Fundamentals of Engineering Thermodynamics

440 Pages·2019·19.334 MB·\440

by  V. Babu (Author)

FUNDAMENTALS OF ENGINEERING
THERMODYNAMICS
V.Babu
Professor
DepartmentofMechanicalEngineering
IndianInstituteofTechnology,Madras,INDIA
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Dedicated to my wife
Chitra without whose
patience, understanding
and support, this book too
would never have been
written

PREFACE
Iamhappytocomeoutwiththesecondeditionofthebookonthefundamentalsof
EngineeringThermodynamics. Fivenewchaptershavebeenaddedandthechapter
onThermodynamiccycles(Chapter10inthepreviousedition)hasbeencompletely
rewritten. ThenewchapteronExergydiscussesthenotionofexergyandhowitcan
beusedasaperformancemetricforanyprocess-cyclicorotherwise,inamuchmore
generalsensethantheisentropicefficiency. TherevisedchapteronThermodynamic
cycles now includes, the Otto, Diesel and Dual cycles. Second law analysis of all
the cycles as well as the individual components are also presented now, which is
a unique feature. In the chapter on psychrometry, rather than giving illustrations
ofthepsychrometricchartalongsideeachexample, croppedimagesoftherelevant
part of the chart itself has been given. The image also shows how the values for
the various properties are retrieved. Hopefully, students would find this helpful
when they are using the chart to solve the examples on their own. The chapter
on Combustion, contains worked examples on solid, liquid (including blends) and
gaseousfuelsandcombustorsinpracticaldevicessuchasgasturbinesandICengine.
The chapter on Gas phase chemical equilibrium starts with a broad introduction to
thenotionofequilibrium–mechanical,thermalandchemical.Someoftheexamples
inthischapterbuildontheexamplesfromthepreviouschapterwiththeobjectiveof
demonstrating the difference between a stoichiometric analysis and an equilibrium
analysis. Several examples involving two and three reactions simultaneously in
v
vi PREFACE
equilibriumarealsoworkedout. ThechapteronCompressibleflowinnozzleshas
been adapted from my earlier text book on Gas dynamics. Unique features of this
chapteraretheillustrationinaP-vdiagramalongsidethecustomaryillustrationina
T-sdiagramandthesectionontheflowofsteamthroughnozzles.
Onceagain,IwouldliketothankmyteachersfromwhomIhavebenefitedgreatly.
Inparticular,IwouldliketothankSri. S.Sundaresan,myhighschoolteacher,Prof.
R.Bodonyi,Prof. M.FosterandProf. T.ScheickoftheOhioStateUniversity,who,
as teachers, inspired me to a great extent. I would also like to place on record my
appreciation of my advisor, friend and mentor, Prof. S. Korpela of the Ohio State
University. Hehasalwaysbeenandwillalwaysbeasourceofstrengthandsupport.
I wish to express my heartfelt gratitude to my parents who endeavored so much
togivemeagoodeducation. Theyhavegivenalottomebutreceivedverylittlein
return. ThanksarealsoduetomysonAravindhformanyengagingdiscussionson
thetopicsdiscussedinthisbookandalsoforhishelpwithsomeoftheillustrations
inChapter12aswellasinsolvingsomeoftheworkedexamplesusingCanteraand
MATLAB.
I wish to thank the readers who pointed out errors in the previous edition. These
have been corrected in this edition. If you find any more errors or if you have
any suggestions for improving the exposition of any topic, please feel free to
communicatethemtomeviae-mail([email protected]). Ialsowishtoplace
on record my sincere appreciation and gratitude to Linrick.com for allowing me to
usetheirpsychrometricchartinthebook.
V.Babu
PREFACE TO THE FIRST EDITION
I am happy to come out with this book on the fundamentals of Engineering
Thermodynamics. The material in this book has grown out of my lecture notes
for the freshman undergraduate course on Engineering Thermodynamics that I have
been teaching at IIT Madras for nearly twenty years now. The decision to finally
write this book was in large part due to the positive feedback that I have received
during these years from students who took the course and their expressed desire to
see the material taught in class being published as a book.
Since the course was a freshman course and almost all students in India study
thermodynamics as a part of their Physics and Chemistry courses at the Higher
Secondary level, perhaps the biggest challenge that I faced while teaching this
