Numerical Modeling of Heat Pipe for Use in PEM Fuel Cell Cooling

Heat management of fuel cell is necessary to maintain the cell temperature in an appropriate temperature range (60-80℃) and to make a uniform temperature distribution in the cell, because the temperature control has a significant impact on the performance, efficiency and life cycle of a polymer membrane fuel cell. One of the passive cooling methods is to use phase change process. The heat pipe facilitates a uniform temperature control of the cell without consumption of electric power. In this paper, a heat pipe for cooling a low-power 200-watt fuel cell is proposed, and the two-phase and transient flow of a heat pipe with water as working fluid is modeled. In order to investigate the performance of the heat pipe, the volume of fluid model and the porous medium model have been used. Simultaneous modeling of evaporation and condensation processes in the heat pipe is performed using a user defined function in the ANSYS Fluent software. The results show that utilization of thermal pipe leads to maintain the temperature of the evaporator section at 69℃, which is equal to the temperature of the bipolar plates of the cell, and it is in the appropriate range of the operating temperature. In fact, the heat pipe is able to dissipate the heat of the cell properly and to maintain a relatively uniform temperature distribution inside the cell, simultaneously. The low values calculated for the thermal resistance of the heat pipe indicate an improvement in the performance of the fuel cell cooling system.