Efficiency Evaluation of Energy Systems

176 Pages·2012·1.849 MB·English

by  Mehmet Kanoğlu, Yunus A. Çengel, İbrahim Dinçer (auth.)

SpringerBriefs in Energy
Forfurther volumes:
http://www.springer.com/series/8903

Mehmet Kanog˘lu Yunus A. C¸engel
l
˙
Ibrahim Dinc¸er
Efficiency Evaluation
of Energy Systems
MehmetKanog˘lu YunusA.C¸engel
DepartmentofMechanicalEngineering DepartmentofMechanicalEngineering
UniversityofGaziantep UniversityofNevada
Gaziantep,Turkey Reno,NV,USA
I˙brahimDinc¸er
DepartmentofMechanicalEngineering
UniversityofOntarioInstitute
ofTechnology
Oshawa,ON,Canada
ISSN2191-5520 ISSN2191-5539(electronic)
ISBN978-1-4614-2241-9 ISBN978-1-4614-2242-6(eBook)
DOI10.1007/978-1-4614-2242-6
SpringerNewYorkHeidelbergDordrechtLondon
LibraryofCongressControlNumber:2012932274
#MehmetKanog˘lu,YunusA.C¸engel,I˙brahimDinc¸er2012
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Preface
Efficiencyhasbecomeaprimetopicinenergystudies,andhasattractedagreatdeal
ofattentionfromalldisciplinesfrommechanicalengineeringtophysicsandfrom
electricalengineeringtoarchitecture.Efficiencycalculationsarecommonlyusedto
evaluate systems, applications, processes, and services in every sector, ranging
fromindustrialtoresidentialandfromutilitytocommercial.Efficiencyevaluation
isconsideredakeycomponentinassessingtheperformanceofenergysystems.
The two main principles of thermodynamics are the first and second laws of
thermodynamicswhichleadtoenergyefficiencyandexergyefficiency,respectively.
A few decades ago, a thermodynamic analysis involved the evaluation of energy
efficienciesonlywithoutconsiderationofsecondlaweffects.Growingawarenessof
limited energy resources and concern for a sustainable economy have made it
necessarytoperformmorerefinedthermodynamicsstudies,whichrequiredarealistic
assessmentofthedegradationofenergyduetoirreversibilities.Suchanecessityhas
madeexergyefficiencyanindispensabletoolforperformanceevaluation.
This book primarilycoversenergy andexergy efficiencies andtheir associated
discussion,andprovidesthenecessarytoolstoanalyzevarioussystemsandappli-
cations and to make comparisons. Coverage of the material is extensive, and the
amount of information and data presented is sufficient for detailed studies. This
book should be of interest to students, researchers, engineers, and practitioners in
theareaofenergyaswellaspeoplewhoareinterestedinevaluatingandimproving
energy systems and applications. The book should also serve as a valuable refer-
ence and source book for anyone who wishes to learn more about efficiency
assessment.
The first chapter addresses general aspects of energy, efficiency, environment,
and sustainable development as well as linkages between them with some
examples.Chapter2introducesboththefirstandsecondlawsofthermodynamics
and discusses their role and use in practical applications. Chapter 3 goes further
and introduces both energy and exergy efficiencies as valuable tools for perfor-
mance evaluations and illustrates their use through some examples. It also puts
these efficiencies in perspective, and highlights the differences between them.
Chapter 4 deals specifically with energy conversion efficiencies and introduces
v
vi Preface
basic formulations for use in common applications. Chapter 5 presents thermody-
namic modeling of power plants and their performance assessment using both
energy and exergy efficiencies. Finally, analysis and performance assessment is
extended in Chap. 6 to refrigeration systems, again through energy and exergy
efficiencies.Incorporatedthroughoutthisbookisawiderangeofexamplesfroma
diverseareaofpracticalapplications.
Gaziantep,Turkey MehmetKanog˘lu
Reno,NV,USA YunusA.C¸engel
Oshawa,ON,Canada I˙brahimDinc¸er
Contents
1 Efficiency,Environment,andSustainability............................ 1
1.1 Introduction.......................................................... 1
1.2 Energy,Exergy,Environment,andSustainableDevelopment...... 1
1.3 EfficiencyandEnergyManagement................................. 6
2 TheFirstandSecondLawsofThermodynamics....................... 9
2.1 Introduction.......................................................... 9
2.2 EnergyChangeandEnergyTransfer................................ 10
2.2.1 MassTransfer................................................ 11
2.2.2 HeatTransfer................................................. 11
2.2.3 Work ......................................................... 11
2.3 TheFirstLawofThermodynamics.................................. 12
2.4 TheSecondLawofThermodynamics............................... 14
2.5 Entropy............................................................... 16
