Investigation of corner effect on micro-scale flow of μDMFC

Abstract

The effective removal of carbon dioxide (CO2) in the anode microchannels is of great importance to the performance of a micro direct methanol fuel cell (@mDMFC). The gathered bubbles block part of the methanol mass transfer area from anode flow field to catalyst layer, causing a reverse effect on cell performance. Unlike the flow in the straight channel, the gas emission at the corner is more critical because of the corner effect. The work investigates the two-phase transport between CO2 bubble dynamics and micro-fluid at the corner from a Mesoscopic perspective. A two-dimensional, nine-velocity Lattice-Boltzmann model coupled with surface tension, buoyancy force and the fluid-solid interaction force is adopted in this work to simulate the dynamics of micro flow. Simulation results indicate that the emission speed of CO2 gas patterned with the circular corner is faster than that with orthogonal corner. To verify the simulation results, a visual study of the CO2 bubble behavior in the micro channels of a transparent @mDMFC is conducted, and the cells patterned with different structures are tested. Compared with the cell with orthogonal corner, the cell patterned with circular corner exhibits a substantial increase of 21% in peak power density.