Decoupling strategy for react-air supply and cooling of open-cathode proton exchange membrane fuel cell stack considering real-time membrane resistance estimation

Abstract

Open-cathode proton exchange membrane fuel cells are widely used in portable power and unmanned aircraft because of their portability and simple structure. To address the mismatch between gas supply and hydrothermal management resulting from the direct utilization of ambient air as both oxidant and coolant, this study proposes a decoupling strategy for the react-air supply and cooling based on a stack coupled with vapor chambers. Additionally, extended Kalman filter is utilized to estimate the change of proton exchange membrane internal resistance in real-time under varying operating conditions. Experiments show that the membrane internal resistance rises by 0.061 mΩ and stack voltage drops by 0.31V during the increase of react-air flow rate from 0.244 × 10−2 m3/s to 0.470 × 10−2 m3/s with a constant loading current of 30A operation before decoupling. Decoupling react-air supply from cooling effectively mitigates membrane dehydration, reducing internal resistance by 0.023 mΩ and improving performance by 5.41% at 35A compared to before decoupling. Furthermore, results indicate that increasing react-air and cooling-air flow rates under high loading currents can improve stack temperature uniformity and performance consistency but reduce system efficiency. The optimal react-air flow rate needs to balance stack heat dissipation and the increase in internal resistance caused by membrane dehydration.