Exergy Analysis of Heating, Refrigerating, and Air Conditioning Exergy Analysis of Heating, Refrigerating, and Air Conditioning Methods and Applications Ibrahim Dincer and Marc A. Rosen AMSTERDAM (cid:129) BOSTON (cid:129) HEIDELBERG (cid:129) LONDON (cid:129) NEW YORK (cid:129) OXFORD PARIS (cid:129) SAN DIEGO (cid:129) SAN FRANCISCO (cid:129) SINGAPORE (cid:129) SYDNEY (cid:129) TOKYO Elsevier Radarweg29,POBox211,1000AEAmsterdam,Netherlands TheBoulevard,LangfordLane,Kidlington,OxfordOX51GB,UK 225WymanStreet,Waltham,MA02451,USA ©2015ElsevierInc.Allrightsreserved. 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ISBN:978-0-12-417203-6 LibraryofCongressCataloging-in-PublicationData AcatalogrecordforthisbookisavailablefromtheLibraryofCongress BritishLibraryCataloguinginPublicationData AcataloguerecordforthisbookisavailablefromtheBritishLibrary ForinformationonallElsevierpublications visitourwebsiteathttp://store.elsevier.com/ Acknowledgments The contributions of several graduate students are gratefully acknowledged, including Canan Acar, Sayantan Ghosh, Monu Malik, Farrukh Khalid, and FahadSuleman.Inparticular,wethankCananAcarforreviewingandrevising several chapters and checking for consistency. Inaddition,somematerialscomingfromMohammedAl-Ali,RezaSoltani,and Abdullah Al-Zahraniare acknowledged. Last but not least, we warmly thank our wives, Gulsen Dincer and Margot Rosen, and our children, Meliha, Miray, Ibrahim Eren, Zeynep, and Ibrahim EmirDincerandAllisonandCassandraRosen.Theyhavebeenagreatsource ofsupport and motivation. Ibrahim Dincerand Marc A. Rosen July2015 ix Preface Thisbookfocusesonapplicationsofexergymethodstotheheating,refrigerat- ing,andairconditioningindustriesandtheprimarytechnologiescomprising them,withtheaimofprovidinganenhancedunderstandingofthebehaviors ofsuchsystemsandbettertoolsfortheirimprovement.Heating,refrigeration, andairconditioningprocessesareveryimportantenergytechnologiesinmost countries and are often responsible for a significant portion of their energy utilization. Thus, it is beneficial to consider all available tools in efforts to improvedesigns,intermsofefficiency,environmentalperformance,econom- ics, and other factors. Exergyanalysisrepresentsarelativelyrecentandexcitinginnovationinthermo- dynamicsandenergysystems.Asamethodthatusestheconservationofmass andconservationofenergyprinciplestogetherwiththesecondlawofthermo- dynamics for the analysis, exergy analysis helps in the design, optimization, andimprovementofenergysystemslikeHVAC.Theexergymethodisauseful toolforfurtheringthegoalofmoreefficientenergyresourceuse,foritenables thelocations,types,andmagnitudesofwastesandlossestobeidentifiedand meaningfulefficienciestobedetermined.Exergymethodshavereceivednota- bleattentiononlyoverthelastfewdecades.Althoughthatattentionhasgrown during that period, it has remained somewhat limited and comprehensive applicationsofexergyanalysisintheheating,refrigeration,andaircondition- ing industriesremainneeded. Thebookseekstodescribecomprehensivelytheapplicationofexergymethods to heating, refrigerating, and air conditioning systems, so as to aid in their improvement. In doing so, the book containseight chapters. The relationsof the material to building energy systems and their management are stressed throughout. Chapter1describesenergyandexergymethodsandhowtheyareusedtoassess, design,andimprovetechnologiesandsystems.Fundamentalthermodynamic principles areexplainedand analysismethodologies basedonexergyare cov- ered in depth. In addition, extensions of these exergy-based methods to xi xii Preface environmental,economic,andsustainabilityassessmentsarecovered.Topro- videabroadercontext,theroleofheating,refrigerating,andairconditioningin regional systems like countries is discussed, including relevant energy, and exergy perspectives. InChapter2,energyandexergyanalysesofbasicheating,refrigeration,andair