Thermodynamics & Heat Engines

746 Pages·2001·176.146 MB·English

by  R. Yadav

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RY.A DAV
CENTRPAULB LISHHOIUNSGE
ALLAHABAD
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Themrodyna&m HiecasEt n gines
VolumIe
(THERMODYNAMICS)
(SI Units)
R. YADAV
B.SEcn.g Mg..E,P. h,. FD..l,. E.
Profe&s FsoorrmH eera d
MechanEincgailn eDeerpianrgt ment,
M.N.ERn.g ineCeorlilnegg e
Allahab0a0d4- 2n
AND
SANJABY.M,E. ,E .
SrE.n ginTeAeTrAP, r o·jLe1rcDtH.y,d erabad
AND
RAJAY,
l:S.Tech.
EnginBe.eHr.,HE a.rLd.w,a r
•
Central Publishing House
18-SCa,r ojNianiidMu a rg,
.A llahabGa0d1•211
© COPYRIGHT 1991
Publisher and Author
First Edition 197 5
Second Edition· 1981
Revise.d Edition 1985
.·
Fourth Edition (Sli 1986
� Fifth Revised Edition 1988
Reprinted : 1991
Reprinted 1994
Sixth. ReviseJ Editicn 1997
. Seventh Revised Editio� lOOO · • 2001
Reprint 2002 -. 2003
ISBN 81-854,44-02-1
. . .
Printed in India ai the Halcyon .Press, 18-C, Sarojin i Naidu Marg. Allahabad .
.and Published by Central 'Publishing House, 18-C. Sarojini Naidu Marg. Allah,1h.i
• I • ' •
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CAIL-- g
P:REFA'I'COES IXTRHE VIS(ESEDID )I TION
Updating and change are the essence ofa popular text book. Keeping this in 'view the
present edition is an attempt in this direction. In this edition a thorough revision has been
made. Some new articles have been added. All figures have been replaced by new ones with
more informations and larger in size .. Some more typical high standard numericals have been
solved and also added in excercise section. The book has been presented in royal size. I hope
_ that this new edition will prove more meaningful and useful to students.
Allahabad
Engineers Day, 1997
R. Yadav
Sanjay
Rajay
PRE-FATCOET HES IE DITION
Most of the engineering institutions in India and abroad have switched over from MKS
or FPS to SI (Systeme Internationale) System of Units' and rest are in transition iaage. In
view of this, this book has been thoroughly revised in SI units to cater to the need·s of stude·n t
community and to keep pace with-the new developments.
Chapters 7 and 9 have been renamed according to their CQntents. Chapters Io; 11, 12
and 13 have been thoroughly revised.
In the preparation of this edition, the author has consulted a large pumber of books
which are listed in the References. The author sincerely acknowledges them. Any mistakes
and error found i,IYlhe tes� will be appreciated if it is brought to the notice of the author.
Finally. the author wishes to thank his wife Meera and sons Sanjay and Rajay who
endured cenam hardness due to his engagement in completing this work.
19th June. 1986
Alhthabad
R. Yadav
•
PREFATCOET HEF IRSETD ITION
This book has been written to suit the courses followed in engineering colleges,
A.M.I.E., U.P.S.E., U.P.P.S.C. and other similar institutions. As there is no book available
in the market that covers the full syllabus the present attempt is expected to fill this gap.
Because of the compass to this book involves the subject has been divided into two parts,
of which volume I covers the syllabus of 'Thermodynamics' while volume II covers the
syllabus of 'Heat Engines'.
I have attempted in this book to present the matter in a simple lucid and precise manner
keeping in view the student's difficulty in solving problems and hints have been given where
they are likely to go wrong. A novel feature of this book is that a large num�er·of problems
have heen taken from most of the leading universities of India and abroad, U.P.S.C. and
U.P.P.S.C. and solved. I have also taken the liberty of adding, at the end of each chapter a
number of viva voce, theoretical and numercial questions wih answers. It is hoped that they
will add to the usefullnessiOf the book for the students for whom it is primarly meant.
I take this opportunity to express my gratitude to Or. B.K. Gupta, Professor and Head,
Mec.:h. Engg. Deptt. M.N.R. Engg. College, Allaryabad; Sri. P.N. lv1askara, Reader in mech.
