BUBBLE COLUMN EVAPORATIVE COOLING FOR PEMFC THERMAL MANAGEMENT IN HEAVY-DUTY VEHICLES

Paper i proceeding, 2025

Proton exchange membrane fuel cells (PEMFC) are a promising solution for heavy-duty transport due to their high efficiency and power density. Cooling of PEMFCs is challenging due to the low temperature difference between the PEMFC operating temperature and the ambient air. Typical heat loads are as high as the electrical power output and therefore significantly increased radiator dimensions are required which makes alternative cooling methods desirable. The electrochemical conversion of hydrogen into electricity produces water which can be collected from the FC exhaust stream. This enables the utilization of the high latent heat of water to reject heat. Previous literature investigations of bubble column desalination and humidifier systems suggest that high mass and heat transfer rates are possible. This offers an alternative way of evaporating the water compared to water spray on radiators. To realize a cooling system, first a heat exchanger transfers heat from the FC coolant to the product water. Then, the hot water is pumped to a bubble column in which the injection of FC exhaust air leads to evaporative cooling of the water. Afterwards, the cooled water is returned to the water storage tank and saturated exhaust air is vented. In addition, the solution functions as heat storage without increasing the vehicle's drag. We present the analysis of a novel bubble column evaporator with vehicle model results, compensating for the cooling limitations of a conventional FC heavy-duty truck cooling system at full FC load for up to 58 minutes at 20 and 35°C ambient temperature. A proof-of-concept testbench is planned for validation of the developed system.