Development of Fuel Cell System Air Management Utilizing HIL Tools 2002-01-0409

In this paper, boosting strategies are investigated for part load operation of typical fuel-cell-systems. The optimal strategy can mainly be obtained by simulation.

The boosting strategy is one of the most essential parameters for design and operation of a fuel-cell-system. High pressure ratios enable high power densities, low size and weight. Simultaneously, the demands in humidification and water recovery for today's systems are reduced. But power consumption and design effort of the system increases strongly with the pressure level. Therefore, the main focus must be on the system efficiencies at part load. In addition, certain boundary conditions like the inlet temperature of the fuel-cell stack must be maintained. With high pressure levels the humidification of the intake air before, within or after the compressor is not sufficient to dissipate enough heat. Vaporization during the compression process shows efficiency advantages while the needs in heat dissipation decreases.

With the simulation tool MATLAB/SIMULINK, supplemented by detailed self-developed design tools for compressor and expander units and hardware-interfaces for hardware-in-the-loop simulations, fuel-cell-systems can be modeled, simulated and verified accurately. The access to a wide database from compressor and fuel cell test benches allows precise simulation results with adjustable model complexity.