|About the Book|
Fuel Cells are devices that generate electricity by electrochemically combining hydrogen and oxygen. Water management plays an important role in the durability and efficiency of a proton exchange membrane fuel cell (PEMFC). In this study, singleMoreFuel Cells are devices that generate electricity by electrochemically combining hydrogen and oxygen. Water management plays an important role in the durability and efficiency of a proton exchange membrane fuel cell (PEMFC). In this study, single cells are modeled as lumped models consisting of 15 interconnected segments, which are linked according to the flow field patterns of the anode and cathode but they are treated as individual lumped elements. Parameters of this model were calibrated based on neutron radiography experimental results obtained at the NIST Center for Neutron Research (NCNR). Three special single cells were designed for the purpose of detecting liquid water and water vapor simultaneously. The major difference between our design and traditional flow field designs is the fact the anode channels and cathode channels were shifted sideways, so that the anode and cathode channels do not overlap in the majority of the active areas. The liquid water is measured by using neutron radiography. The water vapor is measured by the twenty relative humidity sensors embedded in the anode and the cathode flow field plates.-The effects of relative humidity and stoichiometry of cathode inlet on relative humidity distribution in the channels and on water accumulation in the GDLs were investigated in this study. The liquid water accumulation at steady-state was calculated by using imaging mask techniques and least-squares method. It is demonstrated that liquid water tends to accumulates in the gas diffusion layers under the rib. Modeling results suggest that opposite flow direction improve the cell performance at low humidity conditions. Accordingly, this segmented model is useful in designing flow field patterns and comparing the influence of different flow field patterns before they are machined on the flow field plates. That reduces the cost of developing and designing a fuel cell.