Role of Carbon Dioxide Reforming Reaction Rate of Methane in Solid Oxide Fuel Cell Simulation: Effect of Inlet Fuel Related Parameters

Abstract

ABSTRACT The present study assessed the reaction rate of methane carbon dioxide reforming (MCDR) in solid oxide fuel cells (SOFCs). This reaction rate was compared with the rates of the methane steam reforming (MSR), and the water-gas shift (WGS) reactions to evaluate its importance in simulating a SOFC. In addition, the effect of the system inlet parameters involving the Reynolds number, steam to carbon ratio (S/C), and CO2/CH4 on reaction rate variations was investigated. In this regard, a numerical model having axial symmetry was used to simulate the reaction of MCDR. Based on the results of the present study, the rate of this reaction was significant compared to that of the MSR, and WGS reaction and its ignoring cause inaccuracy in simulation results. According to the parameters investigated in this study, the change in S/C led to a low variation in the MCDR reaction rate. As the S/C increases from 0 to 0.5, the reaction rate increases from 8.9 to 12.5. Further, since the rate of CO2 absorption in the catalyst was very less compared to that of CH4, the effect of the molar ratio of CO2on the reforming reaction rate is much greater than the effect of the molar ratio of CH4. This can decrease the reaction rate of MCDR when the CO2 molar ratio reduces and CH4 molar ratio and the multiplication of the molar ratios of CH4 and CO2 increases. As the Reynolds number increases from 7.5 to 27.5, despite increasing the multiplication of the CH4 and CO2 molar ratios by 86%, this reaction rate decreases by 47% due to the decrease in CO2 molar ratio by 34%. Additionally, the greater impact of CO2 molar ratio led to an increase in the CO2/CH4 molar ratio possessed the greatest effect on the rate of this process. The addition of molar ratio from 0 to 0.5 resulted in increasing the rate of MCDR in the center of SOFC from 8.9 to 21.8 mol/m3/s.