Performance comparison of thermal management systems for electric vehicles using single- and dual-loop indirect heat pumps with propane

Propane refrigerant is considered for use in heat pumps to improve driving range and reduce the environmental impact of electric vehicles. When using propane, single- and dual-loop indirect heat pumps should be employed to satisfy safety regulations. However, few comparative performance analyses of single- and dual-loop heat pumps using propane have been performed to determine a more efficient indirect system for electric vehicles. In this study, the energy, economic, and environmental performances of thermal management systems adopting single- and dual-loops with waste-heat recovery modes in electric vehicles are compared under cooling and heating conditions. With heat recovery from the battery and motor, the coefficients of performance of the single-loop in the heating and cooling conditions are higher than those of the dual-loop by 8.3 − 11.0 % and 38.0 − 49.5 %, respectively, at a fixed capacity. Additionally, the life cycle cost and climate performance of the single-loop are lower than those of the dual-loop by 9.4 % and 22 %, respectively, owing to the superior coefficient of performance. Overall, when using propane refrigerant in an indirect system for electric vehicles, the single-loop outperforms the dual-loop in terms of the coefficient of performance, life cycle cost, and life cycle climate performance even with its drawback of larger charge amount.