydrocarbon fuels as single droplets, Canadian Journal of Chemical Engineering 67:142–149. [175] Bergeron C.A., Hallett W.L.H., 1989. Autoignition of single droplets of two-component liquid fuels. Combustion Science and Technology 65:181–194. [176] Hallett W.L.H., Ricard M.A., 1992. Calculations of the auto-ignition of liquid hydrocarbon mixtures as single droplets. Fuel 71(2):225–229. [177] Williams T.J., 1971. Diesel fuel properties for combustion calculations. International Journal of Mechanical Sciences 13:803–812. [178] Misic D., Thodos G., 1961. The conductivity of hydrocarbon gases at normal pressures. The AIChE Journal (American Institute of Chemical Engineers) 7:264–271. [179] Vargaftik N.B. Handook of thermophysical properties of gases and liquids, 1st ed., Nauka, Moscow, 1972. (in Russian). [180] Kay W.B., 1936. Density of hydrocarbon gases and vapors at high temperature and pressure. Industrial and Engineering Chemistry 28:1014–1019. [181] Thomas L.H., 1946. The dependence of the viscosities of liquids on reduced temperature and a relation between viscosity, density and chemical constitution. Journal of the Chemical Society, Part II, p. 573–579. [182] Hilsenrath J., Beckett C.W., Benedict W.S., Nuttall R.L., Touloukian Y.S., Woolley HW et al., 1956. Tables of thermal properties of gases. Journal of the Electrochemical Society 103:124–125. [183] Kopeyka A.K., Golovko V.V., Brovchenko V.I., Darakov D.S., 2002. The ignition of a single drop of canola-methyl ester. Fizika Aerodispersnikh Sistem (Physics of Aerodispersed Systems) 39:103–108. (in Russian).

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

218

Laurencas Raslavičius and Žilvinas Bazaras

[184] Yuan W., Hansen A.C., Zhang Q. 2003. Predicting the physical properties of biodiesel for combustion modelling. Transactions of the American Society of Agricultural Engineers (ASAE) 46:1487–1493. [185] Reid R.C., Prausnitz J.M., Poling B.E. The properties of gases and liquids, 4th ed., McGraw–Hill, New York, 1987. [186] Huber M.L., Lemmon E.W., Kazakov A., Ott L.S., Bruno T.J., 2009. Model for the thermodynamic properties of a biodiesel fuel. Energy & Fuels 23, 3790–3797. [187] Kurbatov V.A., 1989. Generalization of experimental data on thermal conductivity of paraffin series hydrocarbons and alcohols. Journal of Engineering Physics and Thermophysics 56:694–699. [188] Dillon H.E., Penoncello S.G., 2003. A fundamental equation for the calculation of the thermodynamic properties of ethanol, in: 15th Symposium on Thermophysical Properties (June 22–27, 2003), Boulder, Colorado, USA, pp. 1–17. [189] Araya K, Yoshido T., 1985. Single droplet combustion of sunflower oil (Part I). Journal of Senshu University-Hokkaido (Natural Science) 18:83–99. [190] Raslavičius L., Bazaras Ž., 2009. The analysis of the motor characteristics of D–RME– E fuel blend during on-field tests. Transport 24(3):187–191. [191] Kraujalis A., Liubarskis V., Raslavičius L., 2005. Biodiesel and their blends with mineral diesel consumption analysis fuelling tractors of small and average capacity. Journal of Research and Applications in Agricultural Engineering 50(1):45–48. (in Russian). [192] Liubarskij V.M., Raslavičius L., 2005. The analysis of fuel consumption rates for the tractors of small and average capacity, in: Proceedings of the International Field– Scientific Conference of the Junior Researchers on Research Methods and Engineering Work Results for Resource–Saving Technologies in Agriculture [Методы исследований и результаты разработок техники для ресурсосберегающих технологий сельского хозяйства] (Collected papers, vol. 1), Minsk, 2005, p. 38–44. (in Russian). [193] Schwerdt C., 2007. Modelling NOX–Formation in Combustion Processes. Master Thesis, Lund Institute of Technology, pp. 42. [194] Raslavičius L., Bazaras Ž., 2010. Ecological assessment and economic feasibility to utilize first generation biofuels in cogeneration output cycle – The case of Lithuania. Energy 35(9):3666–3673. [195] Raslavičius, L., Strakšas, A., 2011. Motor biofuel-powered CHP plants – a step towards sustainable development of rural Lithuania. Technological and Economic Development of Economy 17(1): 189–205.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

In: Liquid Fuels: Types, Properties and Production Editor: Domenic A. Carasillo

ISBN 978-1-61470-435-5 © 2012 Nova Science Publishers, Inc.

Chapter 7

PRODUCTION OF RENEWABLE LIQUID FUELS USING DIFFERENT FUEL PROCESSING METHODS N. R. Banapurmath,1 V. S. Yaliwal,2 R. S. Hosmath,1 Y. H. Basavarajappa,3 N. M. Girish,1 A. V. Tumbal,l and P. G. Tewari1

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

1

Professor, BVB College of Engineering and Technology, Hubli, India 2 Sr. Gr. Lecturer, SDM College of Engineering and Technology, Dharwad, India 3 Assistant Professor, Tontadarya College of Engineering and Technology, Gadag, India

ABSTRACT Now a day‘s use of biofuels for both power generation and automobiles is more relevant because of the need for energy security, environmental concerns, foreign exchange savings and socio-economic issues. Non-edible oils are considered as second generation alternative fuels and use of these oils avoids conflict between food and energy security. Therefore various locally available vegetable oils of edible and non- edible nature were selected for their biodiesel production. The edible oils selected include sunflower, rice bran, palm, coconut oils while non- edible oils include Honge, Jatropha, Neem, and Mauha oils. Subsequent characterization of these biodiesels was carried out to ensure their suitability as alternative fuels in diesel engines. The non- edible oils have high free fatty acid (FFA) content and they pose some problems when used directly in an engine as a diesel substitute. The physico-chemical properties of vegetable oil affect the engine performance and emission characteristics. These are all attributed to their larger molecular mass, chemical structure, higher viscosity, low volatility and poly unsaturated character. Therefore in order for them to be used as fuels in diesel engines they require appropriate fuel processing methods. Various methods have been used and reported in the literature for fuel processing. These methods are base and acid catalyzed, continuous microwave assisted, ultrasonic, pressure reactor based, supercritical methanolysis,

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

220

N. R. Banapurmath, V. S. Yaliwal, R. S. Hosmath et al. enzyme catalyzed, and heterogeneous catalyzed transesterification methods. In this study, the biodiesel production from vegetable oils was carried out using base and acid catalyze, continuous microwave assisted transesterification and pressure reactor methods. Subsequently characterization of both raw vegetable oils and their respective biodiesels was done according to ASTM standards. The study on renewable liquid fuels suggests that non- edible oils take longer time for their respective biodiesel productions because of their higher free fatty acid (FFA) content. The experimental investigation also suggests that the fuel processing with conventional transesterification method is a laborious and time consuming one. On the other hand MACTM is found to be better in terms of shorter reaction time, lower consumption of power and resources compared to conventional transesterification process. MACTM method reduces the reaction time drastically for both edible and nonedible oils. For edible oils the reaction time is found to be 1 minute while for non-edible oils it varies from 3 to 6 minutes. The biodiesel production from pressure reactor uses same resources required by the conventional transesterification method [CTM], but it is conducted in a closed vessel. This feature enhances the chemical kinetics, thereby reducing the reaction time up to 66 % compared to conventional method. Major safety precautions were taken during the tests of biodiesel production with pressure reactor. However, this method suffers from limitation on increasing reactor pressure. The properties of all the oils were determined and compared with diesel fuel. It is also worth noting that the biodiesels if stored for a longer (six months) time gains higher viscosity associated with changes in other fuel properties. Oxidation stability of the biodiesel plays an important role in ensuring its suitability as alternative to diesel fuel. In view of this, oxidation stability of some of the biodiesels was considered in this study.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Keywords: Biodiesel, non-edible oil, Microwave assisted transesterification, Pressure reactor, oxidation stability

