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A two-dimensional, steady-state and isothermal model of the proton electrolyte membrane (PEM) fuel cell has been developed numerically, using a commercial package COMSOL. The single channel cell, which consists of seven regions, is used as the computational domain. The governing equations for mass, momentum, mass transport and charge equations are coupled and solved to produce the polarization curves for the fuel cell performance. The resultant polarization curves obtained from the numerical simulation are validated by comparing with the experimental results under normal operating conditions. Further, the benchmarked numerical model is used to investigate the effect of the temperature, concentration of hydrogen, concentration of oxygen, operating pressure, stoichiometric flow ratio, channel height, gas diffusion layer (GDL) thickness, membrane thickness and GDL porosity on the performance of the PEM fuel cell. The modeling results agree reasonably well with the experimental polarization curves within allowable numerical scatter, except the mass transport region. As the fuel cell and the gas humidification temperature increases, the current density and maximum power density both increase. This trend is also observed in the concentration of hydrogen and the concentration of oxygen in air. As the concentration increases, the improvement of the fuel cell performance becomes negligible. The increase in operating pressure in both flow channels also increases both the current density and maximum power density. Between the two flow channel’s operating pressure, the cathode flow channel’s operating pressure plays a predominant role in affecting the performance of the fuel cell. As the stoichiometric flow ratio of hydrogen and air are increased at both flow channel inlets, the current density, the limiting current density and maximum power density increase. For the stoichiometric flow ratio of 5.0 and above, the improvement in the fuel cell performance is negligible. Further investigation shows that, the air stoichiometric flow ratio has a predominant effect in improving the performance of the fuel cell while the hydrogen stoichiometric flow ratio does not have any effect, based on the present simulation. As the channel height increases, the current density and the maximum power density increases. Above a particular height, i.e. 1mm, the improvement in the performance of the fuel i cell is negligible. The increase in thickness of both GDL, reduces the current density and maximum power density. The GDL thickness of cathode and anode have almost equal contribution towards the performance of the fuel cell. As the thickness of the membrane increases, the current density and the maximum power density reduces. By increasing the GDL porosity of both anode and cathode, the current density and the maximum power density will be increased. For the porosity of 0.5 and above, the improvement of current density and maximum power density are negligible. Further investigation on the effect of individual GDL porosity shows that the cathode GDL porosity has predominant effect in improving the performance of the fuel cell while the anode GDL porosity does not have any effect on the performance of the fuel cell. A sensitivity analysis has been conducted on the fuel cell operation, using analysis of variance (ANOVA), which is a statistical tool, used to determine how sensitive the parameters are. The factors are separated into two categories. For the operating parameters, the more sensitive factors that affects the fuel cell’s current density are the temperature of the fuel cell and the humidification of both hydrogen and air, the operating pressure of the cathode flow channel and the concentration of oxygen in air supplied to the cathode flow channel. While for the maximum power density, the more sensitive factors are the operating pressure of the cathode flow channel and the concentration of oxygen in air supplied to the cathode flow channel. The most sensitive factors among the design parameters in affecting the fuel cell’s current density and maximum power density are the membrane thickness, cathode GDL thickness and anode GDL thickness.

A parametric study of Proton Electrolyte Membrane (PEM) fuel cell performances