Experimental and numerical investigation of bio-inspired flow field design for direct methanol fuel cell

In this thesis, bio-inspired flow channel designs for direct methanol fuel cells (DMFCs) were investigated. The study focused on bio-inspired models of loquat, fig, and mulberry leaves, which were initially determined through numerical simulations and subsequently tested experimentally. Experimental investigations explored parameters such as methanol concentration, fuel temperature, fuel flow rate, and air flow rate, comparing the bio-inspired designs with the commonly used serpentine flow channel. The comparison revealed that the bio-inspired fig leaf design achieved approximately 29% higher peak power density compared to the serpentine design, demonstrating a significant performance enhancement for DMFCs. To ensure the reliability of the experimental results, electrochemical impedance spectroscopy (EIS) measurements were conducted. The best performance parameters were obtained at a fuel temperature of 60 °C, a 1 M methanol-water (MeSu) solution, a fuel flow rate of 20 mL/min, and an air flow rate of 1 L/min. Experimental studies for the new designs were repeated to confirm the performance outcomes for each flow channel. Additionally, the two-phase flow of carbon dioxide (CO2) gas and MeSu liquid in the anode flow field was visualized at different current densities and times using video recordings.