1. INTRODUCTION India is said to be one of the seven largest consumers of energy, but the growing gap between consumption and domestic output is a cause of concern. India‘s share in global oil reserves is about 0.5 per cent, whereas its share in global consumption is about 3 per cent. India is still dependent to the extent of 30 to 35 per cent on non-commercial fuel sources like vegetable oils, cow dung, firewood, agricultural waste, etc [1]. Using vegetable oils in a diesel engine is not a new idea. Rudolph Diesel ran diesel engine with use of peanut oil during the late 1800 [2]. The contribution of biofuels (vegetable oils) in the use of total renewable energy is very less. But energy from biofuels cannot be neglected because India is a land of agriculture and made up of 5, 80,000 villages approximately and seventy percentage of the population depends upon agriculture for their living. Therefore it results in benefits for agricultural and rural development, including generation of new jobs and income as well. The move from fossil fuels to biofuels will create new industries and bring increased economic activity. Moreover; Indian formers have got rich experience of managing commercial energy plantations in varied climatic condition. India‘s biofuel policy is looking at ways to limit rising oil imports by promoting use of bio-fuels as an alternative renewable source of energy. At present, it is estimated that India will be able to produce 288 metric tons of biodiesel by the end of 2012, which will supplement 41.14% of the total demand of diesel fuel

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Production of Renewable Liquid Fuels Using Different Fuel Processing Methods

221

consumption [3, 4]. Therefore, use of biofuels such as vegetable oils, in compression ignition (CI) engine and other applications prove more relevant in the present energy scenario [4]. Sincere and untiring efforts need to be made by scientists and researchers in exploring the possibilities of harnessing energy from renewable energy sources [5]. Because they are renewable, non-toxic, biodegradable, sulfur free, carcinogenic ring components free and have low emission profiles [6, 7, 8, 9]. Even though non-edible oils such as Honge, Neem, Mahua and Jatropha oils are available abundantly in India, biodiesel production is not popular. Because of this reason, the Government of India has announced many facilitating policies in respect of various alternative fuel technologies and systems. In Karnataka state, currently 1400 out of 7000 government busses are running on ethanol–diesel blends and it is planned to upgrade the same to 5000 buses soon. From the literature survey, it is observed that many countries around the world are using edible oils for engine applications. In USA and Europe, their surplus edible oils like soybean, sunflower and rapeseed oils are being used as feed stock for the production of biodiesel [10, 11, 12, 13]. Only renewable fuel from oil crops are not considered as sustainable. Because of growing population, there always exist a great demand for edible oil consumption and hence it becomes too expensive for engine and other applications. However, the use of second and third generation fuels lead to a sustainable development. During the investigation and with a suggested priority structure, biodiesel from non –edible oils and algae is found to be in the highest rank and better alternative fuel compared to first generation fuels. Biodiesel production by transesterification is achieved with use of methanol and ethanol in the presence of alkali catalysts [14]. Biodiesel production by using ethanol instead of methanol has an advantage of increasing agricultural benefit and the extra carbon brought by ethanol molecule slightly increases the heating value and cetane number [15]. This biodiesel can be used conveniently in a diesel engine. Short term engine tests using neat vegetable oils as a fuel showed encouraging results. However, longer duration tests poses many problems These problems are attributed to high viscosity, low volatility and polyunsaturated character of neat vegetable oils [16, 17, 18]. Some of the common problems of vegetable oils in diesel engines in the long run are coking and trumpet formation on the injectors, carbon deposits, oil ring sticking, and thickening and gelling of lubricating oil as a result of contamination by the vegetable oils [17, 18]. These problems can be reduced, if the neat vegetable oils are chemically modified to biodiesel, which is similar in characteristics to diesel fuel. Biodiesel is defined as a liquid hydrocarbon fuel composed of fatty acids monohydric alcohol esters whose molecular composition may change according to the type of feed stocks and from where the feed stock can be obtained i.e. from different places for the fuel synthesis [19]. Differences in the molecular structure of oil greatly influence the physical and chemical processes occurring during the atomization, vaporization, spray pattern and combustion of the fuel after it is injected into the combustion chamber of diesel engine [19]. Therefore, for long runs, use of biodiesel or methyl/ethyl esters is more suitable. Y.C. Sharma, et.al [20] studied the recent developments in biodiesel technology and characterization of biodiesel. They showed that the biodiesel is the solution for future. In this direction, many researchers have identified several methods to produce biodiesel such as base and acid catalyzed transesterification, two step transesterification, supercritical methanolysis, microwave assisted transesterification, ultrasonic transesterification, lipase catalyzed transesterification, biodiesel production by using heterogeneous catalysts [21, 22, 23, 24, 25, 26, 27]. But all these methods may consume more time or costly. Young choel bak, et al [28], Vivek and Guptha

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

222

N. R. Banapurmath, V. S. Yaliwal, R. S. Hosmath et al.

[29], L.C. Meher, et.al [30], Laureano Canoira, et.al [31], Ertan Alptekin, et.al [32], T. Eevera et.al [33] all developed a system for biodiesel production and conducted the process of transesterification using different non-edible oils and determined the optimum process parameters in terms of reaction temperature, molar ratio, amount of catalyst. Hideki Fukuda et al, [34] studied the production of bio-diesel using different methods and shown their merits and demerits and reported that among many methods, transesterification using alkali-catalysts give high levels of conversion of triglycerides to their corresponding methyl esters in short reaction times. Ayhan Demirbas [35] has produced methyl and ethyl esters from linseed oil with transesterification reaction in non-catalytic supercritical fluid conditions. Zlatica J. Ahn, et al. [36], Predjević [37] and Xin Deng, et.al [38] have reported biodiesel production using two reaction processes for different vegetable oils. Yun Liu et.al [39] studied the preparation of biodiesel from stillingia by enzymeic transesterification with methanol. The results showed that lipase type, reaction systems and operational parameters influenced the biodiesel yield. From the literatures, it is observed that, identifying the physical and chemical properties of vegetable oil such as viscosity, free fatty acid composition (FFA), acid value, chemical structure etc is important for determining the suitability of the vegetable oil for transesterification process; this can be performed to get better conversion and properties of the biodiesel [22]. The transesterification method has been found to be the most effective, low cost and viable one for the production of biodiesel. But higher FFA content of oil makes the biodiesel production more difficult [40]. Researchers have carried out two steps pretreatment to reduce high FFA less than one percent, the transesterification reaction was completed with an alkaline catalyst to produce biodiesel. Microwave assisted transesterification method offers many advantages in terms of lower reaction time, reduced catalyst requirement and lower alcohol/oil ratio. In this method, less that 0.2% (weight basis) catalyst, 5:1 to 9:1 molar ratio was used. The process was conducted at 60 – 700C for 10 – 20 minutes. From which, about 95- 98% conversion can be obtained. Zlatica J. Predojević [41], Ahn, et al. [42] and Xin Deng, et.al [38] produced biodiesel using two reaction process for different vegetable oils. Nezihe Azcan, et.al [43] studied microwave assisted transesterification of rapeseed oil. Their results indicated that microwave heating has effectively increased the biodiesel yield and decreased the reaction time. Y.C. Sharma, et.al [44] has studied the recent developments in biodiesel technology and characterization of biodiesel and they found that the biodiesel is the solution for future. Naoko Ellis et.al [45] studied the transesterification process and observed the progress of their reaction using in situ viscometer. In view of this, an attempt has been made to develop the microwave and pressure based reactors for biodiesel production. The present study was conducted mainly to carry out simple, low cost and efficient transesterification process using pressure reactor. The experimental results show that these methods take very less time of about 20 minutes with pressure of 25 bar and it saves 66% of power consumption. In MACT method the reaction time is further reduced from several hours to less than a minute. Physical and chemical properties of both edible and non-edible oil were determined in the college laboratory and at Bangalore Test House, Bangalore, India. From the study, it is observed that, the properties of biodiesel prepared by microwave and pressure based reactors are found to be same as that biodiesel produced from conventional transesterification process.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Production of Renewable Liquid Fuels Using Different Fuel Processing Methods

223

2. CHEMICAL REACTION DURING CONVENTIONAL TRANSESTERIFICATION OF VEGETABLE OILS

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Transesterification is the chemical process of converting vegetable oils into diesel like fuel. In transesterification process, a triglyceride reacts with three molecules of alcohol in the presence of a catalyst, producing a mixture of fatty acids and glycerol (Figure 1). A specified amount of methanol or ethanol is mixed and allowed to react with the vegetable oil in the presence of a catalyst like NaOH or KOH at a temperature of 700C. Conversion of vegetable oil to biodiesel is affected by different parameters namely time of reaction, reactant ratio (Molar ratio of alcohol to vegetable oil), type of catalyst, amount of catalyst, temperature of reaction. To complete a transesterification process stoichiometrically, 3:1 molar ratio of alcohol to triglycerides is needed. However, in practice, higher ratio of alcohol to oil ratio is generally employed to obtain biodiesel of lower viscosity and high conversion. The effect of transesterification is to reduce the level of free fatty acid (FFA) greatly and reduce the viscosity, boiling point, flash point and for removal of the complete glycerides from the vegetables oils. In the process cetane number is also improved. It has been reported that the methyl ester of vegetable oils offers low smoke levels and high thermal efficiencies than neat vegetable oils.