conditioningtechnologiesandsystemsarepresented.Includedareapplications ofexergyanalysistothecomponentscomprisingheating,refrigerating,andair conditioning, as well as psychrometric processes and overallsystems. Chapter3,Chapter4,Chapter5,andChapter6focusonarangeofindustrial systems and applications of heating, refrigeration, and air conditioning. Chapter3focusesontheuseofexergymethodsinindustrialheatingandcool- ingandthediverserangeofprocessesthatcanbeusedforthoseactivities.Heat pump systems are introduced but are examined in much greater depth in Chapter 4. Cogeneration, trigeneration, and multigeneration, as well as inte- grated energy systems and district heating and cooling, are covered in Chapter 5. Chapter 6 describes how exergy methods are applied to heat and coldstoragesystems,coveringtherangeofsuchtechnologiesthatfindapplica- tions in buildings. InChapter7,buildingHVACsystemsbasedonrenewableenergyaredescribed andseveralcasestudiesareconsideredforillustration.Theutilizationofrenew- ableandsustainableenergyinplaceofconventionalenergyresourceslikefossil fuelsisanimportantextensionofthematerialintheprecedingchapterssince we feel that renewable and sustainable energy systems represent the future of energy systems in general and for heating, refrigeration, and air conditioning in particular. In Chapter 8, several illustrations are described of exergy-based methods for improving heating, refrigeration, and air conditioning systems. The methods coveredincludedesignforresponsibleenergyandenvironmentmanagement, lifecycleassessment,energyretrofits,andenergysubstitution,thestrategicinte- gration of energy systems, and the allocation of environmental emissions. ThesearelinkedtothematerialinChapter7bylinkingthemtotheutilization of renewableand sustainableenergy. Incorporated throughout are many illustrative examples and case studies, which provide the reader with a substantial learning experience, especially in terms of practicalapplications. Theappendixescontainunitconversion factorsandtablesandchartsofther- mophysicalpropertiesofvariousmaterialsintheInternationalSystemofUnits (SI). A glossaryof exergy-related terminology is also provided. Preface xiii Referencesareincludedtodirectthereadertosourceswheremoredetailscanbe foundandtoassistthereaderwhoissimplycurioustolearnmore.Therefer- ences can also help identify information on topics not covered comprehen- sively in the book. Asaresearch-orientedtextbook,thisvolumeincludestheoreticalandpractical featuresoftennotincludedinsolelyacademictextbooks.Thisbookismainly intended for use by advanced undergraduate or graduate students in several engineering and nonengineering disciplines and also as an essential tool for practitioners in HVAC disciplines. Theory and analysis are emphasized throughout this comprehensive book, reflecting new techniques, models, andapplications,togetherwithcomplementarymaterialsandrecentinforma- tion.Coverageofthematerialisextensive,andtheamountofinformationand datapresentedissufficientforadvancedcoursesrelatedtoheating,cooling,and airconditioning—andadvancedtechnologiesbeingappliedintheseareas—or asasupplementforcoursesonappliedthermodynamics.Webelievethatthis bookwillbeofinteresttostudentsandpractitionersandindividualsandinsti- tutions who are interested in exergy and its applications to heating, cooling, andairconditioningaswellasthevariousnewtechnologiesandmethodsthat areincreasinglyfindinguseinthese areas.Thisvolume isalsoavaluableand readablereferenceforanyonewhowishestolearnaboutexergymethodsand/ or advanced heating, cooling,and airconditioning. Wehopethisbookallowsexergymethodstobemorewidelyappliedtoheat- ing,refrigerating,andairconditioningindustriesandboththetraditionaland new technologies being applied in them. The book thereby provides an enhancedunderstandingofthebehaviorsofheating,refrigerating,andaircon- ditioning systems and