Engg. Deptr., M.N.R. Engg. College, Allahabad to my colleagues and well wishers for their
encouragement.
. .
I am indebted to the various authors whose books I have consulted in the preparation
ot this book. ·
And last but not the least, credit goes to my wife Meera without whose co-operation
I could not even think of going for this venture.
And lastly, I would appreciate suggestions and criticism of the views expressed in this
book with a view to its improvement.
IIT Delhi R. Yadav
.lune 9th, 1975
. �'
CONTENTS
l. BASIC CONCEPTS AND DEFINITIONS : Thermodynamics; Dimensions and
units; Mass and weight; Thermodynamics system; surrounding and universe; Types and
system; Macroscopic and microscopic point of view; Concept of continuum; Density and
specific weight; Specific volume; Specific Gravity; Pressure; Thermodynamic equilibrium;
Property; State; Path; Process; Cyclic Process; Quasi- static 'process; Reversible Process;
Irreversible process; Energy; Work; Power; Forms of .works during Quasi-static process;
Nonquasi static Foi:ms of works; Work as a path Function; Heat; Singn corivenfion of various
energies in their algebric sense; Mechanical Equivalent of Heat. 1-45
.
(yTEMPERATU RE AND ZEROTH LAW OF THERMODYNAMICS : Concept of
temperatur�; Equality of temperature; Zeroth Law of Thermodynamics; Measurement of
temperature; Temperature scale; Liquid thermometers (Mercury); Limitations of liquid
Thermometers; Gas.._ thermomet, ers; Principles of gas thermometers; Constant volume gas
thrmometer; Electrical resistance Thermometers; Thermoelectric thermo�ek:rs; Radiation
Pyrometer; Segar Cone; Optical pyrometer; The International temperature scale; Practical
· · ·
aspect of temperature measurement. 46-65
®
iDEAL (PERFECT) AND REAL GASES : Concept of an ideal Gas
(Macro-analysis); Boyles law;• Charles' Law; Characteristic E uation of gas; Avagadro's
hypothesis (Universal gas constant); Enthalpy of an ideal gas; Specific heats o an ideal Gas;
Kinetic theory of gases (Microscopic analysis of perfect gas); Mean free path; Deviation of
rea! gases from ideal gases; Critg state; Equation of state; Vander Waal' s equation of state;·
Limitations ofVander Waal's equation; Reduced coordinates; Compressibility of factor and
law of corresponding states; Other equations of state for real gases P.V.T. surface; P.V.T.
surface of an.ideal gas; Representation of partial de:-ivatives on a P.V.T. surface. 79-155
·@IRST LAW OF THERMODYNAMICS : First law of thermodynamics; Internal
energy; Internal energy of a perfect gas; Application of First law to a closed system (Non-flow •
processes); Flow processes and control volume; Flow energy or flow work: Energy
accompanying mass in flow process; Steady and unsteady flow processes; First law of
thermodynamics applied to 9pen system; Mechanical work in a steady flow system; Steady
flow process for an id� Continuity equation; Euler and.bernoullie equations; Throttling.
process; Application of steady flow energy equations; Unsteady flow process; Filling l
:,rocess; Emptying process. I 26-212
/sECOND LAW OF THERMODYNAMICS : Limitations of First Law and essence
of Second Law; Thermal reservoir; Heat engines; Thermal efficiency of heat engines; Heat
pump and its efficiency; Available and unavailable Energy; The dead state; Statement of
Second Law; Kelvin and Clausius statement; Reasons of irreversibility Carnot cycle;
Corollary I : Maximum reversible engine efficiency (Carnot's theorem); Corollary 2: All
reversible engines have same efficiency (Carnot's theorem); Corollary 3: Thermodynaic
temperature, Absolute temperature scale or Kelvin temperature scale; Corollary 3:
JJnattainubility of negative absolute temper,llurc; Corollary 3: Unattainability of asolute zero