Figure 1. Transesterification reactions.

3. MATERIALS AND METHODS 3.1. Materials Edible oils of sunflower, palm, coconut and rice bran oils have free fatty acid [FFA] content of less than 1 % and are therefore easy to produce their respective biodiesels. On the other hand non- edible oils of Honge, Jatropha, Neem and Mahua oils have comparatively higher free fatty acid [FFA] compared to edible oils. The detailed transesterification method for Honge oil is only reported here as the process is more or less similar in all the cases. The materials required for Honge oil biodiesel production include NaOH, methanol/ethanol, Na2SO4 (Figure 2). Initially the FFA content of Honge oil was measured by standard titration methods which had an acid value of 4. This is slightly higher than the required value of 1%

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

224

N. R. Banapurmath, V. S. Yaliwal, R. S. Hosmath et al.

limit for satisfactory transesterification reaction. Therefore FFA values are first reduced in a multistep pretreatment process using acid catalyst (H2SO4, 1% v/v) to reduce the acid value below 1%. Then the Honge oil sample was heated to about 1000C, at which all moisture was evaporated. The transesterification set up is shown in Figure 3.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Figure 2. Methanol, Sodium hydroxide, Sodium Sulfate and Silica gel containers.

Figure 3. Equipment for Transesterification.

For the pressure reactor method of transesterification the reactor was designed as per the ASTM standards (Figure 4). The pressure reactor was than fabricated. The diameter, thickness and height of the reactor were determined taking safety precautions into the design procedure. The designed values of diameter, thickness and height of pressure reactor were found to be 5.4 inch, 3 - 3.5 mm and 12 inches respectively. The pressure gauge, temperature gauge and safety valves are attached to the pressure reactor for monitoring the pressure and temperature.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Production of Renewable Liquid Fuels Using Different Fuel Processing Methods

225

Figure 4. Schematic diagram of fuel processing device (pressure reactor): 1 - Temperature gauge 2 Pressure gauge 3 - Inlet/ Outlet 4 - Reactor 5 -Stirrer 6 -Electric Heater with temperature control.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

In the MACT method, a house hold 800 W 2450 Hz, microwave (kenstar) was modified to act as a biodiesel reactor as shown in Figure 5. Following are the main parts of the reactor: (a) Oil reservoir (b) methanol reservoir, (c) oils pump, (d) alcohol pump (e) tee connector, (f) reactor coil, (g) microwave oven, (h) product reservoir.

Figure 5. Continuous Microwave assisted transesterification method for palm biodiesel preparation.

4. RESULTS AND DISCUSSIONS The physical, chemical and thermal properties of vegetable oil such as viscosity, volatility, higher fatty acid content limit the direct application of vegetable oils in a diesel engine. Therefore even today, many of the scientists are still working on fuel processing or engine hardware modification. In this context, many researchers have established many new methods of fuel processing. This section presents the results and discussions under three headings on biodiesel production methods, chemical composition of vegetable oil and its structure and fuel processing.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

226

N. R. Banapurmath, V. S. Yaliwal, R. S. Hosmath et al.

4.1. Biodiesel Productionmethods

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

4.1.1. Conentional Transesterifiction Method Edible (coconut oil, palm oil, rice bran oil, and rice bran oil) and non-edible (pongamia, Jatrophs oil, mauha oil and neem oil) oils were used in this study. This process is reported only for sunflower and Honge oil. The oils were first filtered by using cloth and centrifugal filter mainly to remove the fine dirt and other unwanted materials from the raw vegetable oil and then 20 % (wt) sodium sulfate powder was added to oil for 20-25 minutes. This absorbs the moisture from the oil and then placed in a reactor equipped with magnetic stirrer, and thermometer. Under agitation the raw oil was heated up to nearer to the boiling point to remove the moisture present in the vegetable oil. After that oil is allowed to cool down under room temperature, and the treated oil alone was taken for biodiesel production purpose. Again, under agitation, the above treated oil was heated up to a desired temperature on a hot plate.

Figure 6. Washing and moisture removal from HOME.

A fixed amount of freshly prepared sodium hydroxide–methanol solution was added into the oils, taking this moment as the starting time of the reaction. When the reaction reached the preset reaction time, heating and stirring were stopped. The products of reaction were allowed to settle overnight. During settling two distinct liquid phases were formed: crude ester phase at the top and glycerol phase at the bottom as shown in Figure 6. The crude ester phase separated from the bottom glycerol phase was then washed by cold or warm distilled water 23 times. After that weight of the ester was calculated. The reaction was investigated step by step. The optimal value of each parameter involved in the process such as reaction temperature, molar ratio, amount of catalyst were determined and these optimum process parameters were used to produce respective biodiesels. The complete experimental set up for transesterification process and other details are shown in the figures 2, 3, 4 and 5 respectivelly.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Production of Renewable Liquid Fuels Using Different Fuel Processing Methods

227

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

4.1.2. Biodiesel Production Using Low Capacity Laboratory Scale Pressure Reactor The second method was tried here and given below. This section also outlines design and development of low capacity pressure reactor for biodiesel production. This device was designed and developed to withstand up to 25 bar pressure. The pressure reactor for fuel processing is shown in the Figure 4. The materials used for production of Honge oil methyl esters are the same as used in conventional biodiesel production (transesterification) method. But in this present work, the process was conducted at different pressures and the yield was noted. The process was carried out in a small batch to ensure clean methyl/ethyl ester and to establish optimum conditions in terms of reaction time and pressure. Experimental investigations reported that, higher yield within a short time of 20 minutes can be obtained at higher pressure (25 bars) as shown in Figure 7. Each test batch require, one liter Honge oil, 18- 20 % by volume methanol/ethanol, 1% by weight NaOH pallets and 30% by volume of hot water (3 times). A system developed for fuel processing (transesterification) process using pressure reactor, reduces reaction time because of increased chemical kinetics and improves conversion efficiency.

Figure 7. variation of conversion with pressure.

Figure 8. Variation of conversion with time. Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

228

N. R. Banapurmath, V. S. Yaliwal, R. S. Hosmath et al.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

The yield was obtained up to 96% within a short time of 20 minutes as shown in Figure 8. In the present work, ethanol was also used to produce esters, but producing ethyl ester rather than methyl ester is more valuable because it is entirely agricultural fuel.

4.1.3. Microwave Assisted Continuous Transesterification Method In operation vegetable oil of palm oil and methanolic NaOH solution were fed separately via 2 pumps and mixed at the tee connector at the inlet. Reaction time and molar ratio of the oil to alcohol were controlled via a combination of flow control valves of the pumps such that for 1 LPM output of oil pump a mixture of 6 gm of NaOH dissolved in 240 ml of methanol should be pumped per minute from the other pump. The outlet was slightly bended upward to keep the reactor filled at all flow rates. The esters fraction (upper layer) was separated and washed twice with half volume of de-ionized water and dried over anhydrous sodium sulfate. Working set up is shown in Figure 5. Palm oil (vegetable oil) is stored in one container and methanol with crystals of NaOH in other container. The catalyst NaOH is dissolved into the methanol by vigorous stirring in a small reactor (for 240 ml of methanol 6 gm of NaOH is added). Most carboxylic acids are suitable for the reaction, but the alcohol should generally be a primary or secondary alkyl. Tertiary alcohols are prone to elimination, and phenols are usually too unreactive to give useful yields. Two gear pumps are used to pump palm oil and methanolic NaOH solution separately. Flow control valves (ball valve) used to control the flow rates of oil and methanolic NaOH solution. The reaction temperature attained during the transesterification in microwave oven is around 65-800C. Microwave energy is delivered directly to the reacting molecules, which undergo chemical reaction. Thus, heat transfer is more effective than conventional heat, which transfers from the environment. This instantaneous heating of oil mixture gives the advantages over the prolonged heating required in conventional heating (2 hrs). The product obtained is collected in conical separator for settling. A successful transesterification reaction produces two liquid phases: ester and crude glycerin. Crude glycerin, the heavier liquid, will collect at the bottom after several hours of settling as shown in Figure 2. Phase separation can be observed within 10 min and can be complete within 2 h of settling. Complete settling can take as long as 20 h. 4.1.4. Comparison of Biodiesel Quality with Both Methods The properties of biodiesel obtained with both methods were comparable and is listed in the table below. The yields obtained by the conventional batch transesterification were marginally higher compared to continuous microwave assisted biodiesel reactor methods as shown in the following Table 4.

