Seite - 355 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2016,9, 240 Figure11.Schematicdiagramof thedualheatsourceheatpump[83]. Theycomparedtheheatingperformanceofthedualsourceheatpumpinvariousoperationmodes: air source-only,wasteheat-onlyanddualheat sources. Theexperimental results indicated that the heatingcapacityandCOPinthedualsourceheatpumpwereincreasedby20.9%and8.6%,respectively, comparedto thoseof theair source-onlyheatpumpsystem,while itbecameveryclose to thewaste heat-onlymodeat lowoutdoor temperature.Cho et al. [85]measuredtheheatingperformanceofa coolantsourceheatpump,whichusedwasteheat fromelectricdevicesonanelectricbus.Asshown inFigure12, the test setupwascomposedofarefrigerant loop,anaircirculation loop,andacoolant loop. Bothanevaporatorandacondenser,withplateheatexchangers,were installedfor thepurpose of exchangingheat between the refrigerant and the coolant sourceusing thewaste heat from the electricdevices. Thesameheat transfermechanismwasadopted in [86,87]. Besidesof the feasibilityof integratingaheatpumpinto theACsystemof theEV,bothcoolingandheatingperformancesunder variousexperimental conditions, includingvariations inoutdoorandindoor temperatures, thewater flowrate for the condenser and theevaporator sides,were investigated [86]. The systemwasalso optimizedbyvaryingtherefrigerantchargeandthecompressor frequencyaswellasusingacontrol algorithmforoperationalenergymanagement. TheproposedheatpumpACsystemcouldmeet target powercapacitieswhichhadbeensetas28kWofcoolingand26kWofheatingwithCOPsofmorethan 1.6 for coolingand2.6 forheating,whichwererequired for systemenergyefficiencyandcustomer comfort [87]. Thetargetenergyconsumptionbycoolingandheatinghadbeenmetat less than20% and25%of the totalelectricalenergyconsumptionof theelectricbus, respectively. Zou et al. [88]also presentedaheatpumpACsystemcoupledwith thebatterycoolingsystem.Theauthorsdeclaredthat thebatterydissipationheatwasnotonlyausefulheat source for theheatpumpACsystem,especially at lowoutdoor temperature,butalsoanadditionalcooling loadsince theambient temperaturewas toohightodissipate thebatteryheat to theambientairdirectly. Figure12.Heattransfermechanismoftheheatpumpsystemusingwasteheatfromelectricdevices[85]. 355