enhanced tools for improving them. By exploiting the benefits of applying exergy methods to these systems, we believe they can be mademoreefficient,clean,andsustainableandhelphumanityaddressmany ofthe challenges it faces. Ibrahim Dincerand Marc A. Rosen July2015 CHAPTER 1 Exergy and its Ties to the Environment, Economics, and Sustainability 1.1 INTRODUCTION Heating,refrigeration,andairconditioningprocessesaretreatedasimportant energy technologies in most countries and are often responsible for a signi- ficantportionoftheirenergyutilization.Applyingexergymethodstotechno- logies for the heating, refrigerating, and air conditioning can provide a better understanding of their behaviors and enhanced tools for improving them.Thisuseofexergyanalysisnotonlyisadvantageousbutalsoisprudent, sinceitisusefultoconsiderallavailabletoolsineffortstoimprovedesigns,in termsofefficiency,environmentalperformance,economics,andotherfactors. Exergy analysis represents a recently rediscovered and exciting innovation in thermodynamics and energy systems. Exergy methods, basic to enhanced and combined models, have received notable attention only over the last few decades. Although such attention has grown during that period, it has remainedlimitedandapplicationsofexergyanalysisintheheating,refrigera- tion, and air conditioning industries, although they have increased notably, wouldbenefitfromanenhancedfocusandaconsolidationoftheinformation. The applications of exergy methods to heating, refrigerating, and air conditioning systems are described in a detailed and comprehensive manner inthisbook,withtheintentofenhancingunderstandingandaidinginprocess assessments and improvements. Thebookstartsbydescribingenergyandexergymethodsandhowtheyareused toassess,design,andimprovetechnologiesandsystems.Fundamentalthermo- dynamicprinciplesareexplainedandanalysismethodologiesbasedonexergy arecoveredindepth.Inaddition,extensionsoftheseexergy-basedmethodsto environmentalassessmentsandeconomicevaluationsarecovered.Toprovide a broader context, the role of heating, refrigerating, and air conditioning in regional systems like countries is discussed, including relevant energy and exergyperspectives. 1 ExergyAnalysisofHeating,Refrigerating,andAirConditioning.http://dx.doi.org/10.1016/B978-0-12-417203-6.00001-6 ©2015ElsevierInc.Allrightsreserved. 2 CHAPTER 1: Exergy and its Ties to the Environment, Economics, and Sustainability Next, energy and exergy analyses of basic heating, refrigeration, and air conditioningtechnologiesandsystemsarepresented.Includedareapplications of exergy analysis to the components comprising heating, refrigerating, and air conditioning, as well as overall systems. A diverse range of processes are considered, including industrial heating and cooling, drying, building energy management, cogeneration and trigeneration, district heating and cooling, and thermal storage. Measures for improving heating, refrigeration, and air conditioning systems are also described. Renewable and sustainable energy systems are covered throughout not only because of their expanding usage but also because they likelyrepresent the future of energy systems. Thebookclosesbydescribingandassessingexergy-basedmethodsforimprov- ingheating,refrigeration,andairconditioningsystems.Themethodscovered includedesignforresponsibleenergyandenvironmentmanagement,lifecycle assessment,energyretrofits, and energy substitution.Thelatterisextended to the utilization of renewable and sustainable energy in place of conventional energyresourceslike fossil fuels. 