Efficiency estimation of solid oxide fuel cell integrated with iso-octane pretreating system

Abstract

The effect of iso-octane pretreatment on the efficiency of solid oxide fuel cell (SOFC) is important for selecting suitable pretreating technology. In this work, oxidation index and equivalent fuel utilization for SOFC with pure iso-octane as fuel and pre-treated iso-octane as fuel are designed in a novel way, and then the stable operating condition and efficiency of SOFC integrated with iso-octane pretreating system are investigated based on the fuel composition and anode gas characteristics. At low temperatures, solid carbon and methane are easy to be formed for iso-octane pretreatment, while H2 and CO are easy to be produced at high temperatures from thermodynamics. Steam reforming of 1 mol of iso-octane can produce 17 mol of H2 and 8 mol of CO, and thus steam reforming of iso-octane has little effect on the efficiency of SOFC. When the O/C ratio is 1.5 and the equivalent fuel utilization is 90%, the electrical efficiency of SOFC is 64.6% for steam reforming of iso-octane if the heat is provided by anode off-gas, which is 10.9% higher than that with the fuel from autothermal reforming of iso-octane and 32.6% higher than that with the fuel from catalytic partial oxidation of iso-octane. Through investigating the effect of iso-octane pretreating technology on the oxidation index of anode gas and real fuel utilizations of SOFC at different equivalent fuel utilizations, the accurate effect of iso-octane pretreatment on the efficiency of SOFC can be calculated and analyzed for iso-octane-fuelled SOFC, which can provide good guidance for the experimental process and practical application of iso-octane-fuelled SOFC.