Numerical Simulation of Coolant Electrolysis in Composite Plate PEM Fuel Cell Stacks

Two- and three- dimensional numerical models of a PEM fuel cell have been developed to investigate the effects of shunt current within the coolant channel. The model accounts for the electrostatic equation solved for a ten cell fuel stack for idealized and realistic coolant channels including varying conductivities of the solution. The electrostatic equation was solved in the coolant channel for the fully insulated, non-insulated, and incremental lengths of insulation on the channels. The model results found that the length of the insulation on the coolant channel plays an important role in shunt current reduction and fuel cell performance. The case of insulating the coolant channels was found to show that current density propagated further into the channels as increased lengths of insulation were used. However, the strength of the current density from the ending point of the insulation was found to decrease with increasing insulation lengths. Furthermore, a simple experiment was conducted idealizing the fuel cell as batteries connected in series and then submerged in a low conductivity solution. A camera was used to capture the current potential in the different “stacks” and to validate the numerical model.