temperature; Corollary 4: Clausius inequality; Corollary 5: Entropy; Corollary 6:
Temperature entropy diagram; Entropy changes for an ideal gas during proc.,esses: Carnot
cycle on T.S. diagram; Physical interpretation of entropy. Causes of irreversi�ility. 2 I 3-298 /
6. GENERAL THERMODYNAMIC RELATIONS AND THIRD LAW :
Introduction; Some mathematical preliminaries; definitions; Differential relations for
U.H.G. and F; Some important properties expressed in differential form; Generalised
relations for Cp Cv Kand �; Relations for internal energy and enthalpy; The various T.ds
-equations; clapeyron equation; Gas tables; Third law of thermodynamics. 299-323
/.A VAILABILITY. IRREVER_SIBILITY AND "EQUILIBRIUM, Introduction;
Availability of heat; Availability of a clpsed system; Availability function of the closed
system; Av.ailability of steady flow system; availability function of open system; -
irreversibility for closed open system; Effectiveness; Second La� analysis of the power
plant; CJ1emical potential; Criteria of equilibrium; Types of equilibrium. 324-358
�
OPERTIES OF PURE SUBS�A NCE : Pure substance (steam); Phase�; Phase
Transformation (Formation of steam) at constant pressure; Saturation pressure and
temperature of steam: Enthalpy changes during formation of steam; West steam (two phase
Mistures); Properties of steam; Steam property diagrams; Processes of vapor (steam);
Constant pressure processes; Adiabatic process (reversible and irreversible); Isothermal
process; Polytropic process; Throttling process; method for determining the dryness
fractions; Super critical pressure of steam; Super saturated flow of steam. 359-432
9. NON-REACTIVE GAS MIXTURES AND PSYCHROMETRY : Introduction,
Some basic definitions for gas gixtures; P.V.T. relationship for mixtures of ideal gases;
Properties of mixtures of ideal gases; Entropy changes due to mixing; Mixtures of perfect
Gases at different initial pressures and temperatures; Hetrogeneous system of several phase�;
Mixture of gas and vapours; Psychometric terms; West bulb temperature; Adiabatic
saturation temperature; Enthalpy of moist air; Psychrometric chart; Psychrometric process;
Adiabatic mixing of Air streams; Sensible heating and cooling process; By pass factor :
Humidification and dehumidification processes; Cooling and humidification; Heating and
f
humidiication : Heating and dehumidification : Cooling and dehumidification process;
Summary of psychometric processes; application of psychometrics. 433-500
, �AS POWER CYCLES : Introduction; Air standard cycles; Some definitions for
pist�nder arrangement; Carnot cycles; Otto cycle; Diesel cycle; Dual cycle;
Comparison between Otto, Diesel and dual cycle; Variatipns between the Air standard Otto
cycles and actual cycles; Effect of variable specific. heat and dissociation on air standard
Otto Cycle; Variation between the air cycles and the actual cycle of diesel engines.
501-574
11. VAPOR POWER CYCLES : ln_troduction; The Carnot vapour cycle; Rankine
cycle; Effects of operating condition on efficiency; Principle of increasing the thermal
efficiency; Method of increasing the thermal efficiency; Deviation of actual cycle fr.om
theoretical cycle; Thermal efficiency ratio and S.S.C.; R�uirement of an ideal working
FluRiedg;e nefreaehtdei avteci yncglT ehsre;e hceyact� Binarcyy-cvNlauepc;ol re ar
powpelra cnytc lSeosle;an re ry-pploaGwneetor.t haenrmOdaT lE pCo wpelra nts.
575-639
12D.I REECNTE RGCYO NVERS:II OnNt rodTuhcetrimoone;cl oencvterritce rs:
Thermicoonnivce Mrtaegrnse;t ohydgreodnyenraamtio)crS; (o Mlc.aepDrlo. lwH pe.lr a nts;
Fuecle lFlusec;le slyls tuenmdd eerv eloHpymdernotg;e nf-uoecxelyl gDleisnr; e cto
oxidahtyidornoc afrubceoelnl I lnsd;io rxeicdtaf tucieeolln l s. 640-667
13F.U ELASN DC OMBUSTI:IO nNt rodCulcatsisoinof;fiF cuaetMliosol;ne .