4.2. Chemical Composition of Vegetable Oil and Its Structure In this section the chemical composition and structure of one of the vegetable oil i.e. Honge oil is only presented. The chemical composition and structure was measured at Bangalore Test House, Bangalore, India. Based on this, the Honge oil was studied. Vegetable oils are a mixture of organic compounds ranging from simple straight chain compared to complex structure of

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Production of Renewable Liquid Fuels Using Different Fuel Processing Methods

229

proteins and fat-soluble vitamins. They are usually triglycerides generally with a number of branched chains of different lengths [42, 43, 44, 45]. Triglycerides are the main constituents of vegetable oils. The fatty acid contribution in vegetable oils varies from oil to oil. Many samples of Honge oil were taken from different places and they vary in their Chemical structure [4]. It depends on weather and soil conditions. Fatty acid may be saturated or unsaturated depending on double bonds. The differences in geometry between the various types of unsaturated fatty acids as well as between saturated and unsaturated fatty acids play an important role in combustion and in the formation of exhaust emissions. Some of the fatty acids were bound or attached to other molecules, such as in triglycerides, when they are not attached to molecules, are called as free fatty acids [46]. Table 1. Fatty acid contribution of Honge oil sample and its chemical structure [4, 30, 56]

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Sl No 1 2

*

Composition Palmitic Stearic

*Fatty acid contribution 10.5 5.56

3

Oleic

49.39

4

Linoleic

20.37

5

Linolenic

3.66

6 7 8

Arachidic Lignoceric Behenic

1.36 1.53 5.82

Chemical name Hexadecanoic Octadecanoic Cis-9 Octadecanoic Cis-9,cis-12 Octadecanoic Cis-9,cis12,cis-15 Octadecanoic Etcosanoic Tetracosanoic Docosanoic

No. of bonds -------

16:0 18:0

Saturated /Unsaturated Saturated Saturated

Chemical formula C16H32O2 C18H36O2

Mol. weight 256 284

Single

18:1

Unsaturated

C18H34O2

282

Double

18:2

Unsaturated

C18H32O2

280

Triple

18:3

Unsaturated

C18H30O2

278

-------------

20:0 24:0 22:0

Saturated Unsaturated Unsaturated

C20H40O2 C24H48O2 C22H44O2

312 368 340

Structure

indicates the Honge oil was tested at Banglore Test House. Banglore, Karanataka, India.

The fatty acids release energy when they are combusted in combustion chamber of internal combustion engine. In the process of transesterification, the fatty acids are separated from the glycerol. Thereby fatty acids are produced which are then bonded to type of alcohol used. Different types of oils contain different types of fatty acid chains. Therefore this feature results in changes in properties of oil. Some of the researchers suggested that, the higher oxygen content of vegetable oil leads to complete combustion [47, 48, 49, 50]. But, the oxygen content in vegetable oil reduces the energy content of vegetable oil and biodiesel. The carbon chain length and double bonds affect the chemical behavior of oils during combustion. There are many types of fatty acid chains available from different vegetable oils. Therefore the chemical properties differ from oil to oil. The degree of unsaturation depends on number of double bonds [45]. In Honge oil, oleate, Linoleate and linolenate fatty acids are said to be unsaturated and palmitic and stearate fatty acids are saturated. Saturated methyl esters possess favorable features like higher cetane number and heating value compared to their unsaturated counterparts, but it also has a higher viscosity and pour point, which is not desirable during engine operations under cold climatic conditions. The vegetable oil is made up of many types of fatty acids, which are shown in the Table 1 with their chemical structure. The fatty acids contribution, chemical formula, structure [3, 30, 33, 48] and their molecular weight are tabulated in the Table 1. The ignition delay is affected

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

230

N. R. Banapurmath, V. S. Yaliwal, R. S. Hosmath et al.

by molecular structure of fatty acids present in the oil. Longer fatty acid chain length, higher saturation and an increase in the chain length of alcohol moiety decrease the ignition delay [18].

4.3. Fuel Processing In this section the fuel processing method for Honge and sunflower oils are only presented. Figure 2 and 3 shows the variation of conversion obtained with pressure reactor method with pressure and reaction time. It is clear that, the conversion of vegetable oil to biodiesel is proportional to time and pressure. The amount of methyl and ethyl esters (biodiesel) produced is mainly dependent on reaction rate and it increases with increase in pressure and temperature. The increase in reaction rate with increase in pressure and reaction temperature varies with a time [4]. The honge oil methyl ester (HOME) and Sunflower oil methyl ester (SOME) obtained were 96% and 92% respectively. It is observed that, within 5 min, no conversion was observed.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

4.3.1. Fuel Properties The properties of respective esters of all vegetable oils used in the study were determined in the laboratory and are shown in Table 2 and 3. The reason for the conversion of raw vegetable oil to methyl esters is to reduce viscosity and density and to improve the cold flow properties of Honge oil (vegetable oil) and its biodiesels [51]. The properties of all the biodiesels were found to be closer to diesel fuel. These properties include viscosity, density, cloud and pour points, flash point, calorific value. 4.3.2. Viscosity Viscosity is defined as the resistance to flow. Vegetable oils have significantly higher viscosity at normal temperature. This feature makes the oil difficult during extraction and injection [52]. The kinematic viscosity of all the oils was determined by Redwood viscometer. The indication of high viscosity affects the fluidity of the oil and it leads to poor atomization [53] leading to poor combustion. To reduce the high viscosity of raw oil, different method were proposed and developed. From Table 2 the viscosity of all the biodiesels was comparable diesel fuel. Table 2. Properties of Edible oil Biodiesels [Omer et al, Saravananan et al, Vicente et al. Properties Kinematic Viscosity @40 0 C Flash point 0 C CV kJ/kg Density kg/m3 CN Cloud point 0 C Pour point 0C Acid value

Sunflower oil 4.9

Rice Bran Oil 4.1

Palm Oil 4.4

Coconut oil 3.5

170 45300 0.8 48 1.0 -4 0.24

169 39436 0.889 53.3 -----0.48

36600 0.87 69.5 --------

41000 0.877 49

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Production of Renewable Liquid Fuels Using Different Fuel Processing Methods

231

Table 3. Properties of Non-edible oil Biodiesels [Soo- Young- No, Banapurmath et al] Properties Kinematic Viscosity @40 deg. C Flash point deg C CV MJ/kg Density kg/m3 CN Cloud point Deg C Pour point Deg C Acid value

Honge oil 3.8-9.6

Jatropha oil 3.0- 5.65

Neem Oil 3.2- 10.7

Mahua Oil 2.7 – 6.2

175 37.2 – 43.0 865- 898 36-61 -2 to 24 -6 to 14 ---

170 37.2 -43 862-886 43-59 4-10 2-6

185 39.6-40.2 820 – 942 51-53 -

165 36.8 – 43.0 828- 865 47-51 3 to 5 1 to 6

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

4.3.3. Cetane Number The cetane number is an indication of fuel quality. Comparatively, the cetane numbers of biodiesels are higher than neat diesel fuel. From the literatures, it is observed that the cetane number of vegetable oils varies from 48 – 54. This is due presence of longer fatty acid carbon chains and more saturated hydrocarbons in a renewable liquid fuels (raw vegetable oils and biodiesels) [42]. This higher cetane number of vegetable oil reduces the ignition delay during combustion. As the timing is retarded, a decreasingly smaller amount of combustion may take place during pre-mixed combustion and a corresponding increase in diffusion phase occurs [19]. 4.3.4. Density The density of biodiesels was found to be higher than neat diesel fuel. This may be due to presence of triglycerides in oil. The density of biodiesels can also be reduced by blending them with diesel fuel and/or ethanol. By adding 20% ethanol on volumetric ratio, reduce specific gravity by about 1.6% compared to neat biodiesels [53]. Park et al (53) developed empirical relation for determining the density of fuel. Demirbas [52] reported the relationships between density and viscosity of vegetable oils. Table 4. Comparison of Biodiesel quality with conventional and MACTM method Sl No

Properties

1

Viscosity @ 40 0 C (cst) Flash point 0 C Calorific Value in Kj / kg Specific gravity Density Kg / m3 Percentage of Yield Type of oil

2 3 4 5 6 8

POME

HOME

JOME

Conve ntional 5.7

Micro wave 5.8

Conve ntional 5.6

Micro wave 5.8

Conve ntional 5.65

Micro wave 5.8

164 33500

166 ----

163 36,010

167 ----

170 38,500

176 -----

0.880 0.89 880 890 96% 94% Edible oil

0.870 0.89 890 890 98% 95% Non edible

0.87 0.880 870 880 96% 94% Non edible

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

232

N. R. Banapurmath, V. S. Yaliwal, R. S. Hosmath et al.

4.3.5. Flash Point Flash point is the lowest temperature, at which its vapors are produced to ignite into a flame. The flash points of biodiesels tested were found to be higher than neat diesel fuel. Thus, these can be used as a fuel without any fire accidents. The flash point of the oils is reported in Table 2.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

