Investigation of purge time in cathodic dead-end mode PEMFC

 Recently, special type of fuel cells has been developed that operates in a Dead End mode. Working in this condition, the Dead-End fuel cell is supplied withhydrogen almost at the same rate of consumption. It is noteworthy to mention thatall of the water transport mechanisms have been considered in this simulation.Water accumulation that is directly proportional to the cell current is of a greatimportance and has a negative impact on the cell voltage and its performance.Hence, water and gas management in Dead-End mode should be handled properly.To do so, determining the suitable time of purge and its duration is valuable with adirect impact on cell performance. In this paper, the channel and gas diffusion layerhave been considered as a single control volume and the blockage effect has beeninvestigated by means of thermodynamic analysis. In order to obtain a reasonableassumption, we have studied three different scenarios: GDL flooding, channelflooding and GDL-channel flooding simultaneously. The influence of blockageeffect rate of gas diffusion layer and channel on cell voltage drop, performance andpurge time have been studied. Voltage drop curves in different operating conditionshave been presented and the results show an acceptable agreement withexperimental studies. These curves have been investigated for different currentdensities (0.5, 1 and 1.5 A/cm2), active areas (25, 50 and 100 cm2) andtemperatures (60-80 °C).An Increase in temperature and in current density, reducespurge time interval, while increasing active area has an inverse impact. In highcurrent densities, the effect of temperature variation can be neglected.