course was trying to make them “unlearn” many concepts that they had learnt
incorrectly. Consequently, readers from other countries may find the excessive
emphasis on concepts that are taken for granted elsewhere, puzzling or surprising or
even unwarranted! I have not changed this emphasis while writing the book because
of the belief that it will still benefit many students who, for one reason or another,
do not ask such questions in class and are unable to find the answers outside the
classroom either.
One of the unique features of the book is the primary importance given to the system
vii
viii PREFACETOFIRSTEDITION
approachwiththecontrolvolumeapproachbeingdevelopedasanextensionofthe
same and not as an alternative approach on an equal footing. This has been done
formassbalance,energybalanceandentropybalanceforflowprocesses-steadyas
wellasunsteady.Anotheruniquefeatureisthelargenumberofexamplesusingfinite
reservoirsinChapter8. Ihadtwoobjectivesinmindfordoingthis-first,inreallife,
allreservoirsarefiniteandsostudentsshouldbeabletocarryoutanalysisinvolving
themquitecomfortablyandsecond,thisallowsthenotionofexergytobeintroduced
quite naturally, thereby preparing the students for the next level course where they
willlearnthisindetail. Ihavealsonotgivenanyendofchapterproblems,choosing,
instead to work out numerous examples in each chapter. Many of the examples
are continued across chapters, in order to illustrate increasing levels of complexity
witheachnewchapter. Itismysincerewishthatthereaderswillbenefitalotfrom
attempting the examples on their own and then comparing their work with what is
giveninthebook.
I have given a list of books at the end (in alphabetical order) that I like. In this
context, I would like to single out the book by Prof. Moran and co-authors for
special mention. I had the fortune to attend Prof. Moran’s lectures in 1987 while
I was preparing for my PhD qualifying exam as a graduate student at the Ohio
State University in the Department of Mechanical engineering. The clarity of the
lectures-whatwassaidandwhatwaswrittenontheboard,leftmeawe-struck. Not
surprisingly,thebookthatProf. Moranhaswrittenonthesubjectalsohasthesame
clarityandisaparticularfavoriteofmine.This,combinedwiththefactthatthereare
quiteafewexcellentbooksonthesubject(afewofwhicharegivenintheSuggested
Reading)hadmademereluctantforlongtoundertakethetaskofwritingabookon
the same topic. However, as I mentioned earlier, the encouragement from students
whohavegonethroughmylectureshasfinallymademeovercomethisreluctance.It
ismyhopethatstudentswillfindthisbookasteppingstonetoread,learnfromand
appreciateotherwonderfultextbooksavailableonthesametopic.
Onceagain,IwouldliketothankmyteachersfromwhomIhavebenefitedgreatly.
Inparticular,IwouldliketothankSri. S.Sundaresan,myhighschoolteacher,Prof.
R.Bodonyi,Prof. M.FosterandProf. T.ScheickoftheOhioStateUniversity,who,
as teachers, inspired me to a great extent. I would also like to place on record my
appreciation of my advisor, friend and mentor, Prof. S. Korpela of the Ohio State
University. Hehasalwaysbeenandwillalwaysbeasourceofstrengthandsupport.
I wish to express my heartfelt gratitude to my parents who endeavored so much
to give me a good education. They have given a lot to me but received very
little in return. Thanks are also due to my son Aravindh for many engaging
discussions on the topics discussed in this book while he was an undergraduate
student in Mechanical engineering. He was able to provide a unique perspective
on the difficulties and challenges faced by students trying to learn Engineering
Thermodynamics. Accordingly,Ihavemadesubtlechangesinthemannerinwhich
thematerialisdeveloped. Hopefully,studentstryingtolearnthesubjectforthefirst
PREFACETOFIRSTEDITION ix
timewillfindthebookeasytoreadandlearnfrom.
I wish to express my sincere appreciation to my colleague Dr. V. Raghavan
for painstakingly working out the examples and correcting the errors therein and
for numerous valuable suggestions. If any errors remain, I am entirely respon-
sible. If you find any errors or if you have any suggestions for improving the
exposition of any topic, please feel free to communicate them to me via e-mail
([email protected]).
V.Babu