4.3.6. Calorifc Value The power developed by the engine largely depends on the heat energy released by combustion of a fuel used. This property decides the ability of a fuel to be used in an engine [54]. Higher the calorific value, higher heat released for a known quantity of fuel burnt under specific conditions. The calorific value of vegetable oil is lower than diesel fuel. This is because of presence of moisture (oxygen) in a vegetable oil. It was found to be approximately 10 -11 % lesser than diesel fuel. This calorific value is closely related to the performance of an engine. The calorific value of different fuels tested is shown in Table 2. 4.3.7. Cloud Point and Pour Point The cold-weather characteristics of liquid fuels are measured by the cloud point (CP) and the pour point (PP). The cloud point is the temperature of the fuel at which solid crystals are produced when fuel attains some particular low temperature and pour point is the minimum temperature of a fuel, at which the liquid ceases to flow. The presence of saturated fatty acids in oil increases the cloud and pour point. The length of the fatty acid chain influences on the viscosity and crystallization temperature. The degree of unsaturation affects both viscosity and crystallization temperature. The cloud point of biodiesel can be reduced by using a branched-chain alcohol instead of methanol during processing [55]. The cold flow properties can also be improved by using additives and biodiesel blending with another lower cloud point biodiesel. The fatty acid length chain affects the viscosity and crystallization temperature, but branching affect only the crystallization temperature to a significant extent. Joshi et.al [14] developed the empirical equations to predict both cloud and pour points of biodiesels and their blends with diesel fuel. The cloud point and pour point of fuels tested are shown in Table 2.

CONCLUSIONS Following conclusions are made from the present study. 1.Vegetable oils has significantly has higher viscosity at normal temperature and also has slight compressibility, than edible vegetable oils. This feature makes the oil difficult during extraction and injection. 2.Saturated components of oil possess favorable features like higher cetane number and heating value compared to their unsaturated counterparts, but it also has a higher viscosity and pour point. 3.Presence of oxygen in both edible and non-edible vegetable oils reduces calorific value. 4.Use of non-edible oils for energy applications avoids the conflict between food and fuel security.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Production of Renewable Liquid Fuels Using Different Fuel Processing Methods

233

5.The number of double bonds present in the fatty acids is strongly related to emissions. The difference in the physico-chemical properties greatly affects the performance and emission characteristics of diesel engine. 6.Vegetable oils usually have Palmitic and stearic saturated fatty acids. They are the responsible for higher cetane number. Biodiesel production from Conventional Transesterification Method: 1.This conventional transesterification method is suitable only to produce a biodiesel on a large scale base. 2.Biodiesel production from pressure reactor was found to be simple, low cost and economical. But this method takes more time (1- 3 hours). 3.This method requires a vegetable oil which must have no moisture and lower acid value. 4.The conversion obtained for Honge and sunflower oils are 96 and 98%. Biodiesel production from pressure Reactor Method:

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

1.Biodiesel production from pressure reactor was found to be simple, low cost and economical. Methyl esters can be produced within short time. Maximum up to 92 % to 96% (HOME) yield can be obtained compared 98% yield from conventional transesterification process. The carbon chain length and double bonds affect the chemical behavior of oils during combustion. 2.After transesterification, the kinematic viscosity of HOME and SOME reduced to 2.336 and 2.56 times than that of raw Honge and sunflower oil respectively and the density was also reduced to 880 and 870 kg/m3 compared to 927 and 915 kg/m3 for raw Honge and sunflower oil. Biodiesel production from Continuous Microwave Transesterification Method: 1.The quantity of catalyst and methyl alcohol used is crucial for successful reaction. Washing is necessary to drain away undesired contaminants in the biodiesel. The biodiesel should be finally heated to remove excess moisture. 2.The optimum values of the parameters that result in highest biodiesel yield of HOME and SOME are 96% and 98% are 1% NaOH catalyst, 5:1 molar ratio of methyl alcohol, 60 minutes and 65 oC respectively. 3.In Microwave assisted Transesterification Method system, the experimental results have shown rapid reaction rate and higher conversion yield of trans-methylation oils to biodiesel. 4.The complete reaction had been occurred under the MAT (microwave assisted transesterification) system. 5.For sunflower oil the reaction time was reduced to 60 seconds as against 1 hour in conventional method. 6.For Non-edible oils of Honge and Jatropha the time taken will vary between 5 to 10 Minutes as compared to 1-3 hours of Conventional method.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

234

N. R. Banapurmath, V. S. Yaliwal, R. S. Hosmath et al.

7.All the biodiesel obtained from MATP resulted in slightly reduced performance due to their comparatively higher viscosity. Also the smoke opacity, HC and CO emissions increased with such oils.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

REFERENCES [196] http://www.niir.org/projects/projects/renewable-energy-non-conventional-energy-solarenergy- biofuel- b iomass/z,, 52,0,64/index.html. [197] Sukumar Puhan, N. saravanan, G. Nagarajan, N. Vedaraman, ―Effect of Biodiesel Unsaturated Fatty Acid on Combustion Characteristics of a DI Compression Ignition Engine‖, Biomass and Bioenergy, 34, 2010, 1079 – 1088. [198] Murugesan. A.; Umarani C.; Subramanian R.; Nedunchezhian N.; (2009): ―Bio-diesel as an alternative fuel for diesel engines— A Review‖. Renewable and Sustainable Energy Reviews, Volume 13, Issue 3, 653-662. [199] V. S. Yaliwal, S.R. Daboji, N.R. Banapurmath, P.G. Tewari, ―Production and Utilization of Renewable Liquid Fuel in a Single Cylinder Four Stroke Direct Injection Compression Ignition Engine‖, International Journal of Engineering Science and Technology, Vol. 2 (10) 2010, 5088- 5099. [200] Rajput R.K., ―Thermal Engineering‖, Laxmi Publications, New Delhi, India edition 2006, 1567 – 1596. [201] Pramanik, K., 2003. Properties and use of jatropha curcas oil and diesel fuel blends in compression ignition engine. Renewable Energy, 28, 239–248. [202] Vellguth, G., 1983. Performance of vegetable oils and their monoesters as fuels for diesel engines. Society of Automotive Engineers. Paper No. 831358, [203] Srivastava,A. and Prasad,R., 2000. Triglycerides-based diesel fuels. Renewable and Sustainable Energy Reviews, 4, 111–33. [204] K.Yamane, A.Ueta, Y.Shimamoto. ―Influence of physical and chemical properties of biodiesel fuels on injection, combustion and exhaust emission chariectersties in a direct injection compression ignition engine.‖ International Journal of engine research. 2, No4 IMech E, JER 02801, 2001, 249-262. [205] S Ramadhas, S.Jayaraj, C. Muraleedharan , "Use of Vegetable Oils as I.C engine Fuels : A Review", Renewable Energy, 29, 2004, 727-742. [206] B.K. Barnwal, M.P. Sharma , "Prospects of biodiesel production from vegetable oils India," Renewable and Sustainable Energy Reviews, Vol. 9 ,2005, 363-378. [207] D. Agarwal, L. Kumar, A.K. Agarwal, "Performance Evaluation of a Vegetable oil fuelled CI Engine". Renewable Energy, 2007. [208] R. Sarin, M. Sharma, " Jatropha Palm biodiesel blends: An optimum mix for Asia", FUEL, Vol. 86, 2007, 1365-71. [209] Rushang M. Joshi, Michel J. Pegg, ―Flow Properties of Biodiesel Fuel Blends at Low Temperature‖, Fuel, 86, 2007, 143 – 151. [210] Hosmani K. M., Hiremath V.B., Keri R.S., ―Renewable Energy Sources from Michelia Champaca and Garcinia Indica Seed Oil – A Rich Source of Oil‖, Biomass and Bioenergy, Volume 22, 2009, 267- 270.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Production of Renewable Liquid Fuels Using Different Fuel Processing Methods

