Effect of humidification of reactive gases on the performance of a proton exchange membrane fuel cell

This work studies the impact of water formation on the performance of Proton Exchange Membrane Fuel Cells (PEMFCs). The work examines water management in PEM fuel cells both experimentally and theoretically. Experiments are conducted using a one stack PEM fuel cell fitted with Nafion membrane to evaluate its performance using both dry and humidified hydrogen and air. Results obtained confirms the importance of fuel humidification in improving the performance of the fuel cell with all levels of humidification producing better performance than that obtained using dry hydrogen or dry air. Experiments using air with 50% relative humidity indicate drop in the fuel cell performance when comparing the results to those from air with 100% relative humidity. The experimental data provides the basis to validate a computation fluid dynamics model for the fuel cell that is used to carry out further studies and conduct a parametric analysis of the fuel cell performance to examine the effects of flow plates designs, flow patterns such as parallel and counter flow and level of humidification on membrane water saturation, flooding, water management, reactants concentrations and overall cell performance by observing parameters such as membrane protonic conductivity, current density, cell voltage and power. The CFD model studies and compares the use of air and oxygen in PEM fuel cells and the results show that for 100% relative humidity the performance obtained using pure oxygen is only marginally better than the one obtained when using air. This indicates that it is more beneficial to use air at the right conditions in PEM fuel cells given the cost of pure oxygen as the overall economic balance and the ease of use favour the utilisation of air.