Dynamic response study of air-cooled proton exchange membrane fuel cell stack

The dynamic response is a critical performance indicator of air-cooled fuel cells, directly affecting their operation's stability and reliability. This paper experimentally investigated the impact of different operating conditions on the dynamic response characteristics of the air-cooled proton exchange membrane fuel cell(PEMFC) stack. The overvoltage of fuel cells at higher ambient temperatures is smaller after loading, and it takes a shorter time for fuel cells to recover to a stable level. Different air supply modes were investigated, results show that increasing the cathode gas flow rate helps reduce the overshoot voltage of the air-cooled PEMFC stack. A higher cathode flow rate enhances the oxygen concentration at the catalyst layer, helping to supplement the local gas shortage. In addition, as the gas pressure inside the stack is slightly lower than the ambient pressure when the air-cooled PEMFC operates with the exhaust mode, the overshoot voltage of the exhaust air supply mode is 15.8 %higher than that of the blow airflow mode under the same air fan speed(4500r/min). Increasing the load change rate leads to insufficient local gas supply without enough time to replenish, causing the cell's overshoot voltage to rise; the more significant the load change rate, the greater the cell's overshoot voltage. Reducing the anode pulse purging interval can reduce the cell output voltage fluctuation with limited effect.