Performance of organic Rankine cycle using waste heat from electric vehicle battery

Abstract

The battery of an electric vehicle (EV) must be appropriately cooled to prevent battery overheating while driving. Waste heat from EV batteries is typically recovered and used for indoor heating instead of generating electricity. In this study, an organic Rankine cycle (ORC) using electric vehicle (EV) battery heat as a heat source was designed with a particular focus on the turbine. The mean-line design of a single-stage axial-flow turbine was performed, and the turbine performance was analyzed. The isentropic efficiency of the designed turbine was 0.75, and the electrical power was approximately 100 W. The thermal efficiency of the ORC was 4.23 % at a working fluid temperature of 25 degrees C at the condenser outlet. This used 2.24 kW of battery heat, which is approximately 78 % of the EV battery waste heat considered in this study. Therefore, applying the ORC to an EV recovers a significant amount of waste heat from the battery to reduce the battery temperature and generate electricity. Furthermore, we present an operation method that can improve the thermal efficiency of the EV ORC and is applicable in situations where the evaporation and condensation are not constant.