Development of a fuel cell humidification system and dynamic control of humidity

Abstract

Summary Maintaining proper membrane humidity is essential for ensuring the optimal operation and durability of polymer electrolyte membrane fuel cells (also known as proton exchange membrane fuel cells). Conventional humidification systems have insufficient humidification capacities and slow humidity responses, and they can no longer meet the humidification needs of high‐power fuel cell systems. This study focuses on a high‐power fuel cell air humidification system. The humidification system uses a mixture of dry and wet air to enable rapid achievement of the inlet gas humidification requirements of the fuel cell. A complete model of the air humidification system is developed, and a proportional‐integral‐derivative controller is used to provide feedback control of the temperature and humidity in the humidification system. The results show that the overall relative humidity (RH) output of the humidification system exhibits high‐accuracy tracking of the RH demand under different operating conditions, without large oscillations. Meanwhile, the temperature of the mixing heater remains consistent with the temperature of the fuel cell stack. The trend for the wet air flow rate is basically identical to the change in the RH, and the change in the heating power of the mixer heater is almost the same as the change in the dry air flow rate. In addition, under the same humidification demand, the humidity regulation of this system at different operating powers has a better anti‐interference ability, and the maximum RH deviation is 8%. The results of the study can provide guidance for the optimal operation of existing high‐power fuel cell humidification systems.

Challenges in practical button cell testing for hydrogen production from high temperature electrolysis of water

“…Bubblers are technically simple and are much safer (Eder et al, 2022). The drawback of bubblers is that they are slow to change conditions when ramping or cooling to a temperature/water vapor concentration setpoint and the actual relative humidity versus the bubbler setpoint can vary by ~5% (Liu and Sharqawy, 2016;Fang et al, 2022). Bubblers require several minutes to reach steady state when ramping or cooling to a setpoint (Fang et al, 2022).…”

“…The drawback of bubblers is that they are slow to change conditions when ramping or cooling to a temperature/water vapor concentration setpoint and the actual relative humidity versus the bubbler setpoint can vary by ~5% (Liu and Sharqawy, 2016;Fang et al, 2022). Bubblers require several minutes to reach steady state when ramping or cooling to a setpoint (Fang et al, 2022). Bubblers control the water vapor concentration by varying water temperature which is directly proportional to its vapor pressure.…”