Experimental study on the thermal management of an open-cathode air-cooled proton exchange membrane fuel cell stack with ultra-thin metal bipolar plates

Abstract

Reliable thermal management ensures stable and efficient operation of proton exchange membrane (PEM) fuel cells. An air-cooled fuel cell stack with metal bipolar plates was developed, and 32 micro-thermocouples were arranged for in situ measurement of the temperature distribution. The resistance characteristic of the stack was tested in a wind tunnel, and then the effects of hydrogen pressure and airflow rate were analyzed. The results show that the highest and average temperatures in the stack exhibit a “parabolic” distribution as well as the maximum temperature difference of each single cell on the inlet side of the cathode. However, the temperature difference on the outlet side shows an “anti-parabolic” distribution. With a decrease in the airflow rate, the temperature uniformity in the stack deteriorates gradually. When the maximum pulse width modulation (PWM) duty cycle of the fans was 70% and the current density was 500 mA/cm2, the temperature difference between different single cells and inside a single cell can reach 19.7 °C and 8.4 °C, respectively. The temperature uniformity in the stack at high current densities could be effectively improved by increasing the airflow rate. In addition, the hydrogen pressure and airflow rate have a certain effect on the voltage consistency.