Because water accumulation in the a

Because water accumulation in the anode is a long and complicated process, the main purpose of this paper is to observe the purge process in the anode GFC, especially for the upflow under the given conditions. In order to accelerate the liquid water accumulation, the moist hydrogen is used. The relative humidity of the gas after passing the humidifier is 100%, which is indicated by the use of Vaisala’s HMP363 hygrometer. The relative operation conditions in Fig. 2 are described as follows: the cell temperature was controlled to be 50 ◦C, while the humidifiers were kept at 60 ◦C. Current densities used in this study were step-changed, from 0.2, 0.6, 0.8, 1.0, and 1.2 A cm−2 by turns, while the volume velocity of hydrogen was maintained at 96 sccm and the air velocity was 228 sccm. Thus, the corresponding hydrogen stoichiometric ratios were 15.1, 5.0, 3.8, 3.0 and 2.5 lasting for every 10 min. The response voltages were captured by Arbin instrument every 2 s (see Fig. 2(b)). The purge process, which had a sharp peak value, appeared under the above conditions. Comparing with the response voltages simultaneously, the effects of the water behavior on cell voltage were shown in Fig. 2(c).