Visualisation study on water management of cathode dead-ended PEMFC under pressure-swing operation

Abstract

Dead-ended proton exchange membrane fuel cells (PEMFC) using pure hydrogen oxygen can improve fuel efficiency and simplify fuel cell systems have been wildly used for a closed space. But the dead-ended operation of the PEMFC will cause difficulties in water management, especially in the cathode side, resulting in deteriorating of fuel cell stability. For this reason, gravity assisted drainage method, static drainage method are designed to migrate the water out of the cell. However, even with these methods, the reliability of the water removing from the cell remains questionable. Therefore, this paper introduces a novel water removal method to solve these problems and visualisation techniques were used to a more comprehensive knowledge of water transport mechanisms in dead-ended PEMFCs. A pressure-swing operation is realized by controlling the inlet of PEMFC solenoid valve to remove water and recycle oxygen during purging. The dynamic response characteristics of this system under different current densities, pressure differences, cell temperature and purging intervals are experimentally investigated in detail. It found that the water removal rate of the cathode flow channel of dead-ended PEMFC was as high as 99.25 ​%, and the fuel utilisation of the cell was close to 100 ​% in this water management mode.