1.2 WHY EXERGY? Energyuseispervasiveinlife,andthereisastrongrelationbetweenenergyand prosperity. Throughout much of history, the emergence of civilizations has beencharacterizedbythediscoveryandeffectiveapplicationofenergytohelp meet society’s needs. The desire of people to sustain and improve their well- beingispossiblythebiggestdriverofthegrowthinworldwideenergydemand. Therefore,meetingthedemandforenergyservicesinaclean,efficient,secure, and reliableway is animportant challenge. Energy analysis is the traditional method of assessing the way energy is used inoperations(e.g.,physicalorchemicalprocessingofmaterials,heattransfer, and energy conversion). Energy analysis is based on the first law of thermo- dynamics (FLT) and usually entails performing energy balances and evaluat- ing energy efficiencies. The FLT embodies the principle of conservation of energy, which states that, although energy can change form, it can be neither created nor destroyed. However, this law provides no information about the direction in which processes can spontaneously occur, that is, it does not explain reversibility aspects of thermodynamic processes. An energy balance also cannot explain the degradation of energy or resources during a process and does not quantify the usefulness or quality of energy and material quan- tities(e.g.,input,product,andwasteflowsforasystem).TheFLTprovidesno information about the inability of any thermodynamic process to convert heat fully into mechanical work or any insight into why mixtures cannot 1.2 Why Exergy? 3 spontaneously separate or unmix themselves. Another principle to explain these phenomena and to characterize the availability of energy is required to do this. TheexergymethodofanalysisovercomesmanyofthelimitationsoftheFLT. TheconceptofexergyisbasedonboththeFLTandthesecondlawofthermo- dynamics (SLT). Exergy analysis clearly indicates the locations, nature, and causesofenergydegradationinaprocessandthereforecanhelpimproveapro- cessortechnology.Exergyanalysiscanalsoquantifythequalityofenergydur- ing heat transfer. The primary aim of exergy analysis is usually to provide meaningful efficiencies(i.e.,exergyefficiencies)andthecausesandtruemag- nitudes ofexergylosses. Itisimportanttodistinguishbetweenexergyandenergyinordertoavoidcon- fusionbetweenexergyanalysisandtraditionalenergy-basedmethodsofanal- ysis and design. Table 1.1, which compares energy and exergy in a general manner, can help in making such a distinction. Energy flows into and out of a system with mass flows, heat transfers, and work interactions (e.g., work associated with shafts and piston rods). Energy is conserved, in line with the FLT. Exergy, although similar in some respects, is different. It loosely repre- sentsaquantitativemeasureoftheusefulnessorqualityofanenergyormate- rial substance. More rigorously, exergy is a measure of the ability to do work (or the work potential) from a quantity or flow (mass, heat, and work), in a specifiedenvironment.Akeyattributeofexergyisthatitpermitscomparisons on a common basis of quantities (inputs and outputs) of different types. Table1.1 GeneralComparisonofEnergyandExergy Energy Exergy (cid:129) Dependentonpropertiesofquantity(e.g.,matterand (cid:129) Dependentonbothpropertiesofquantity(e.g.,matter energy)andindependentofpropertiesofareference andenergy)andpropertiesofareferenceenvironment environment (cid:129) Nonzeroinvaluewheninequilibriumwiththe (cid:129) Zeroinvaluewhenatthedeadstate,thatis,incomplete referenceenvironment equilibriumwiththereferenceenvironment (cid:129) Conservedforallprocesses,thatis,canbeneither (cid:129) Conservedforreversibleprocessesandnonconserved destroyednorproduced forrealprocesses,thatis,canbeneitherdestroyednor producedinareversibleprocessbutisalwaysdestroyed (consumed)inanirreversibleprocess (cid:129) Appearsinmanyforms(e.g.,kineticenergy,potential (cid:129) Appearsinmanyforms(e.g.,kineticexergy,potential energy,work,heat)andismeasuredinthatform exergy,work,thermalexergy)andismeasuredonthe basisofworkequivalentorabilitytoproducework (cid:129) Ameasureofquantity,butnotquality (cid:129) Ameasureofquantityandquality (cid:129) BasedontheFLT (cid:129) BasedonacombinationoftheFLTandtheSLT