Experimental investigation of bio-inspired flow field designs for direct methanol fuel cell

Direct Methanol Fuel Cell (DMFC) performance is directly related to the design of the flow fields. Because these areas provide a maximum working performance by the distribution of the reactants to the active sites, the proportional contact of the reactions on the entire surface and the efficient transport of their products. This performance can be increased by changing the type, size or layout of the channels. In this study, leaves of Mulberry (Morus), Fig (Ficus garica) and Loquat (Eriobotrya japonica) trees with 20 cm² active area were tested as flow area for DMFC. For this study, flow field designs were fabricated using metal copper plates. Single cell structures were tested and performance results were compared. In experimental parameters, different Methanol + Water (fuel) concentrations (0.5, 1, 2, 3 and 4 Molar), different fuel temperatures (30, 40, 50, 60 and 70 °C), different air flow rates (0.5, 1, 2, 3 L min⁻¹) and their performances at different fuel flow rates (20, 40 and 60 mL min⁻¹) were tested and compared with the serpentine flow design. When the performance parameters were examined, the best results were obtained at 60 °C, fuel temperature, 1 Molarity, 20 mL min⁻¹ speed fuel and 1 L min⁻¹ air values. The pressure drop in bio-inspired flow areas was reduced and the maximum output power of the new designs was increased. The fig tree leaf provided the highest performance and increased performance by 29 % over serpentine flow.Additionally, of all the flow field designs tested, the serpentine type flow field provided the lowest performance in all tests.