Winter performance analysis of multi-mode integrated thermal management system based on thermodynamics

Abstract

The thermal management system plays a critical role in pure electric vehicles to ensure the comfort of cabin and the thermal safety of battery, motor and controller, but it consumes lots of energy at the same time. In order to improve the energy utilization efficiency of the whole vehicle, a topology of the multi-mode integrated thermal management system (MITMS) is constructed in this paper by combining heat pump, battery thermal management and motor waste heat recovery. Focusing on the winter condition, simulations via AMESim have been conducted for the MITMS to assess its performance working as series and parallel structures. The results show that the MITMS with a series structure (series system) has better thermodynamic performance than that of the parallel one (parallel system). To be specific, compared with the parallel system, the exergy efficiency of the series system is promoted by 23.9% on average, and the coefficient of performance (COP) is increased by 13.5% under the condition of optimal refrigerant charge. Moreover, the series system has better heating performance, and its battery temperature rising rate in winter is also significantly improved. Based on the MITMS winter mode switching strategy formulated in this work, the performance of waste heat recovery is tested. Under low-temperature conditions, the heating capacity is increased by 22.75% on average. The MITMS test is carried out under the CLTC-P driving cycle. The results show that, compared with the baseline system, the battery temperature increases significantly and the SOC recovers by 2.68%, which further verifies the practical feasibility of the present system.