One-Dimensional Macroscopic Model of Solid Oxide Fuel Cell Anode with Analytical Modeling of H_2/CO Electrochemical Co-oxidation

摘要

A one-dimensional mathematical model is proposed for macroscopic electrochemistry and transport in the anode of solid oxide fuel cells using synthesis or reformed gas as fuel. Define two key variables, hydrogen current fraction and enhancement factor, for H_2 and CO electrochemical co-oxidation, we develop an analytical approximation solution of the decoupled charge/mass transfer. Different from the state-of-the-art studies, this framework allows the effective exchange current density of CO oxidation to be fuel-composition-and-current-density dependent rather than constant, and therefore makes an adaptive extension of the macroscopic electrochemistry from pure H_2 and CO fuel to syngas fuel. By driving the equilibrium movement of water shift gas reaction, the operating current density and fuel compositions have an important role in H_2/CO competition reactions. The model in this article has been validated by experimental polarization curves on a button cell.