Three-dimensional simulation of a proton exchange membrane fuel cell with non-integrated metal foam as flow distributor

Abstract

In proton exchange membrane fuel cells (PEMFCs), the presence of metal foam in the flow channels improves the polarity diagram and increases the cell generated power, but this leads to an increase in pressure drop and, as a result, an increase in parasitic power. In this study, two types of non-integrated arrangements of metal foam are introduced, which, in addition to having high generated power, have lower pressure drop, and subsequently, lower parasitic power, and will also result in a more uniform distribution of temperature and current density. In the first arrangement, which is called IPTG, an abbreviation of Increased Porosity Toward the gas diffusion layer (GDL), the channels are divided into four equal parts with variable porosities from 0.65 to 0.95, in such a way that the metal foam layer with the highest porosity (0.95) is located in the closest area to the GDL. In the second arrangement which is called Reduced Porosity Toward the GDL, the metal foam layer with the least porosity (0.65) is located in the closest area to the GDL. To make a better comparison between the present model and the conventional one, the net power parameter with subtracting parasitic power from generated electrical power of the fuel cell is calculated for all models. The numerical study of this paper is conducted by developing a three-dimensional computational fluid dynamics model by employing user-defined functions. The results show that the net power of the PEMFC with IPTG arrangement is 3.8 % higher than that of the one with integrated metal foam arrangement with a porosity of 0.95. Also, the higher the pores per inch (PPI) of metal foam used in the non-integrated metal foam model, the greater the net power of the fuel cell, so that, the net power of PEMFC with IPTG arrangement with PPI=80 is 3.2 % more than that of PPI=20.