Date of Award
Master of Science
Solid Oxide Fuel Cells (SOFC) as the heat source for a heat engine power cycle can greatly increase the overall efficiency. The maximum efficiency is limited in at least the following ways. All thermal heat engine power cycles are limited by the Carnot efficiency which is a function of the hot and cold reservoirs the cycle operates between. Another irreversibility that limits the maximum efficiency of a fossil fuel cycle is the combustion reaction. In a boiler or combustion chamber, the chemical reaction of combustion happens spontaneously, meaning that the reaction happens without being used to generate power. A fuel cell decreases this irreversibility because it generates work as the combustion reaction happens. A SOFC can do this without an expensive catalyst due to the higher operating temperature. The power generated by the fuel cell can be added to the power generated by the thermal power cycle operating from the exhaust of the SOFC. The total work generated would be more than the system would have generated from just the heat engine resulting in a higher overall efficiency for the cycle. A SOFC and a recovery power cycle was simulated in Engineering Equation Solver (EES) to solve for ideal operating conditions. The fuel cell and gas turbine system had a net power output of 136 MW and had an efficiency of 60.84%, assuming the fuel cell had an 85% fuel utilization.
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