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Coolant Induced Variable Temperature Flow Field for Improved Performance of Proton Exchange Membrane Fuel Cell

Proton exchange membrane (PEM) fuel cell efficiency is dependent on water and heat management of the cell. In order to achieve high performance, the membrane hydration must be high. Common practice of maintaining isothermal temperature profile along the flow field of the cell requires external humidification in order to achieve high membrane water content. This thesis presents the concept of the variable temperature flow field for high performance PEM fuel cell operation without the requirement for external humidification. Internally generated water and heat are used for maintaining relative humidity of the reactants close to 100% along the entire flow field. The desired temperature profile is achieved by gradually increasing the temperature of the coolant during the passage through the PEM fuel cell. The concept is applicable for PEM fuel cell stacks for the first time. Computational fluid dynamics models of a single cell and five-cell stack were developed in order to investigate the concept. The models were calibrated and thoroughly validated on the newly developed experimental setup with very high level of agreement in all aspects. The results have shown that the PEM fuel cell operated with dry reactants, with applied variable temperature flow field concept, shows superior performance when compared to conventional fully humidified isothermal operation.

PEM fuel cell ; Computational Fluid Dynamics ; Segmented PEM fuel cell ; Variable temperature flow field

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