Page - 345 - in Emerging Technologies for Electric and Hybrid Vehicles

energies Review Progress inHeatPumpAirConditioningSystemsfor ElectricVehicles—AReview QinghongPeng1,2 andQunguiDu1,* 1 SchoolofMechanicalandAutomotiveEngineering,SouthChinaUniversityofTechnology, Guangzhou510641,China;pqh0720@sina.com 2 DepartmentofMechanicalandElectricalEngineering,ShundePolytechnic,Foshan528333,China * Correspondence: ctqgdu@scut.edu.cn;Tel./Fax:+86-20-8711-2553 AcademicEditor:VincentLemort Received: 24October2015;Accepted: 17March2016;Published: 25March2016 Abstract: Electric vehicles have become increasingly popular in recent years due to our limited natural resources.Asaresult, interest inclimatecontrol systemsforelectricvehicles is risingrapidly. According to avarietyof research sources, theheatpumpair conditioning systemseems tobea potential climate control systemfor electricvehicles. In thispaper, anextensive literature review has beenperformedon theprogress in heat pumpair conditioning systems for electric vehicles. First, a reviewofapplicationsofalternativeenvironmentally friendlyrefrigerants inelectricvehicles is introduced. This is followedbya reviewof other advanced technologies, suchas the inverter technology, innovative components and the system structure of the heat pumpair conditioning systemforelectricvehicles. Lastly, recentdevelopments inmultiplesourceheatpumpsystemsare presented. Theuse of these advanced technologies canprovide not only sufficient refrigerating capacity for theelectricvehicle, butalsohigher climate control systemefficiency.Webelieve that idealpracticalairconditioningforelectricvehiclescanbeattainedinthenearfutureasthementioned technicalproblemsaregraduallyresolved. Keywords: airconditioning;heatpump;electricvehicle;heat source 1. Introduction Duetopollutionreductionandgreenhousegasemissionreductionpolicies, fullyelectricvehicles (EVs)arebeingstronglypromoted. InbothEVsandinternalcombustionenginevehicles,acomfortable cabinenvironment isessential forpassengers.However, inconsiderationof theabsenceofheat from the engine coolant in EVs, an innovative air conditioning (AC) systemdesignmust be provided. Inrecentyears, solutions for theACsysteminfullyEVshavebeenstudiedextensively. SomeauthorshavepresentedthethermoelectricAC,wherebythevehiclecabincanbecooledand heatedbythermoelectricmodules,whichhave theadvantageofhavingnomovingparts,nonoise, long life, small sizeandprecise temperaturecontrol [1,2],but this technologyhasnotbeenaccepted due topoor efficiency. Currently, it is used only in seat heating and cooling in some luxury cars. Inaddition, this technology isapplied toshort-distancesmallEVs inviewof limitedresourcesandthe lowfigureofmeritof thermoelectricmaterials [3]. The simplest solution is touseanelectric compressor insteadof amechanical compressor for cooling,meanwhileapositive temperaturecoefficient (PTC)heater isadaptedtoprovideheating in placeof theenginecoolantheatercore [4–6]. A42VelectricACsystemwasproposed. Thesystem consisted of a compressor, a blower, an integrated PTCheater, an inverter, pipes and someheat exchangers [5]. The cabin temperature would initially decline quickly and then change more consistently. Theresults showedthe42VelectricACsystemcouldmaintainastableandcomfortable interior environmentunderhotweather conditions. Moreover, it couldachieve a relativelybetter Energies 2016,9, 240;doi:10.3390/en9040240 www.mdpi.com/journal/energies345