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A good water management is very important for the operation of PEM fuel cell systems as the proton conductivity is dependent on the membrane water content. In contrast to state of the art approaches, this study focuses on an anode based water management approach of fuel cell systems with an anode recirculation loop. The aim of the anode based water management is to reach a high and homogeneously distributed anode humidity without condensation in all relevant operating conditions. A criterion is defined to evaluate the anode humidity distribution. A macroscopic discrete 2D+1D model was developed that can simulate humidity distributions and the cell voltage for various flow directions of the fluids and operating conditions. The model considers the system behavior including the anode recirculation loop. This study shows that flow directions that support an internal water circulation are beneficial for fuel cell systems without external humidification. Furthermore, the study shows a correlation between the anode humidity distribution at the membrane and the cell voltage. The higher the temperature is, the more important is a flow field that supports a high and homogeneously distributed anode humidity. • Homogeneity of anode humidity is a good criterion for water management evaluation. • The system behavior has to be considered for the optimization of flow directions. • High and homogeneously distributed anode humidity results in high cell voltage. • Internal water circulation is important for fuel cell systems without humidifier. • High temperature operation requires supportive flow directions of the fluids. [ABSTRACT FROM AUTHOR]