Experimental Study on a 1000W Dead-End H2/O2 PEM Fuel Cell Stack with Cascade Type for Improving Fuel Utilization

Proton exchange membrane fuel cells (PEMFCs) with a dead-ended anode and cathode can obtain high hydrogen and oxygen utilization by a comparatively simple system. Nevertheless, the accumulation of the water in the anode and cathode channels might cause a local fuel starvation degrading the performance and durability of PEMFCs. In this study, a brand new design for a polymer electrolyte membrane (PEM) fuel-cell stack is presented which can achieve higher fuel utilization without using hydrogen and oxygen recirculation devices such as hydrogen pumps or ejectors that consume parasitic power and require additional control schemes. In this manuscript the basic concept of the proposed design is presented. Concept of the proposed design is to divide the cells of a stack into several stages by conducting the outlet gas of each stage to a separator and reentering it into the next stage in a multistage construction of anode and cathode electrodes. In this design, a higher gaseous flow rate is maintained at the outlet of the cells, even under dead-end conditions resulting in a reduced purge-gas emissions by avoiding the accumulation of liquid water in the cells. Moreover, fluctuation of voltage in hydrogen and oxygen cells at dead-end mode is investigated. Furthermore the utilization factor of hydrogen and oxygen at different power is presented. Overall, the result shows that the proposed design has the same polarization curve as open-end mode one, resulting in a higher PEMFC performance.