Experimental Evaluation of Purge Strategies in the Recirculation Path of a PEM Fuel Cell System

PEM fuel cell technology plays a vital role in realizing an emission-free mobility and, depending on the considered use case, offers significant advantages over battery electric solutions as well as hydrogen combustion engines. When high performance over a longer period of time as well as short refueling times are key requirements, fuel cell powertrains show their core strengths. However, the adaption of fuel cells in the mobility sector strongly depends on their efficiency which directly relates to the vehicle’s fuel consumption, range and ultimately cost to operate. Therefore, the influence on efficiency and power of different purge strategies used to operate PEM fuel cells is experimentally investigated and compared. A concentration-dependent purge strategy is developed and examined in reference to a charge-dependent strategy. The measurements are carried out on a fuel cell system test bench which corresponds to a fully functional fuel cell system including all commonly used peripheral components. In the range investigated, both purge strategies show similar values regarding the analyzed utilization coefficients and power. However, for the maximum fuel cell current examined, the concentration-dependent purge strategy achieved slightly higher utilization coefficients while showing a minimally lower power output. Taking this into account, further research regarding the optimization of concentration-dependent purge strategies appears promising. For the time being, the decision between using a charge-dependent or a concentration-dependent purge strategy foremost relies on the presence of a suitable hydrogen concentration sensor.