Lattice Boltzmann Simulations of Bubble Dynamics at the Anode of a µDMFC

This paper presents the bubble transport phenomenon at the anode of a micro direct methanol fuel cell (μDMFC) from a messooscopic viewpoint. Carbon dioxide bubbles generated at the anode may block part of the catalyst/diffusion layer and also the flow channels that cause the μDMFC malfunction. Lattice-Boltzmann methods (LBM) were employed in this paper to simulate the two phase flow in a simplified micro channel which emulates the bubble dynamics in the porous diffusion layer and the flow channel. A two-dimensional, nine velocity model (D2Q9) was established. The surface tension, buoyancy force were treated as source terms in the momentum equation. Bounce back boundary conditions were assumed at the fluid-solid interface in this model. Simulation results and parametric studies showed that the pore size, the stream flow rate and the hydrophilic effect between the fluid and the solid wall play the major roles in the bubble dynamics. Larger pore size, higher methanol stream flow rate and greater hydrophilicity are preferred for bubble removal at the anode diffusion layer and also the flow channels.