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, depend-ing 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 refuelling 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-dependant purge strategy is developed and examined in reference to a charge-dependant strategy. The concentration-dependent purge strategy manages the purge process based on the measured hydrogen concentration in the anode recirculation path. The charge-dependent purge strategy controls the purge process according to the amount of elec-trical charge converted by the fuel cell. Using a factorial design of experiment, the two purge strategies are compared in terms of electrical efficiency, fuel efficiency and the electrical power generated. The examination focuses on what efficiencies can be achieved with each of the two purge strategies and how they compare. 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. The concentration-dependant purge strategy is newly implemented into the test bench. The charge-dependant purge strategy resembles the default approach used to manage the purge process on the test bench.