Investigation of hydrodynamic characteristics and developmental mechanisms of gas-liquid two-phase flow in microfluidic microbial fuel cells

Microfluidic microbial fuel cells (MMFCs) as a cutting-edge technology have shown great potential in distributed energy recovery and environmental pollution control. Existing research mostly focuses on liquid-phase transport, but the gas affects the internal mass transfer, reaction kinetics, and final output performance of the system remain unclear, and there is a lack of precise mathematical models specifically describing gas-liquid two-phase flow. This study is the first to establish a two-dimensional two-phase flow numerical model that couples biological electrochemical reactions and interfacial transport among multiple physical fields. The core innovation of this model lies in introducing the concept of gas volume fraction, which quantitatively describes the generation, distribution, and migration behavior of carbon dioxide bubbles in porous electrodes and microchannels, thus breaking through the overly idealized predictions of traditional single-phase models for system performance. Based on this model verification, the coupling influence mechanism of key parameters on the output performance of MMFCs and the spatiotemporal distribution of electroactive biofilms are systematically explored. The research results show that the maximum gas removal rate reaches 73.18%, and the optimal power density is 1274.94 W/m3.