Abstract
In proton-exchange membrane fuel cells, the air supply system provides desired air characteristics for the fuel cell stack, significantly affecting stack performance. This study analyzes the system by modeling and simulation responses under dynamic operating conditions. The model includes a compressor, a cooler, and an external humidifier in a series. Different air mass flow rates that represent demand changes were simulated in the compressor model, including extreme conditions under compressor surge. Then, the air temperature was reduced in the cooler by exchanging heat to coolant flow before reaching the humidifier. Lastly, the humidification model presents heat and mass transfer between wet air from the cathode exhaust to the supply air through a bundle of membranes. Simulation results were observed in MATLAB/Simulink, which predicted the changes in supply air characteristics and effects of load changes to the system. Higher load requires more flow rate and higher compressor speed, leading to lower water content in the cathode air. Due to low flow rate and high pressure, a compressor surge could cause an unstable cathode air supply.