235

[211] Srivastava A, Prasad R., ―Triglycerides-Based Diesel Fuels‖, Renewable and Sustainable Energy Reviews, 4, 2000, 111–33. [212] Vellguth G.,‖Performance of Vegetable Oils and Their Monoesters as Fuels for Diesel Engines‖.. SAE paper no. 831358, 1983. [213] Alessandro Schondorn; Nicos Ladommato S.; Jogn Willians; Robert Allan; John Reogerson (2009): The Influence of Moleculer Structure of Fatty acid Monoalkyl Esters on Diesel Combustion, Combustion and Flame, Volume 157157, 1396 – 1412. [214] N.R. Banapurmath, P.G. Tewari, R.S. Hosmath, ―Performance and Emission Characteristics of a DI Compression Ignition Engine Operated on Honge, Jatropha and Sesame Oil Methyl Esters‖, Renewable Energy, 33, 2008, 1982–1988. [215] Y.C. Sharma, B. Singh, S.N. Upadhyay. ‖Advancements in development and characterization of biodiesel: A review‖. Journal of Fuel, Volume 87, Issue 12, 2008, 2355-2373. [216] A.Demirbas, ―Biodiesel Production from Vegetable Oils via Catalytic and NonCatalytic Supercritical Methanol Transesterification Methods‖, Journal of Prog. Energy Combustion Science, 31, 2005, 46–487. [217] A.A. Refaat, ―Different Techniques for the Production of Biodiesel from Waste Vegetable Oil‖, International Journal of Environmental Science and technology, 7 (1), 183 – 213. [218] S. Carmen, M. Vinatoru, Y. Maeda, ―Aspects of Ultrasonically Assisted Transesterification of Various Vegetable Oils with Methanol. Ultrasonic Sonochemistry, 14, 2007, 2010 380–386. [219] Nwafor OMI., ―The Effect of Elevated Fuel Inlet Temperature on Performance of Diesel Engine Running on Neat Vegetable Oil at Constant Speed Conditions‖, Renewable Energy, 28, 2003, 171–81. [220] N. J., Barsic, A. C. Humke, ―Performance and Emission Characteristics of a Naturally Aspirated Diesel Engine with Vegetable Oil Fuels‖, Paper no.810262, 95-109. USA: Society of Automotive Engineers; 1981. [221] Xuezheng Liang, Shan Gao, Jiangao Yang, Mingyuan He, ―Highly Efficient Procedure for the Transesterification of Vegetable Oil‖, Renewable Energy, 2009, 1 - 3. [222] Wen-Hsin Wu, Thomas A Foglia, William N Marmer, Robert O Durm Carroll E Goering, Thomas E Briggs. ―Low temperature property and engine performance Evalution of ethyl and Isopropyl esters of Tallow and Greease.‖ Journal of American oil chem. Soc. 1.75, No. 9 1998, 1173-1178. [223] Young choel bak, Joo-Hong choi, sung-bae kim and Dong-weon kang, "production of biodiesel fuels by transesterification of rice bran oil". Korean Journal of chemical engg.13(3), 242-245; 1996. [224] Vivek and A K Gupth "Biodiesel from karanjo oil", Journal of scientific and industrial research 63, 2004 39-47, [225] L C Meher ,S N Naik and L M Das "Methorolysis of pangamia pinnata(karanjo) oil for production of biodiesel "Journal of scientific and industrial research , 63, 2004 913918. [226] Laureano Canoira 1, Raman Alcantara 2, Susana Torcal 3, Nikolaos Tsiouvaras 4, Evripidis Lots 5, Dimitrios M.Korres 6. Nitration of biodiesel of waste oil; Nitrated biodiesel as a cetane number enhancer. fuel 86 (2007), 965-971.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

236

N. R. Banapurmath, V. S. Yaliwal, R. S. Hosmath et al.

[227] Ertan Alptekin, Mustafa Canakei. ―Characterization of the key fuel properties of methyl ester- diesel fuel blends. Fuel (2008) 1-6. [228] T. Eevera, K. Rajendran, S. Saradha. ‖Biodiesel production process optimization and characterization to assess the suitability of the product for varied environmental conditions‖. Renewable Energy 34 (2009) 762–765. [229] Hideki Fukuda, Akhiko Kondo. Hideo Noda, "Biodiesel fuel production by transesterification process". Journal of biosience and Bioengineering vol. 92, No 57 405-416, 2001. [230] Ayhan Demirbas, ―Production of biodiesel fuels from linseed oil using methanol and ethanol in non-catalytic SCF conditions‖, Biomass and Bioenergy, Volume 33, Issue 1, January 2009, 113-118. [231] Zlatica J. Predojević. ―The production of biodiesel from waste frying oils: A comparison of different purification steps‖. Fuel, Volume 87, Issues 17-18, December 2008, 3522-3528. [232] Zlatica J. Predojević. The production of biodiesel from waste frying oils: A comparison of different purification steps‖. Fuel, Volume 87, Issues 17-18, December 2008, 35223528. [233] Xin Deng, Zhen Fang, Yun-hu Liu, Ultrasonic transesterification of Jatropha curcas L. oil to biodiesel by a two-step process. Energy Conversion and Management Volume 51, Issue 12, December 2010, Pages 2802-2807. [234] Yun Liu, Hong-ling Xin, Yun-jun Yan. Physicochemical properties of stillingia oil: Feasibility for biodiesel production by enzyme transesterification‖. Journal of Industrial Crops and Products, Volume 30, Issue 3, November 2009, Pages 431-436. [235] P. Selva Ilavarasi, G. laxmi narayanrao, P.V.R. Iyer, K. Ravichandran, N. Rajendran, ―Biodiesel from high FFA saturated Non-edible Oil by using Multi –Step Transesterification Process‖, International Conference on Renewable Energy and Environment for Sustainable development. IIT New Delhi, 11-13. 12. 2008, 763 – 771. [236] Zlatica J. Predojević. ―The production of biodiesel from waste frying oils: A comparison of different purification steps‖, Fuel, Vol. 87, Issues 17-18, 2008, Pages 3522-3528 [42] A. Srivastava, R. Prasad, ―Triglycerides-based diesel fuels‖, Renewable and Sustainable Energy Reviews, 4, 2000, 111–133. [237] Ahn E, Koncar M, Mittelbach M, Man R. ―A low-waste process for the production of biodiesel. Separation‖, Science and Technology, 30, 1995, 2021–33. [238] Nezihe Azcan, Aysegul Danisman, ―Microwave assisted transesterification of rapeseed oil‖, Fuel, Volume 87, Issues 10-11, August 2008, 1781-1788. [239] Y.C. Sharma, B. Singh, S.N. Upadhyay. ‖Advancements in development and characterization of biodiesel: A review‖. Journal of Fuel, Volume 87, Issue 12, 2008, 2355-2373. [240] Naoko Ellis, Feng Guan, Tim chen, Conrad poon, ―Ministering biodiesel production (transesterifcation) using in situ viscometer‖. Journal of chemical engineering, 128, 2008, 2000-2006. [241] Narayan reddy. J. Ramesh, A. ―Parametric Studies for Improving the Performance of Jatropha oil Fuelled CI Engine‖, Renewable Energy, 2005, 1- 23.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Production of Renewable Liquid Fuels Using Different Fuel Processing Methods

237

[242] P.K. Sahoo, L.M. Das, M.K.G. Babu. P. Arora, V.P. Singh. N.R. Kumar, T.S. Varyani, ―Comparative Evaluation of Performance and Emission Characteristics of Jatropha, Karanja and Polanga Based Biodiesel as Fuel in a Tractor Engine‖, Fuel, Volume 88, Issue 9, 2009, 1698-170. [243] Md. Nurun Nabi, Md. Mustafizur Rahman, Md. Shamim Akhter, ―Biodiesel from cotton seed oil and its effect on engine performance and exhaust emissions‖. Applied Thermal Engineering, Volume 29, Issues 11-12, 2009, 2265-2270. [244] Avinashkumar Agarwal, K. Rajamanoharan. ―Experimental investigations of performance and emissions of Karanjaoil and its blends in a single cylinder agricultural diesel engine‖, Applied Energy, Volume 86, 2009, Pages 106-112, [245] Pramod S Mehta, K. Ananda, ―Biodiesel for Engines‖. Proc. of the 21st National Conference on IC Engines and Combustion, BIT Davangere, December 10-12, 2009, 43-62. [246] A.H. Scragg, j. Morison, S G.W. Shales, ―The Use of a Fuel Containing Chlorlla Vulgaris in a Diesel Engine‖, Enzyme and Microbial Technology, 33, 2003, 884 – 889. [247] Park S.H., Yoon S.H., Suh H.K., Lee C. S., ― Effect of the temperature variation on properties of biodiesel and biodiesel- ethanol blend fuels‖, Oil and Gas Science and Technology- Rev.IFP, Volume 63, 2008, 737- 745. [248] Ayhan Demirbas, ―Production of Biodiesel Fuels from Linseed Oil Using Methanol and Ethanol in Non-Catalytic SCF Conditions‖, Biomass and Bioenergy, x, 2008, 1-6. [249] Volkhard Scholz, Jadir Noueira da silva, ―Prospectus and Risks of the Use of Castor Oil as a Fuel‖, Biomass and Bioenergy, 32, 2008, 95 – 100. [250] Subramani saravanan, G. Nagarajan, ―Effect of FFA of Crude Rice Bran oil on the Properties of Diesel blends‖, Journal of American Oil Chem.Society, 85, 2008, 663 666. [251] http://www.extension.org/pages/Biodiesel_Cloud_ Point_and_Cold_Weather_Issues. [252] P. Mahanta, S.C. Mishra, Y.S., Kushwash (): An Experimental Study of Pongamia Pinnata L. Oil as a Diesel Substitute, Proc. IMechE. Volume 220, Part A, Journal of Power and Energy, 2006, 803-808. [253] Omer Rasgid, Farooq Anwer, Bryan R Moser, Samia Ashraf, Production of sunflower methyl ester by optimized alkali catalysed methanolysis, Biomass and Bioenergy, 32, 2008, 1202 – 1205. [254] S. Saravananan, G. Nagarajan, G. Laxmi narayanan, Effect of FFA of Crude Rice Bran Oil on the Properties of Diesel Blends Journal of the American Oil Chemists' Society, Volume 85, Number 7, 663-666. [255] Vicente Bermuaez, Jose M Lujan, Benjamin Fla, W. Q. Linares, Comparative study of regulated and unregulated gaseous emissions during NEDC in a light-duty diesel engine fuelled with Fischer Tropsch and biodiesel fuels, Biomass and Bioenergy, Volume 35, Issue 2, February 2011, 789-798. [256] Soo – Young- No, Inedible vegetable oils and their derivatives for alternative diesel fuels in CI engines- Review, Renewable and Sustainable Energy, 15, 2011, 131- 149. [257] N.R, Banapurmath, P.G. Tewari, R.S. Hosmath Performance and emission characteristics of a DI compression ignition engine operated on Honge, Jatropha and Sesame Oil methyl esters, Renewable Energy, Volume 33, Issue 9, 2008, 1982-1988.

