A hybrid battery thermal management system for electric vehicles under dynamic working conditions

Lithium-ion batteries have been widely used to propel electric vehicles (EVs) owing to their high energy density, long lifespan, and high stability. However, the inevitable battery heat generation, particularly when there is a rapid increase in power under dynamic working conditions, threatens the safety and performance of EVs. In this study, we develop a hybrid battery thermal management system incorporating micro heat pipe arrays, convective air, and intermittent spray water. The heat pipes siphon the heat from the inside of the battery pack to the outside, and convective air dissipates heat during the normal operation of the EVs, while further cooling is achieved via intermittent spray water at high-power operations. For a 75 Ah lithium-ion battery pack under dynamic working conditions, the proposed hybrid system enables the maximum temperature to be reduced to 29.6 degrees C and the temperature non-uniformity to be 1.6 degrees C, which are 21% and 57% lower than those of thermal management systems without water spraying functions, respectively. Additionally, the energy consumption of the hybrid thermal management system is 4.9 Wh, only accounting for 1.8% of the total battery pack power capacity. Given these advantages, it is expected that the proposed thermal management system is a promising tool to address the practical thermal problems of lithium-ion battery packs used in EVs. (C) 2020 Elsevier Ltd. All rights reserved.