A novel two-phase model for predicting the bubble formation and performance in microfluidic fuel cells

The presence of gas affects the performance of liquid-fed micmfluidic fuel cells. It is, therefore, necessary to analyse the influence of gas/liquid flow on cell characteristics. A two-phase computational model, which couples hydrodynamics, mass transport, electrochemical reaction kinetics, and phase field theory based on bubble dynamics theory, is developed for air-breathing micmfluidic fuel cells with a flow-over anode. The model is used in this study to investigate the effect of two-phase flow on cell performance. Results suggest that bubbles which attach to the anode wall may degenerate cell performance. Moreover, an increased carrier liquid flow rate and contact angle plays a positive role with regard to removing bubbles in the channel. A decrease in surface tension also substantially contributes to bubble separation from the anode interface. In addition, an increased fuel flow rate and fuel concentration enhance the current and power densities within limits, but fuel utilisation and exergy efficiency are considerably sacrificed. Furthermore, an increasing contact angle and reduced surface tension can be beneficial to cell performance. The present work lays the foundation for further optimisation of cell performance via micmfluidic fuel cells two-phase analysis.