The performance analysis of a multi-duct proton exchange membrane fuel cell cathode

A 3-D numerical study was carried out first to analyze flow, heat and mass transfer as well as current distribution in a single half-cell cathode duct of a Proton Exchange Membrane (PEM) fuel cell. From practical point of view, it is necessary to put the appropriate number of cells in a stack. Hence, the above study on a single half-cell is extended to a multiple ducts. Due to multi-duct configuration the assumption of uniform flow distribution would no longer hold true. Therefore, the duct flow maldistribution is considered in the simulation of the multiple ducts. The flow arrangement of the PEM fuel cell resembles that of the plate heat exchangers. Hence, the various types of flow distributions pertinent to the plate heat exchangers are applied to the PEM fuel cell ducts and their effects on heat and mass transfer as well as current distribution are studied in detail. The water formed at the active surface due to the electrochemical reaction diffuses through the porous layer and eventually enters the gas flow duct. A high gas velocity removes the product water at a faster rate from the duct. In nominal-linear and hyperbolic flow distribution cases, the mass fraction of water in the duct is more than that in severe-linear and hyperbolic flow distribution cases. This means that the membrane retains higher water content in nominal distribution cases. This in turn results in higher membrane conductivity and lower ohmic loss. This is the reason for better performance for nominal maldistribution cases over the severe maldistribution cases.