The real time dynamic water transport investigation due to net water transport coefficient (NWTC) based on measurement of water content in the outlet gas in a PEFC

The present method is expanded from the previous research [1], based on the experimental water pressure in the anode and cathode outlet. The real time NWTC in cathode and anode are obtained. The general NWTC, the peak NWTC, and the average NWTC in start-up and shut-down are discussed. The results show that, firstly, the membrane absorbs water from cathode and anode in the start-up after the current turned on and discharges water to cathode and anode after the current turned off, which causes the dynamic NWTC far from the steady state value. Secondly, there is peak value for NWTC both for start-up and shut-down, the anode peak value is nearly independent on the current in start-up, and decreases (more water transport) with increase of the current in shut-down. The asynchronous appearance moment of the peak values in the cathode side and the anode side are obtained. The average NWTC in the time interval of start-up keeps the same trend as the steady NWTC with increase of the current in start-up, and more water is discharged from the membrane for high current in shut-down.