Performance Estimation of HVAC System using Secondary Loop Heat Pump System for Electric Vehicles

Abstract

In recent years, because of the regulations on the use of high Global Warming Potential(GWP) HFC refrigerants, alternative refrigerants for vehicle HVAC are under development for the application in the heat pump system for vehicles. Furthermore, since the energy consumed by the HVAC system significantly affects the driving range of EVs, both the heating/cooling performance and the energy consumption of the heat pump system should be considered to use the alternative refrigerants for the EV HVAC system. In this study, R290 refrigerant is selected as working fluid in heat pump system for the EV HVAC system. Due to the flammability of R290, secondary loop heat pump system is selected to isolate the R290 cycle in a separate module. Based on the secondary loop heat pump system using R290, an integrated 1-D EV model is developed to estimate the performance and the energy consumption of the heat pump system over a driving cycle. The integrated 1-D EV model includes EV powertrain model, heat pump system model, battery thermal management system model, and cabin thermal model which are developed in GT-Suite environment. Each system model is validated with experimental data. The integrated model is used to estimate the driving range of the EV and the performance of the HVAC system with various ambient temperatures during driving cycle. Also, the secondary loop heat pump system using R290 is compared with the system using R134a based on the performance and energy consumption over a driving cycle.