Numerical Research on the Cold Start-up Strategy of a PEMFC Stack from-30℃

The cold start-up of the PEMFC(proton exchange membrane fuel cell)stack from sub-zero temperature is considered one of the significant obstacles to its expansive commercial applications.In the cold start-up process,with the progress of hydrogen/oxygen chemical reaction,the produced water will freeze into ice,occupying the pores of the porous electrode,thus leading to a rapid deterioration of output performance and even making the cold start-up fail.In this work,a one-dimensional numerical model is adopted to study a cold start-up process of the PMEFC stack starting from-30℃.The stepwise-changed current loading mode is employed in the process.An assisted preheating method is used to explore an optimal operating condition for a successful cold start-up.The numerical results are validated by comparing the numerical result with the experimental data in reference,and they agree with the experimental data very well.The results show that the optimal heating power in the studied range is 100 W.As the initial current slope increased,the current peak value increased,but the cold start-up process failed.Also,the start-up time and ice volume fraction are highly dependent on the initial current slope.The optimal initial current slope is 0.7 A/s.Besides,a higher initial current slope will cause a significant inner ohmic resistance.The resistance of CLa(catalyst layer of the anode)is the key and primary part of the total ohmic resistance.The details of the research and the analyzed results will help design the cold start-up strategy for the PEMFC stack start-up from-30℃.