Fuel cell performance is strongly influenced by operating conditions such as pressure, temperature, reactant mass flow rate, and humidity. In fuel cell systems, auxiliary components such as the air compressor may consume a significant fraction of the power generated by the stack. Consequently, determining the operating parameters that maximize the system efficiency is a key challenge in fuel cell system design. However, most fuel cell models used at the system level are overly simplified and do not adequately capture voltage variations induced by changes in operating conditions. In particular, humidity distribution inside the cell strongly affects the membrane conductivity, yet these impacts are often poorly represented in simplified models.

This work presents a fuel cell model that is sufficiently detailed to capture the main physical phenomena associated with the operating condition variations while remaining computationally efficient for integration into system-level simulations. A semi-two-dimensional model is developed to capture the effects of the variations across the different layers of the cell and along the flow direction. The model is integrated into a system architecture including anode recirculation and operates without external humidification at the cathode.

This model enables to determine the water transport and humidity distribution, allowing improved estimation of ohmic losses. Simulations show that operating parameters mainly affect cell voltage through their influence on ohmic losses. Controlling pressure and temperature is therefore critical to maintaining appropriate humidity levels within the cell. Furthermore, the results highlight that temperature gradients along the flow direction and anode mass flow rate from recirculation significantly affect relative humidity distribution. The spatial homogeneity of water content directly influences current distribution and, consequently, both the efficiency and durability of the fuel cell.