Thermal performance of aluminum vapor chamber for EV battery thermal management

Abstract

An aluminum vapor chamber for the thermal management of a rectangular battery cell was fabricated, and its thermal performance was thoroughly investigated according to the working fluid, cooling plate placement, and filling ratio. The heat-generation from the battery cell was simulated using a flexible surface heater with the size of 90 × 90 mm2, and the heat transfer rate was varied from 2 to 40 W. The vapor chamber with the size of 138 × 90 mm2 comprised two aluminum plates with the thickness of 2.5 and 1.5 mm, respectively. One plate has a porous layer with a thickness of 500 μm inside, and the other has a grooved channel with the depths of 1.0 and 1.5 mm for the flow passage of the vapor. The aluminum vapor chamber using acetone as working fluid showed better thermal performance than that using HFE-7100, owing to the superior wicking capability. The vapor chamber showed the best performance at the filling ratio of 25%, irrespective of the heat transfer rate. At the low filling ratio of 10%, the vapor chamber exhibited a partial dry-out as the heat transfer rate increases. At the high filling ratio of 66%, the thermal performance was much degraded owing to the reduction of the active area involved in the evaporative heat transfer. The thermal performance of the vapor chamber was compared with a solid aluminum plate using an actual lithium-ion battery cell, where the temperature increase of the cell employing the vapor chamber was reduced by 41% and 61% during charging and discharging processes, respectively.