2.5.1 EntropyBalance.............................................. 18
2.6 Exergy................................................................ 19
2.6.1 WhatIsExergy? ............................................. 20
2.6.2 ReversibilityandIrreversibility.............................. 21
2.6.3 ReversibleWorkandExergyDestruction................... 22
2.6.4 ExergyChange............................................... 22
2.6.5 ExergyTransferMechanisms................................ 23
2.6.6 ExergyBalance .............................................. 24
3 EnergyandExergyEfficiencies.......................................... 27
3.1 Introduction.......................................................... 27
3.2 EfficienciesofCyclicDevices....................................... 30
3.3 EfficienciesofSteady-FlowDevices................................ 36
3.3.1 Turbine....................................................... 36
3.3.2 Compressor................................................... 38
vii
viii Contents
3.3.3 Pump........................................................ 40
3.3.4 Nozzle....................................................... 42
3.3.5 ThrottlingValve............................................. 43
3.3.6 HeatExchanger............................................. 44
3.3.7 MixingChamber............................................ 48
3.3.8 ElectricResistanceHeating................................. 49
4 EnergyConversionEfficiencies......................................... 55
4.1 ConversionEfficienciesofCommonDevices...................... 55
4.1.1 ElectricResistanceHeater.................................. 55
4.1.2 ElectricWaterHeater....................................... 56
4.1.3 NaturalGasWaterHeater .................................. 56
4.1.4 CombustionEfficiency...................................... 56
4.1.5 HeatingValues.............................................. 57
4.1.6 BoilerEfficiency............................................ 57
4.1.7 GeneratorEfficiencyandOverallEfficiency............... 59
4.1.8 LightingEfficacy............................................ 59
4.2 EfficienciesofMechanicalandElectricalDevices................. 60
4.3 CryogenicTurbineEfficiencies..................................... 62
5 EfficienciesofPowerPlants............................................. 69
5.1 Introduction......................................................... 69
5.2 EfficienciesofVaporPowerCycles................................ 70
5.3 EfficienciesofGasPowerPlants................................... 74
5.4 EfficienciesofCogenerationPlants................................. 77
5.4.1 Steam-Turbine-BasedCogenerationPlant.................. 79
5.4.2 Gas-Turbine-BasedCogenerationPlant.................... 81
5.5 EfficienciesofGeothermalPowerPlants........................... 82
5.6 EnergeticandExergeticAnalysesofaPhotovoltaicSystem...... 89
6 EfficienciesofRefrigerationSystems................................... 95
6.1 RefrigeratorsandHeatPumps...................................... 95
6.1.1 HeatPumpEfficiencies..................................... 96
6.1.2 TheCarnotRefrigerationCycle............................ 98
6.2 SecondLawAnalysisofVapor-Compression
RefrigerationCycle................................................. 100
6.3 EnergyandExergyEfficienciesofVapor-Compression
HeatPumpCycle.................................................... 106
6.4 AbsorptionRefrigerationCycle..................................... 109
6.5 LiquefactionofGases............................................... 111
6.5.1 Linde–HampsonCycle...................................... 112
6.5.2 PrecooledLinde–HampsonLiquefactionCycle............ 118
Contents ix
6.6 EfficiencyAnalysisofPsychrometricProcesses................... 123
6.6.1 BalanceEquationsforCommonAir-Conditioning
Processes...................................................... 123
6.6.2 HeatingorCooling.......................................... 126
6.6.3 HeatingwithHumidification................................ 129
6.6.4 CoolingwithDehumidification............................. 130
6.6.5 EvaporativeCooling........................................ 130
6.6.6 AdiabaticMixingofAirStreams........................... 131
AppendixA..................................................................... 133
AppendixB..................................................................... 149
Nomenclature.................................................................. 161
References...................................................................... 165
Index............................................................................ 167