Experimental investigation on a heating-and-cooling difunctional battery thermal management system based on refrigerant

Abstract

Li-ion batteries are widely used as the power source for electric vehicles (EVs). Due to the temperature-sensitive nature of the performance of the Li-ion batteries, an effective battery thermal management system (BTMS) is critical. In this paper, a refrigerant-based BTMS is proposed, which could heat and cool the battery pack without auxiliary systems. Experimental comparisons between the proposed refrigerant-based BTMS and a coolant-based BTMS are performed in terms of the system dynamic response, thermal characteristics, and energy consumption, under a wide range of ambient temperatures. The experimental results indicate that the proposed BTMS operates efficiently by controlling the pressure and the superheat of the refrigerant. Furthermore, the proposed BTMS is able to maintain the maximum battery cell temperature within 46 °C and maintain temperature uniformity with a maximum cell temperature difference below 5 °C. Compared to the coolant-based BTMS, the heating rate of battery with refrigerant-based BTMS is effectively improved 30.6% at an ambient temperature of −20 °C. Besides, the energy consumption of the refrigerant-based BTMS decreases by 40.4% and 56.8% under ambient temperatures of 38 °C and −20 °C, respectively.