Document Type : Research Paper

Authors

1 Department of Mechanical Engineering, the University of Guilan, Rasht, Iran

2 Department of Mechanical Engineering, Lahijan Branch, Islamic Azad University, Lahijan, Iran

Abstract

Carbon deposition has a serious effect on failure mechanism of solid oxide fuel cells. A comprehensive investigation based on a two-dimensional model of solid oxide fuel cell with detailed electrochemical model is presented to study the mechanism and the effects of carbon deposition and unsteady state porosity variation. The studies of this kind can be an aid to identify the SOFC optimal working conditions and providing an approximate fuel cell life time. It has been revealed that, due to carbon deposition, the porosity coefficient of the fuel cell decreases. Consequently, a reduction in the amount of fuel consumption along the fuel cell and the chemical and electrochemical reaction rates are resulted which can be clearly seen in the off-gases molar ratio. The percentage of output fuel changes in the timeframe is a useful information for optimizing CHP systems including fuel cells. The percentage of output water vapor, which usually increases compared to the input, decreases by 17% at the end of the working period. Also, unreacted methane in the output of the fuel cell increased by 12%, in other words, it is wasted. The other consequence of carbon deposition, reduced electrochemical and chemical reaction rates and the reduction of temperature difference along the cell. The study shows that after 145 working days, the temperature difference along the cell varies from 117 C for the starting time to 7 C. Also, by reducing current density, the cell output power density decreases by 72% after 145 working days.

Graphical Abstract

Unsteady state numerical study of carbon deposition on the performance of solid oxide fuel cell and variation of porosity

Keywords

Main Subjects

CAPTCHA Image