Experimental Investigation of a Novel Design of Proton Exchange Membrane Fuel Cell Stack

Abstract

The results of a design study of a novel proton exchange membrane fuel cell (PEMFC) are presented in this paper. The need for alternative sustainable energy generation is growing as finite fossil fuel resources are gradually depleting. The PEMFC is particularly suited to the automotive and small scale stationary industries however at this stage fails to be a viable commercial alternative to the Internal Combustion Engine (ICE). The PEMFC has great potential but due to large material and manufacturing costs associated with components used in the fuel cell it has failed to make an impact on either of the industries mentioned above. A new design approach that removes the bi polar plate from the PEMFC stack is investigated. The bi polar plate is a multi functional component and also contributes significantly to the cost of the fuel cell stack. A single PEMFC, which features the design changes that can be integrated in the main stack, has been designed, manufactured, assembled and tested to obtain performance characteristics for a range of operating conditions. Two different flow configurations for the reactants i.e. dead end gas flow and through mode flow were tested. Dead end suffered largely from both Ohmic and concentration losses and resulted into poor performance. Testing also identified issues with the single cell design which included gas leakage and insufficient clamping pressure. Changes were made to resolve these problems and together with through flow gas mode 50% improvement in cell performance was achieved. The new design achieved performance comparable to that with conventional designs reported in literature. The experimental results confirmed that bipolar plate can be removed and it is possible to bring down the costs and weight of the stack drastically It is envisaged that the new design will allow the PEMFC to potentially inject into the current market. However, testing also highlighted the early signs of degradation on the metallic plates inside the cell. Gas starvation, varying load cycles and poor coating methods were believed to be responsible for the observed corrosion. These results contribute further to understanding of the performance, losses and related material degradation within a fuel cell and help modifying the stack design with mitigation strategies implemented to prevent further degradation occurring.