Thermodynamic analyses of a standalone diesel-fueled distributed power generation system based on solid oxide fuel cells

Solid oxide fuel cell (SOFC) recently emerges as a promising technology for distributed power generation with high energy efficiency. While H-2 production and delivery are still the hurdles, diesel can be accessed easily. Thus, it would be of great advantage to generate electricity through an SOFC-based power generation system fueled with diesel. In this work, a standalone diesel-fueled SOFC distributed power generation system combining a steam reformer, a water condenser, a desulfurizer, an SOFC, and a burner is proposed and analyzed thermodynamically. C16H34 is used as a diesel surrogate fuel in the analysis. To realize independent operation of the system, all the heat required by the reformer is supplied by the combustion of the unreacted flue gas from SOFC. With a steam to carbon ratio of 3.5, a reformer temperature of 800 degrees C, and an SOFC temperature of 800 degrees C, the fuel utilization is determined to be 0.72, and the system presents an energy efficiency of 52.4%. The water condenser is of great importance to improve the system efficiency by eliminating fuel-dilution effect attributing to the existence of H2O, without which the energy efficiency decreases to 50.6%. Further, to add a desulfurization unit or to use pre-desulfurized fuel is of great importance as the existence of H2S will cause an immediate drop of the system efficiency of similar to 5% and may lead to irreversible damage. A parametric study is performed and presented and the implications for future research focus are discussed.