Dynamic Simulation of a Proton Exchange Membrane Fuel Cell System For Automotive Applications

A dynamic model of the PEMFC system is developed to investigate the behaviour and transient response of the fuel cell system for automotive applications. The system accounts for the fuel cell stack with coolant, humidifier, heat exchangers and pumps. Governing equations for fuel cell and humidifier are implemented into the code and are based on adopted mathematical models describing the voltages and current densities and their dependence on operating pressures, temperatures and stoichiometric ratios of the reactant gases.

As a result, this model can predict both steady and transient states. The model parameters have been adjusted specifically for a 21.2 kW Ballard stack [1]. This model also incorporates the effects of water cross-over in the fuel cell membrane. Controls for temperatures, pressures, reactant stoichiometry and flows are implemented to simulate the system behaviour for different loads and operating conditions.

Simulation results for system start-up and variable loads are discussed. Results for system efficiency, auxiliary power consumption, feed flow effects and water crossover are presented. Transitory effects of liquid water saturation at cathode are also determined. This study can provide sufficient insight for further in-depth analysis of PEMFC and prove to be a basis for efficient control and design methodologies.