Mohammad Erfan Maleki, Mohammad Javad Keikhaei, Mahbod Moein Jahromi, Mohammad Jafar Kermani,
Volume 24, Issue 6 (5-2024)
Abstract
Recently, in many fuel cell applications, foam is being used as a flow distributor to increase efficiency and achieve a more uniform distribution of reactants on the active surface. However, despite the improvement in the efficiency and performance of the fuel cell, this method does not fully achieve the desired uniformity in reactant distribution. Therefore, in this study, non-uniform porosity metal foam has been utilized to improve the homogeneous flow distribution on the cathode side of the PEM fuel cell. At first, the foam is assumed to be uniform with the same porosity. After the numerical solution of the flow in homogeneous foam (first type), Two types of foam with variable porosity coefficient have been designed. These foams are divided into checkerboard shape, where the porosity coefficients in the concave corners (dead areas) with low molar fraction of oxygen are higher. This facilitates easier movement of the flow towards these corners, resulting in a more uniform flow distribution. the simulation results indicate that, for a constant current density, the distribution of the mole fraction of oxygen in both types of foam with a variable porosity coefficient has become more uniform. Additionally, the average molar fraction of oxygen has increased by 9.45% in the second type of foam and by 32.02% in the third type of foam compared to the uniform foam, which indicates an increase in generated power. Also, compared to the uniform foam, the pressure gradient in the foam with variable porosity of the second type increased by 75.80%, while it remained relatively unchanged for the third type foam.
