Treffer: Study on bipolar plate materials and characterization for proton exchange membrane fuel cells

For the establishment of proton exchange membrane fuel cells (PEM fuel cells) into the commercial market environment, factors such as low-cost materials and production are essential. The bipolar plate is one of the important parts that determine the cost, weight and current produced by a PEM fuel cell. Metal bipolar plate materials are broadly considered a great replacement to the conventional graphite bipolar plate material. There is an ongoing work in UWS fuel cell research laboratory to design and develop an innovative PEM fuel cell. In this work, the effect of different metal bipolar plate materials such as Al, Cu and S.S. of a single PEM fuel cell was investigated using a serpentine channel and a novel open-pore cellular foam material (OPCFM) as flow channel. Also, carbon was used in coating both S.S. and Cu bipolar plate material using Direct Current (D.C.) sputtering deposition by PVD techniques to improve the corrosion resistance of the bipolar plates for PEM fuel cell; the results were compared with their bare substrates. Computational fluid dynamics (CFD) using ANSYS Fluent was used for the modelling and simulation. The analysis includes different operating conditions such as temperature, the mass fraction of hydrogen, oxygen and water are presented. The bipolar material for each simulation were compared. Furthermore, the experimental study for each bipolar plate material using serpentine and OPCFM was conducted and compared. The Al material showed the best result from the simulation with a maximum current density of 1.47A/cm2, while Cu and SS materials produced current density of 1.39A/cm2 and 1.36A/cm2, respectively. There was a comparison from the different operating pressures, from 1.5 to 2.5 bar with OPCFM flow channel. The experimental result showed that the highest current density generated was at 2.5 bar for Al; Cu and SS material at 1.53A/cm2, 1.46A/cm2 and 1.38A/cm2 respectively. The result shows that the overall performance of a PEM fuel cell increases with an increase in operating pressure. Al bipolar plate material offers the best overall performance as a result of the adsorption of the material with the reactants. The polarization curve for the five-stack polarization curve of Al bipolar plate material produced a voltage of 4.42V. The better performance of the coated substrate exhibited higher polarisation resistance, which is associated with good corrosion resistance. The coated Cu and SS yielded Rp values of 19.30 x 104 Ω.cm2 and 18.60 x 104 Ω.cm2 whereas Rp values of 14.20 x 104 Ω.cm2 and 11.12 x 104 Ω.cm2 were obtained for the bare Cu and SS, respectively. Also, the corrosion potential for coated Cu and SS is 16.61 and -38.5 mV respectively, which is higher than the uncoated Cu and S.S. (-284.5 and -726.4 mV). The coated substrates of Cu showed a high impedance value than coated SS and uncoated substrates. However, the effect of the coating is highly significant; this is because the coated S.S. was able to outperform the uncoated Cu and SS. The results show that more pitting corrosion occurred in the uncoated substrates than the carbon-coated substrates after the corrosion test. A statistical machine learning tool; python on Jupyter notebook was used for predictive modelling. The Mean square error (MSE) for the training and testing set is between 0.0009 and 0.0007 respectively, and it produced a training accuracy and testing accuracy of 85% and above for the different bipolar plate materials.