This type of water transport is a r

This type of water transport is a result of the excess water generated at the cathode region which diffuses back to the anode region. Water diffuses back from the cathode along the membrane empty space as result of water concentration gradients in the fuelcell [45,46] and research activity on BD from the cathode region to the anode region has attracted considerable interest recently. In addition to water concentration gradient, membrane thickness and pressure gradient through the membrane are among the otherfactors that determine the BD coefficient [47]. Experimental studies have also been conducted to measure the back diffusion coefficient of water [48]. The earlier research conducted showed huge differences between the measured values [48] and the discrepancieswere attributed to the applied measurement techniques according to Majsztrik et al. [48] who concluded that the various methods used measured different rate processes. Majsztrik et al. also accounted for the swelling of the membrane and their work was further developed by Paul et al. [49] who emphasised the importance of the kinetics of sorption and desorption and their effect on water activity and temperature.