An Experimental Study on the Cooling Performance of Capillary Driven Evaporative Cooling for Cylindrical Cells

Abstract

Capillary driven evaporative cooling (CDEC) is a novel concept that can directly wet-cool the surface of the battery through evaporative cooling. In this study an experimental setup was developed to establish the applicability of CDEC in cylindrical cells and to test its cooling performance compared to other battery thermal management systems. The test rig was designed using emulated cylindrical cells to test the performance of the cooling system using SF33 and Novec 7000 as working fluids. Results revealed that both working fluids were capable of maintaining the cell temperature within acceptable temperature limits. For a constant heat load of 10W per cell (531kW/m3) it was found that the cell average temperature can be maintained below 40 ℃ with both SF33 and Novec 7000. Furthermore, it was found that CDEC can ideally maintain the temperature uniformity within 5 ℃ across the cells in a module. SF33 with its low specific heat capacity and low saturation temperature shows a faster response and high cooling rate compared to Novec 7000. It can be concluded that SF33 and Novec 7000 are promising working fluids for capillary driven evaporative cooling battery thermal management systems even though SF33 would be a better alternative to Novec 7000.

Keywords: Capillary drive, two-phase cooling, evaporative cooling, passive cooling