Performance evaluation of hybrid oscillating heat pipe with carbon nanotube nanofluids for electric vehicle battery cooling

The development of highly-efficient, cost-effective and reliable cooling schemes of electric vehicle (EV) battery is still an urgent need for the massive commercialization of EVs. In this paper, a hybrid oscillating heat pipe (OHP) fabricated by a copper flat-plate evaporator with parallel circular channels side and a capillary copper-tube condenser has been developed to remove the heat generated by EVs battery for its safe operation during rapid charging/discharging process. The ethanol aqueous solutions of carbon nanotubes (CNTs) (or CNT nanofluids) were selected as working fluids at a volumetric filling ratio of 35%. The volume ratio of water-ethanol mixture is 1:1, and the mass concentration of CNTs varies in the range of 0.05 wt% to 0.5 wt%. Experimental results show that the vertical OHP charged with CNT nanofluids exhibited better start-up and heat transfer performance as compared with that of ethanol-water mixture. At the CNT concentration of 0.2 wt%, the average evaporator temperature and thermal resistance of the OHP could be reduced to 43.1 degrees C and 0.066 degrees C/W, respectively, at 56 W power input, which are 9.8 degrees C and 0.278 degrees C/W lower respectively than that of ethanol-water mixture. Correspondingly, the average temperature and maximum temperature difference of the battery pack could be maintained below 45 degrees C and 1 degrees C, respectively. The hybrid OHP charged with water-ethanol mixture-based CNT nanofluids provides a promising option for EV battery cooling.

Automated summary

This study developed a hybrid oscillating heat pipe using CNT nanofluids for cooling electric vehicle batteries, demonstrating improved heat transfer performance and reduced battery pack temperature.