Problems on Fundamentals of Hydraulics and Heat Engineering

Citation preview

V .G . EROKHIN, M.G.MAKHAN’KO

MIR PUBLISHERS

Problems on Fundamentals of Hydraulics and Heat Engineering

B.

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EPOXMH, M.

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MAXAHbKO

CBOPHMK 3 AAAH no OCHOBAM mAPABJlHKM H TEnJIOTEXHMKn H3flaTe^bctB0 «9Heprnfl» MocKBa

V. G. EROKHIN AND M. G. MAKHAN’KO

Problems on Fundamentals of Hydraulics and Heat Engineering Translated from Russian by NATALIA DEINEKO

Mir Publishers • Moscow

First published 1986

Revised from the 1979 Russian edition

Ha aneAuucKOM H3bine

© HaflaTejibCTBo «9HeprHH», 1979. © English translation, Mir Publishers, 1986.

Contents

Preface 1

Fundamentals of Hydraulics. Pumps

1.1 1.2 1.3 1.4

Physical Properties of Fluids Hydrostatics Hydrodynamics Pumps

7 8

8 13 24 44

2

Fundamentals of Engineering Thermodynamics

2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12

The State of a Working Fluid Mixtures of Ideal Gases Heat Capacity The First Law of Thermodynamics Basic Thermodynamic Processes The Second Law of Thermodynamics Steam Outflow and Throttling of Gases and Vapours Cycles of Steam Power Plants Internal Combustion Engines and Gas Turbine Cycles Cycles of Refrigerating Machines Moist Air

50 55 59 67 69 80 83 87 93 98 103 107

50

3

Fundamentals of Heat Transfer

111

3.1 3.2 3.3 3.4 3.5

Heat Conduction Heat Transfer by Convection Boiling and Condensation Heat Transfer Heat Transfer by Radiation Overall Heat Transfer

111 115 120 123 128

4

Compressors and Fans

133

4.1 4.2

Compressors Fans

133 141

5

Fuel and Its Combustion

143

5.1 5.2 5.3

Fuel Composition The Process of Combustion of a Fuel Furnaces (Strokers)

143 150 157

5

6

Boiler Units

158

6.1

Heat Balance and Efficiency of aBoiler Unit and Fuel Rate

158

7

Heat Utilizing Systems

166

7.1 7.2 7.3 7.4 7.5

Heat Exchangers Evaporator Systems Distillation and Rectification Systems Driers Industrial Furnaces

166 170 180 184 190

8

Heat Supply Systems

195

8.1 8.2 8.3 8.4 8.5

Central Heating Ventilation System Hot Water Supply Air Conditioning Heating Systems

195 202 207 210 216

9

Internal Combustion Engines

225

9.1 9.2

Engine Power Fuel Consumption and Efficiency ofan Internal Com­ bustion Engine Heat Balance of an Engine

225

Steam and Gas Turbines

233

9.3 10

10.1 10.2 10.3 10.4^

Characteristics of the Working Process in Turbines Utilization of Heat in Turbines Condensers for Steam Turbines Combustion Chambers of Gas Turbine Units

227 229 233 239 242 243

11

Steam Power Plants

245

11.1 11.2 11.3

Operating Conditions Indices Thermal Layout Diagrams Thermal Efficiency

245 248 259

12

Refrigerating Plants

267

12.1 Vapour-Compression RefrigeratingMachines 12.2 Absorption Refrigerating Machines 12.3 Thermocompressors Appendices

267 270 272 275

Preface

This book of problems has been compiled in accordance with the curriculum “Fundamentals of Heat Engineering and Hydraulics” for technicians of industrial and technolog­ ical specialities. Each chapter contains the basic theoretical concepts, the computational formulas and relations and some typical problems, some of which are solved. Some of the problems and appendices are taken from the literature on the subject. The appendices contain the refer­ ence data required to solve the problems. The problems mainly use International System of Units (SI). However, since many of the instruments used in indus­ try are graduated using other systems of units, these units are also used in some problems. Chapters 1, 5, 6 and 11 and sections 7.2, 7.3, 8.1, 8.2, and 8.3 were written by V.G. Erokhin, and the rest of the hook by M.G. Makhan’ko.

I. Fundamentals of Hydraulics. Pumps 1.1. Physical Properties of Fluids 1.1.1. Definitions

Basic physical properties of liquids are density, specific gravity, compressibility and viscosity. Density p, kg/m3, is the mass of a homogeneous fluid con­ tained in a unit volume: m P= y i

/ a a\ (1-1)

where m is the mass of liquid, kg, and V is its volume, m3. Specific gravity y of a fluid, N/m3, is the weight per unit volume of the fluid: V= 4 ->

(!.2)

where G is the weight of the fluid (the force of attraction by the Earth), N, and V is the volume, m3. Density and specific gravity are connected through the relation V = P£. (1-3) where g is the acceleration due to gravity, m/s2. The density and specific gravity of a liquid vary with pres­ sure and temperature. Compressibility is the property of liquid to change its vol­ ume with pressure. Compressibility is characterized by the isothermal volume compressibility %, m2/N: X =

V0 Ap

’

where V0 is the initial volume, m3, AF is the change in vol­ ume, m3, and Ap is the change in pressure, Pa. The quantity reciprocal to isothermal volume compres­ sibility is called tfie modulus of elasticity E of a liquid. The 3

modulus of elasticity for water under normal conditions can be assumed to be equal to E = 2.0 X 109 Pa. An increase in the volume of fluid being heated is char­ acterized by the coefficient of thermal expansion 1/°C: AT*

C\

70Af Viscosity is the property of a fluid by virtue of which it offers a resistance to flow (shear) of its particles. Viscosity of a fluid is characterized by kinematic viscosity v, m2/s, and dynamic viscosity p, N-s/m2, which are con­ nected through the following relation: V=

(1.6)

The temperature dependence of the kinematic viscosity of water is determined by the following formula: v = ---------

00178--------------

(l+0.0337< + 0.000221