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved. Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

In: Liquid Fuels: Types, Properties and Production Editor: Domenic A. Carasillo

ISBN 978-1-61470-435-5 © 2012 Nova Science Publishers, Inc.

Chapter 8

ETHANOL FROM BIOMASS: APPLICATION TO THE OLIVE-PRUNING DEBRIS 1

Juan Francisco García1 and Javier García2

Biosystems Engineering Department, School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, National University of Ireland, Dublin, Ireland 2 Departamento de Química Inorgánica y Orgánica, Facultad de Ciencias Experimentales, Universidad de Jaén, Spain

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

ABSTRACT Bioethanol production from lignocellulose biomass by biochemical pathways represents a potential alternative source of fuel. This is especially important considering the ongoing energy crisis. In addition, the availability and renewability of lignocellulose biomasses represent a real advantage over fossil fuels. From an economic point of view, for energy production from lignocellulosic materials, it is necessary to consume the pentoses, employing micro-organisms capable of fermenting them to ethanol. This review intends to describe the main processes used for ethanol production from lignocellulosic biomass, from the acid hydrolysis processes used in the past to the enzymatic processes, which are more specific and allow higher hydrolysis yields under less severe conditions. Pre-treatments, which used to precede the enzymatic hydrolysis, are nowadays used as individual hydrolysis stage. The most promising microorganisms to ferment sugars to ethanol are described. Finally, we resume the current application of these techniques to one of the most abundant lignocellulose biomass: the olive-pruning debris, whose total annual production exceeds 2.4 × 1010 kg.

INTRODUCTION The olive-pruning debris, as the rest of lignocellulose wastes, constitutes a major potential source of renewable energy and of basic or high-value chemical products. Over 8 million ha of olive trees are cultivated worldwide. Traditionally, the olive-tree is cultivated in

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

240

Juan Francisco García and Javier García

Mediterranean countries (especially in Spain, Italy, Greece, Morocco and Tunisia), but in recent times it has been cultivated in regions of five continents (West Coast of the U.S.A., Mexico, Australia, Argentina, Chile, etc.). In olive-tree cultivation, pruning is a necessary biennial operation to eliminate old branches and to regenerate the tree. Given that a hectare of olive orchard (in traditional and intensive cultivation) produces an average of 3 × 103 kg of pruning debris per year [1], it can be estimated that the total annual production of this biomass exceeds 2.4 × 1010 kg. For this agricultural by-product, some technological applications have been found, the economic viability of which remains to be demonstrated. In most of the cases, the debris is left on the land to be incinerated or ploughed into the soil (after grinding). The drawbacks include atmospheric pollution, mineralization of the soil, increased risk of fires, propagation of pests, and the unnecessary production of CO2. A promising alternative could be pellet production, instead of the low lignin content of the olive-pruning debris (Table 1) compared to other olive biomass such as olive stones [2]. However, no sulphur is detected in the pruning (Table 3), which is an environmental advantage. Biomass pellets are densified biomass particles formed to cylindrical pellets for heat and power production. A recent study about an ordinary industrial pelletization from olive-pruning debris has been made by Carone et al. [3].

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Table 1. Olive-pruning debris fibre composition [1] Property Moisture, % Ash, % Lignin, % Cellulose, % Hemicellulose, %

Wood 10.7 1.5 14.7 32.8 26.9

Leaf 8.5 5.0 23.1 5.3 16.3

Total 10.2 3.3 20.8 36.6 19.7

Table 2. Elemental analysis of the olive-pruning debris [1] Element Carbon, % Hydrogen, % Nitrogen, % Sulphur, %

Wood 45.5 6.4 0.3 0.0

Leaf 48.7 7.1 1.4 0.0

Total 44.6 6.7 0.8 0.0

Another way to make use of this fraction is by hydrolysing the main components: cellulose, hemicellulose, and lignin. The hydrolysis process, acid or enzymatic, of this agricultural waste provides a sugar solution from the hemicellulose and cellulose fractions, which, by fermentation with yeasts and fungi, can generate products of industrial interest. Second generation bioethanol uses non-food crops or inedible waste products and does not divert food away from the animal or human food chain. The conversion of biomass to ethanol generally includes four steps: pre-treatment, hydrolysis of polysaccharides and oligosaccharides into monomer sugars, fermentation of sugars to ethanol and, finally, ethanol concentration to absolute alcohol. The production of fuel-ethanol from lignocellulose biomass is of growing interest around the world because it can provide a number of environmental

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Ethanol from Biomass: Application to the Olive-Pruning Debris

241

advantages over conventional fossil fuels, most notably a reduction in greenhouse-gas emissions. Fuel ethanol can be utilized as gasoline oxygenating, thus elevating its oxygen content, allowing a better oxidation of hydrocarbons and reducing the amounts of greenhouse gas emissions into the atmosphere. However, the higher production cost for bioethanol (1.3 dollars/dm3, from lignocellulosic biomass) as compared to gasoline, and its lower heating value (26700 kJ/kg at ambient temperature) are some problems of this alternative fuel [4]. Ethanol contains only about two-thirds the energy per volume of an equal amount of gasoline, but efficiently designed engines could increase the travel range of pure ethanol to about 80% that of gasoline. From the hemicellulose fraction, which can involve 15 to 35% of the waste on a dry basis, D-xylose is the main monosaccharide obtained. Its fermentation with yeasts capable of metabolising both D-xylose and D-glucose (e.g., Candida tropicalis, Pachysolen tannophilus, Hansenula polymorpha) under microaerobic conditions can produce xylitol, a valuable product for its sweetening properties and which, for not being metabolizable by insulin, makes it highly desirable for the preparation of products for diabetics. In obtaining xylitol, ethanol is generated as a by-product, and this can increase the economic viability of the bioprocess.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

LIGNOCELLUSIC BIOMASS PRETREATMENTS Lignocellulosic biomass is a complex mixture of carbohydrate polymers from plant cell walls, known as cellulose and hemicellulose, plus lignin, ash and a smaller amount of other compounds generally known as extractives. Cellulose consists of thousands of strands, each strand made up of hundreds of glucose units linked up together. The cellulose is wrapped in a sheath of hemicellulose and lignin, which protects the cellulose from being broken down. Hemicellulose is a heterogeneous class of polymers containing pentoses (D-xylose, Larabinose), hexoses (D-mannose, D-glucose, D-galactose) and uronic acids [5], which is easier to break down than cellulose into its component mixture of sugars. Hydrolysis processes are intended to recover the maximum amount of sugars from cellulose and hemicellulose fractions for subsequent fermentation. Lignin is usually not attacked, and its degradation produces phenolic compounds that could inhibit fermentation processes. In the case of operating in more severe conditions to hydrolyze the lignin, the objective is to recover these phenols for use as antimicrobial agents. To produce ethanol from biomass feedstock, a pretreatment process is used to reduce the feedstock size, break down the hemicellulose to sugars, and open up the structure of the cellulose. This facilitates the enzymatic hydrolysis and fermentation; cellulose is hydrolyzed by enzymes into D-glucose that is fermented to ethanol. The sugars from the hemicellulose (mainly D-xylose) should be also fermented to ethanol or xylitol. From an economic standpoint, it is desirable that pretreatment lead to a total hydrolysis of hemicellulose, so the pentoses can be recovered and separated from the cellulosic fraction. Among the developed pre-treatment technologies, the most promising are based on hot water or steam leading to the formation of two parallel streams: the hemicellulose-rich liquids (totally or partially hydrolyzed to oligomeric and monomeric sugars) and a solid celluloserich stream (usually converted to ethanol using simultaneous saccharification and

