Narrow middle channel design in counter-flow microfluidic fuel cell with flow-through electrodes

Output performance of counter-flow microfluidic fuel cell is hampered by its significant internal ohmic resistance. In this work, narrow middle channel design is introduced to the counter-flow microfluidic fuel cell with flow-through electrodes to ease the internal ohmic resistance issue and realize increased fuel utilization and improved power density simultaneously. Systematically numerical investigations are performed to validate the feasibility and evaluate the prospect of the narrow middle channel design. Meanwhile, in-depth analyses are provided to explore the mechanisms behind the distinctive cell characteristics. Corresponding results demonstrate that the width of the middle channel in the counter-flow microfluidic fuel cell with flow-through electrodes can be safely reduced from the commonly used 1–2 mm–0.3 mm without reactant crossover and obvious increase in the energy consumption for the pumping of the reactant streams. Superiority of the narrow middle channel design is more significant in the high reactant concentration and high flow rate case where an increase of 30.29 % is observed in the peak power density when the middle channel width reduces from 1 mm to 0.3 mm under the reactant concentrations of 4 M and flow rate of 120 μLmin−1.