Optimization of purge strategy under fuel cell startup conditions based on CFD-Simulink collaborative simulation

In order to reveal the effect of purging water during the startup process of fuel cells and optimize the purging strategy, a three-dimensional model and a one-dimensional model for the startup process of proton exchange membrane fuel cells (PEMFCs) were established. The influence of hydrogen flow rate and initial oxygen content was explored. The results show that at the beginning, the anode is filled with oxygen, but when hydrogen gas is introduced, the air is expelled along with the movement of the hydrogen-air interface. Once the anode is filled with hydrogen gas, the hydrogen-air interface disappears. As the flow rate increases, the residual oxygen content decreases more rapidly, and the time required to remove oxygen completely becomes significantly shorter. The higher the initial oxygen content, the longer the purging process takes and the more time is required for purging. As purging progresses, the rate of oxygen removal gradually decreases until it reaches zero. Using a high flow rate followed by a low flow rate for purging yields better purging efficiency, shorter purging time, and lower consumption compared to using a low flow rate followed by a high flow rate for purging. Implementing a stepwise or linear load increase during startup is beneficial for improving the voltage dynamic response and enhancing gas distribution in fuel cells.