Research For The Effects Of Inlet Gas Humidification Efficiency On The Performance Of Vehicle Fuel Cell

In order to study the influence of inlet gas humidification on the performance of PEMFC,in this paper,two kinds of methods including simulation and experimental are conducted.Firstly,the inlet gas humidification efficiency(IGHE)model is proposed and the calculation is introduced.This model considers the relationship between the internal electro-migration water content and the external water content of the humidified inlet gas.A formula for IGHE is derived and the current density of PEMFC could be calculated by the parameters of inlet gas humidification and IGHE.Secondly,the schedule diagram of fuel cell calculation and calculation methods are given.Moreover,the simulation for fuel cell is conducted based on them.The geometric model is established according to actual size of PEMFC and the computational meshes are partitioned by using the software(Fluent).Furthermore,the experimental system working principle of PEMFC,the method of measurement,fuel cell testing equipment,experimental steps and experimental parameters of symmetrical humidification are given.The experiments are conducted at the fuel cell operating temperature of 70?,at 40% relative humidity(RH),55% RH,70% RH,85% RH and 100% RH,respectively(symmetrical humidification between anode and cathode).Finally,the results from the simulation and experimental are respectively compared and analyzed in detail through the polarization curves of experimental,IGHE model and Fluent model at 40% RH,55% RH,70% RH,85% RH and 100% RH(70? operating temperature)and contours of H O molar concentrations in anode channels,H O molar concentrations in cathode channels and PEM water content.The results show that with the increase of inlet gas RH of PEMFC,IGHE and the accuracy of the IGHE model are decreasing gradually.When the inlet gas RH are 40%,55%,70%,85% and 100%(70?operating temperature and 350 mA/cm current density),IGHE are 57%,52%,43%,36%,respectively.At the same time,the accuracies of IGHE model are improved by 79%,51%,25%,10% and 4% compared with Fluent model.When the inlet gas RH is 100%,the distributions of H O molar concentrations in anode channels,H O molar concentrations in cathode channels and PEM water content are the most uniform.It means that when the inlet gas RH is 100%,the performance of PEMFC is the best under these conditions.