(293b) Cathode Filtration System Design and Optimization for PEM Fuel Cells

Cathode contamination causes significant performance degradation of proton exchange membrane fuel cells, as a result of poisoning the membrane electrode assembly. Since the variety of contaminant species, the simplest solution to mitigate the contamination effect is using cathode filtration. However, the cathode filtration increases the parasitic power loss and hence reduces the net power output of fuel cells. Typically, the total system parasitic losses can reach up to 10-20% of net power output depending on the system design and optimization. This study aims to maximize the net power output and life-time of fuel cells in a polluted air environment by using novel filter media and optimizing the filtration design. A novel adsorptive sorbent media, activated carbon fiber enhanced microfibrous entrapped sorbent was developed and used as a polishing layer to improve the performance of traditional packed bed filter. The full size activated carbon filter (24×24") was tested in a full scale test rig which was constructed according to ANSI/ASHRAE Standard 145.2. The resulting breakthrough data was applied to determine the adsorptive filter parameters including the saturation capacity and adsorption rate constant. At last, a filter design methodology was developed through carefully considering the attributes of fuel cell, operating conditions (air flow rate, stoichiometric ratio, operating temperature and pressure, current density, etc.), and polluted air properties (contaminants types and concentration). The design methodology was successfully applied to a 60 kW fuel cell to simulate the relationships between net output and filtration with time. The simulation results show that the optimization of filtration design can significantly reduce the power consumption of compressor and hence improve the total efficiency of fuel cell system.