Experimental investigating of electro-osmotic flow in effect of current and ‎humidity of inlet gases into the single PEM fuel cell‎

In this study, the relative humidity of the gases in the PEM fuel cell was changed and its effect on electro-osmotic flow was investigated. ýBy changing the humidity on both sides of the fuel cell and using the water balance equations, the values of the electro-osmotic flow, ýelectro-osmotic coefficient and net drag in different humidity levels were found. Results showed that variations of the electro-osmotic ýflow changed linearly by anode and cathode humidity to the special humidity and after that not much variation was seen. In addition, the ýresults revealed that humidity change at anode had more desirable effect than the cathode. For example, at 70% anode humidity and 35% ýcathode humidity with the current of 5A, the value of electro-osmotic flow was obtained as 2.66639E-06 mol/cm2.s, while in the former ýý35% and the latter 70% with the same current, this value was recorded as 2.56418E-06 mol/cm2.s. In addition, results showed that theýþ þvariations of the electro-osmotic coefficient changed linearly by humidity. It was determined the current change of fuel cell has not so ýeffect on the curves of electro-osmotic coefficient. The electro-osmotic coefficients varied between 0.636001 and 1.632476, which were ýin a good agreement with the values obtained in other related papers. In addition, the variations of the net drag in respect of humidity were ýinvestigated, too. It was determined that the net drag changed linearly by the cathode humidity with positive slope, but its variations by ýthe anode humidity were linearly with negative slope.ý