KilogarnMadom l Fer acCtoimopnlc;eo tmt:b uesqtuiao(tnoi srot ni ocheiqomueattriiocn );
Air-RfauteTilho ge;a asn albyyvs oilsu Omres,aa ptpea rCaatlucsu;ol fat thmieao sc,nsf
drflyu gea speersk go ff uoeflk nowcna rbcoonn tfreon�Ot r seastCteo; n vcno,fi on
graviamneatrlitycvos o ilsu maentarliaycnsv dii sc e-Mvienrismaaui;rmr e quiinkr gpee rd
kgo fs oloirld i qfuuiMedil .n imquuma notfai irtrey q u_ifotrrhec edo mpcloemtbeu osft ion
onceu bmiecto efgr a sefouueDsle ;t erminoafpt eirocneo nfct aargbieonf nub eulrn itnog
C(ohCr O f roOmr saantael oyvrso ilsu mceotmrpiocsD iettieornm;oi ftn hapete irocne ntage
ocfa ribfnou nbe ulr ntiConO go2 Cr O fr omg raviAmneatlroyiffusc ei glsa sTehsee;n thalpy
anidn teernnaelorr fge ya cCtailoon(r;ohi ref aitcvi anloguf)ef Huieglah;ne ldro wcearl orific
Valouffeu Eexlpe;r imdeenttearlm oitfnh caeat lioovrnai lofuffieu cb e yBl o mCba lorimeter;
Experimdeentteanln oif'lnchaaetl iovoranilo fufgie ac s eFouueJslu ,n kgearcs'a sl orimeter;
adiabatic-tceommpe-rbaMutasuxtriiemoe;unx m p lopsrieosnsE unrterc;oh payn fogre s
reacmtiixntgu res. 66782-1
References 722
Appendices 724
NOMENCLATURE
A area
a sound velocity
B constant
C velocity
C constant
D diameter
E total_ energy
F force
ff total enthalpy, kJ
h enthalpy, kJ/kg
J · · mechanical equivalent of heat
K constant
m mass, mass flow rate
N speed
n index
p power
Q. total heat, kJ
q heat, kJ/kg
R gas constant
radius
r
s
total entropy, kJ/K
s entropy, kJ/kg K
T absolute temperature, K
t temperature, ·c
u
total internal energy, kJ
u internal energy, kJ/kg
V volume, m3
V specific volume, m3/kg
w
total work, kJ
w specific work, kJ/kg
1
BasiCcon ecptasn dD eifintions
Thermodynamics is the.science that deals with energy interactions between material
systems. In other words, -it is the science which deals with the transformation of energy
of all kinds from one Jorm to another. In fact, one very excellent definition of
thermodynamics is that it is the science of three "E" namely energy, entropy and
efl.Milibrium)Generally speaking, thermodynamics is primarily concerned with two forms
of energy heat and work. Cam_ot, Joule, Kelvin and Clausius were the main scientists
who developed this branch of science in the past century. In 1876, J.W. Gibbs advanced
classical thermodynamics to such an extent that in its scope it could be applied to almost
any physical or chemical phenomena.
The science of thermodynamics is basec;t on the four laws of thermodynamics known
as zeroth,first, second and third laws. Although, the formulation of these laws is simple
but their applications are remarkably extensive. And surprisingly, there is no
mathematical proof for. these laws. These laws were· deduced from experimental
observations and are based on logical reasonings.
· The application of thermodynamics is extr�mely wide. Its 12rinciples are used_jn the
designing of energy converting devices, such as steam engines, internal combustion
engines, steam and gas turbines.fuel cells, thermoelectric and thermionic generators . It
is also used in refrige�ors, air-conditio'lf!}, heat transfer, phase equilibrium or �n
equilibrium, etc. The credit for proving that mechanical work can be convened to heat
energy goes to James Joule and for converting heat into mechanical work to James Wau,
the inventor of steam engine.
When we consid�r matter from the macroscopic point of view, the subject is called
classical thermodynamics and when from microscopic point of view, it is called
statistical thermodynamics. In this volume, we will deal mainly with the subject of
classical thermodynamics.
In this chapter some basic concepts and definitions of various terminologie'S related
with the study of ther;nodynamics are presented.
1.1 Dimensions and Units
Dimensions and units are the main tools of engineering. The dimensions of a
.l..
physical uantity m_fil' be defined as the properties in terms of qua1ity not of mngnitude,
J2y which a physical ua!1tity 111ay be described. Length, area and volume arc all different
dimens10ns w 1ch describe certain measurnble characteristics of an ob_1cct. For example,
an area can be regarded as a length squared and a volume as a length cubed.
(A) = (L2) ( I. 1)
(V) = (/))
(1:2)
The right hand side of these equations shows dimensions of Lhe left hand side. These
equations state that the dimensions of an area and volume are equivalent to the