2016, Volume 19, Issue 2
CFD Investigation of Gas Diffusion Layers Compression on the PEM Fuel Cell Performance
1 National Research and Development Institute for Cryogenics and Isotopic Technologies - ICSI Rm. Valcea, Uzinei Street no. 4, PO Box Râureni 7, 240050, Râmnicu Vâlcea, Romania
2 University of Sheffield, UK
A numerical investigation based on ANSYS Fluent software has been carried out in order to determine the effect of the clamping force used in assembling a proton exchange membrane (PEM) fuel cell on its overall performance. The assembly process has a strong influence on the gas diffusion layers GDL since its structure and properties (porosity, permeability, contact resistance) are modified by the pressure applied to seal the fuel cell. At the same time, the GDL may be further compressed by the membrane if this will swell due to excessively water forming and due to its fixed position between electrodes. These changes can affect the water transport, can lead to cell flooding, to fuel cell damage and consequently to a decrease in the performance. To investigate the effect of GDL compression and its intrusion into the channels two cases were considered: one with the uncompressed GDL and one with the compressed GDL (33% compression ratio).
The numerical results obtained have shown that the GDL compression and intrusion into the channels have a considerable influence on the transport characteristics inside the PEMFC, and consequently on its performance. An increase with 5% in terms of current density was obtained for the compressed case due to a better mass transport (a larger contact area and a smaller contact resistance between the gas diffusion layer and bipolar plate are obtained by compression). The influence of pressure and relative humidity was analyzed for both cases and it was found that by increasing the values of these parameters a better performance can be achieved. As the operating pressure is increased from atmospheric to 3 bars an increment of performance with 9% was obtained for the compressed case, while as increasing the relative humidity from 25% to 95% the increment in current density for the compressed case is only with 5.5 %, comparing with the uncompressed case.
Gas diffusion layer compression, numerical investigation, PEM fuel cell.
Tag search Gas diffusion layer compression numerical investigation PEM fuel cell