Modeling of mass transfer in a T-shaped microfluidic fuel cell.

The development of microelectronic devices has increased the need for a power supply with high power density for long-term operation. In this article, microfluidic fuel cells (MFCs) are first introduced, and second, due to the significant effect of mass transfer on their performance, mass transfer in these fuel cells is investigated. MFCs have small dimensions and simple geometry, and formic acid and oxygen dissolved in sulfuric acid are usually used as fuel and oxidizers, respectively. The equations of continuity, momentum, and mass transfer have been solved in three dimensions using Open-Foam open-source software to model the MFC and then validated, with the results available in the references. Fick's equation was used to calculate the rate of diffusion, and the Butler-Volmer equation was used to calculate the rates of electrochemical reactions in catalyst layers. Preliminary results indicated that the performance of this fuel cell is greatly limited by poor fuel utilization, which is consistent with the experimental data. The flow is fully developed in this short distance from the inlet, and in the fully developed area, the ratio Umax/U is equal 2.1. The mixing zone located at the interface of fuel and oxidizer is in the shape of an hourglass in the cross-section, and as the inlet velocity increases, its thickness decreases along the channel. Also, as the flow moves along the channel, the thickness of the layer with a low concentration near the electrodes increases. [ABSTRACT FROM AUTHOR]