Effects of micro heat pipe arrays on thermal management performance enhancement of cylindrical lithium‐ion battery cells

The performance of lithium-ion (Li-ion) batteries in a battery module is significantly affected by the operating temperature. Temperatures above 40°C can speed up the battery aging and shorten the lifespan and may even lead to thermal runaway. Besides, the maximum temperature deviation between the cells inside the battery module is normally expected to be less than 5°C. Among various cooling strategies used in thermal management of Li-ion batteries, application of micro heat pipe arrays (MHPAs) has received little attention. Hence, in the present study, a feasibility study has been conducted to assess the thermal performance of such a thermal link in controlling both the maximum temperature and temperature dispersion within the desired range. The MHPA-assisted cooling system was tested under various rates of heat generations (10-25 W total) and degrees of inclination (−90° to +90°). Experimental results have revealed a significant influence of the MHPA angle of inclination on the temperature of the evaporating section of the heat pipe. The best thermal performance was found to be at an angle of inclination of −15° where the condenser is located above the evaporating section. Performance degradation was observed for all the MHPA orientations where the condenser is located below the evaporating section. The thermal performance of the MHPA-assisted cooling system is also influenced by the rate of generated heat. The maximum effective thermal conductivity for the MHPA was measured to be about 75 000 W/m2 °C. A dimensional figure of merit is defined for the MHPA-assisted cooling system.