THE FLOW AND COMPONENT VARIATION CHARACTERISTICS OF THE HYDROGEN SUPPLY SYSTEM IN FUEL CELLS

Nitrogen gas on the cathode side of the fuel cell permeates to the anode and accumulates due to the concentration gradient, reducing the hydrogen concentration and leading to localized fuel starvation at the anode. The hydrogen, nitrogen, and water vapor concentrations, as well as the flow rate in the hydrogen circulation loop, can be monitored online using ultrasonic sensors. This study investigates the component variation in the anode circulation loop of the fuel cell system through experimental methods and analyzes its impact on output performance. The results show that as the current density increases, the water vapor concentration gradually increases. The hydrogen concentration at the anode remains between 70% and 75% across different current densities, while the nitrogen concentration remains around 20% to 25%. With the increase in current density, the time interval for opening the drainage valve gradually shortens, which is attributed to the increasing water production in the cell.