Electrochemical and thermodynamic modeling of a CHP system using tubular solid oxide fuel cell (SOFC-CHP)

In this article, first, a CHP system using a solid oxide fuel cell (SOFC) is introduced. The influence of several effective parameters (such as cell temperature, pressure, fuel utilization coefficient, and system air-to-fuel ratio) on SOFC-CHP performance is investigated. In order to obtain an exact solution, the reforming, electrochemical and thermal models are introduced and solved simultaneously. In addition, the power and heat generation diagrams as well as the cell voltage loss under different working conditions are obtained. The results show that as temperature and pressure increase, the cell power increases; however, the temperature is more effective. Also, the results indicate an overall SOFC-CHP system efficiency of about 73%. Finally, the optimum air-to-fuel ratio and fuel utilization coefficient are determined as 9.4 and 0.85, respectively. As a final conclusion, the selection of system operating conditions must be made on the basis of the thermal and electrical needs of the specific building.