The objective of this study is to calculate the MacMullin Number (NM) of various Gas Diffusion Media to improve understanding of the transport through the Gas Diffusion Layer (GDL) for the Electrochemical Fuel Cell Model. In this model, GDL’s are used in the electrolyzer and the fuel cell itself. The outcome of this work will allow for different GDL’s to be compared to each other in a way that the best fit for the Fuel Cell Model can be determined. Experimental data obtained through the Conductivity Cell will allows for the NM to be calculated. The GDL materials used are activated carbon, nickel foam, and nickel mesh. Some samples have the addition of a microporous layer (MPL) to improve transport. A NM calculation allows for the samples with and with out the MPL to be compared. Once an average NM was found for each sample, the data was plotted and a trendline was fit. The trendline was used to compare NM calculation data to previous experimental data. The primary focus of the experiment is the comparison the porosity of the GDL samples verse the calculated MacMullin Number for each sample.

Figure 1 shows the Porosity of various GDL’s plotted against the calculated MacMullin Number. In this figure, GDL’s with an MPL and without an MPL were plotted and the trendline through the data was compared to the Bruggeman equation and the Toray equation. GDL’s containing a MPL tended to have higher NM then the other samples. This happens because the addition of the MPL increases the resistance of the sample. Figure 1 allows for the prediction of different GDL samples NM by using the calculated porosity.

References:

1. Martinez, Michael J., et al. Measurement of MacMullin Numbers for PEMFC Gas-Diffusion Media. Journal of The Electrochemical Society, 2008, Measurement of MacMullin Numbers for PEMFC Gas-Diffusion Media.
2. Shimpalee, Sirivatch, et al. Experimental Investigation and Numerical Determination of Custom Gas Diffusion Layers on PEMFC Performance. Elsevier B.V., 2016, Experimental Investigation and Numerical Determination of Custom Gas Diffusion Layers on PEMFC Performance
3. Martinez, Michael J., et al. Effect of Microporous Layer on MacMullin Number of Carbon Paper Gas Diffusion Layer. Elsevier B.V., 2012, Effect of Microporous Layer on MacMullin Number of Carbon Paper Gas Diffusion Layer.