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

242

Juan Francisco García and Javier García

fermentation process) [5]. Hemicellulose hydrolysis depends on the operating conditions: high temperatures increase the kinetics of hemicellulose solubilization and short reaction times limit the degradation of sugars and the production of inhibitory compounds [6]. The hemicellulose fraction, once solubilized, can be separated from the pretreated material with a water extraction step. Lignin can be extracted from the insoluble fraction by an alkaline solution. The extraction of alkaline residue containing lignin can be done by oxidizing agents, such as hydrogen peroxide [7]. However, this step is not necessary to improve the enzymatic digestibility of cellulose. However, it reduces the volume of the hydrolysis reactor and the energy consumption in the stage of cellulose hydrolysis and increases the sugar concentration in the reactor [8]. Among the pretreatment applied to lignocellulosic biomass, the most widely employed are:

Ultrasonic Pre-Treatment

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Ultrasound is cyclic sound pressure with a frequency above the normal hearing range of humans (>15-20 kHz). When the ultrasound wave propagates in a medium such as a liquid, it produces cavitation and acoustic streaming. The cavitation can provide high temperature and high pressure for the modification of chemical reactions and generates powerful hydromechanical shear forces in the bulk liquid, which disintegrate nearby particles by extreme shear forces. Ultrasound can produce radicals in the order of µM/min in solution. This rate is affected by parameters such as ultrasonic amplitude and frequency, temperature, pressure and types and amounts of gases present.

Figure 1. Diagram of ethanol production from biomass using ultrasonic energy at various points in a process employing acid hydrolysis pretreatment. Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Ethanol from Biomass: Application to the Olive-Pruning Debris

243

The main benefit of streaming is mixing, which facilitates the uniform distribution of ultrasound energy, convection of the liquid and dissipation of any heating that occurs. Mass transfer effects of ultrasound can reduce reaction times in heterogeneous solid-liquid systems and the production of oxidative species by ultrasound can facilitate chemical degradation. Applied to lignocellulosic biomass, ultrasound is used to facilitate the chemical degradation of lignin and cleavage of lignin-carbohydrate linkages as well as improving mass transfer. Therefore, it is suggested that ultrasound can be an effective mechanism in the enhancement of the pretreatment of biomass. In this way, the United States Patent 7,504,245 B2 provides a method comprising applying ultrasonic energy to a biomass to alcohol production process [9]. These authors designed several biomass to alcohol processes which employ ultrasonic energy as the only means of pretreatment and in combination with a concentrated acid hydrolysis pretreatment or any conventional pretreatment, such as a hydrothermal or chemical pretreatment, followed by an enzymatic hydrolysis step or a simultaneous enzymatic hydrolysis and saccharification step.

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Steam Explosion During this process the biomass is submitted to high temperatures (180-240 ºC) by pressurized steam injection (1700-4500 kPa) for a variable time (from 10 seconds to several minutes). The pre-treatment ends with a sudden decompression of the system. High temperature steaming makes cellulose and lignin degrade. Quick release of pressure damages the tissue structure. These changes make the biomass easier to hydrolyze and ferment. Despite being a very old technique, it is an attractive method (especially using an acid catalyst) allowing high D-xylose yields. A variation of this technique is the catalyzed steam explosion. The use of sulfuric acid as catalyst leads to a total solubilization and hydrolysis of hemicellulose into monomers, with no degradation in furfural [8]. The use of an acid catalyst can reduce the processing temperature (150-200 ºC) and improves the subsequent enzymatic hydrolysis. This technique has been successfully employed in the solubilization of hemicellulose from olive tree pruning in the temperature range 190-240 °C, with or without addition of diluted sulphuric acid solutions as catalyst [10].

Autohydrolysis This technique involves heating the lignocellulosic material into pressurized water. The process is similar to that of an autoclave (batch process) and allows the complete solubilization of the hemicellulose and a significant lignin solubilisation [11,12]. The term autohydrolysis has been adopted by some authors [13] to refer to the process of solubilization of the hemicellulose in an aqueous suspension at temperatures between 165 and 225 ºC. As a result, the acetyl groups contained in the hemicellulose are released, which provides an acidic medium to carry out the hydrolysis. Autohydrolysis has been applied on the olive-pruning debris in the temperature range 150-210 °C [12,14]. Although a part of lignin is solubilized, the concentrations of phenolic compounds in hydrolysates from olive-pruning debris are very low; the highest value obtained being that of vanillin (2.1 mg/L) [12]. For this reason, autohydrolysis could be used as an individual hydrolysis stage in the recovery of sugars

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

244

Juan Francisco García and Javier García

(mainly D-glucose and D-xylose) from this lignocellulosic biomass, avoiding the need to resort to enzymatic hydrolysis. Nevertheless, a substantial part of hemicellulose is not transformed to monomers, but to oligomers [14].

Pre-Treatment in Alkaline Medium These processes have been largely developed in the paper pulp mill industry. They are usually carried out with 8-12% NaOH at 80-120 ºC for 30-60 minutes. Lignin and hemicellulose are solubilized. However, the current cost of chemical reagents such as NaOH is its main drawback.

Pre-Treatment with Dilute Acid

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

Diluted-acid pre-treatment, at temperatures of 150-220 ºC, is one of the most important pre-treatments and has been reviewed for different materials [15-17], using sulphuric acid or other acids (e.g., nitric acid, hydrochloric acid). During this thermal process, hemicellulose is depolymerised into a mixture of sugar oligomers and monomers, whereas less alteration is caused in lignin and cellulose. Removal of hemicellulose increases porosity and therefore improves the enzymatic digestibility of cellulose. Applied on the olive-pruning debris, working with temperatures from 135 ºC to 200 ºC and sulphuric acid concentration from 2.5% (w/w) to 10% (w/w), this pre-treatment solubilizes all the hemicellulose and increases the cellulose content 1.5 times more compared to the initial olive-pruning debris [14].

AFEX Pre-Treatment The AFEX (ammonia fiber expansion) pre-treatment process uses liquid ammonia to cause the breakdown of cellulose and hemicellulose, followed by a strong decompression in order to evaporate the ammonia. It can be considered a variant of the steam explosion, carried out in milder conditions, thus minimizing the production of inhibitory compounds. Residual ammonia can be used as a nutrient for the microorganism in the later stage of fermentation. For these reasons, cellulosic material pre-treated with the AFEX process doesn‘t need to be washed or detoxified, allowing ethanol to be created from cellulose without added nutrients or other steps. However, this pre-treatment is ineffective with woody substrates [18]. The use of a dangerous product like ammonia should also be noted, as a disadvantage. Carbon dioxide could be used instead of ammonia, with the benefits that it entails [8]. However, this technique has never been developed for ethanol production.

Ozonation Ozone is the strongest chemical oxidant after fluorine. At first, this technique was used to remove lignin from the lignocellulosic biomass to facilitate subsequent enzymatic degradation. The use of ozone has the following advantages:

Liquid Fuels: Types, Properties and Production : Types., Properties and Production, Nova Science Publishers, Incorporated, 2012. ProQuest Ebook

Ethanol from Biomass: Application to the Olive-Pruning Debris   

245

After ozonation there is no residue consisting of acids or mineral bases (ozone breaks down within minutes after its generation). Ozone can be generated by the ozonation plant itself avoiding the problem of transportation and storage of toxic chemicals. Ozone reactions are carried out at ambient temperature and pressure.

However, due to the high cost of ozone production and its inherent instability, which prevents delay to the period of use after production, this technique is not used as a pretreatment. Some authors [19] have assayed the ozonation to obtain phenolic compounds from lignocellulosic biomass. This possibility could be more attractive from the economic point of view.

Extrusion

Copyright © 2012. Nova Science Publishers, Incorporated. All rights reserved.

The continuous extrusion process is an attempt to develop a cost-effective pre-treatment method for enzymatic saccharification. This technique combines thermal, mechanical and chemical action. An extrusion process involving a twin-screw extruder was carried out with olive-pruning debris [20]. High cellulose and hemicellulose conversion were obtained, but sugar yield was low. At low temperature (70 ºC) and a sulphuric acid concentration (