Cycle Potential and Aerothermal Impact of SOFC Integration into the Gas Turbine Cycle

Hydrogen GT-SOFC cycles for aviation can offer a step change in efficiency and NOx. The SOFC contributes electrical power, but is also integrated within the GT cycle to receive air and return hot gases. This paper introduces normalised coupling parameters and integration constraints to perform a systematic thermodynamic exploration of GT-SOFC cycles with three main outcomes: a) impacts of SOFC integration on the GT cycle gas composition and thermodynamics, b) the potential of different cycles from SOFC integration, c) universal coupling maps for the cycle potential. The overall efficiency change was found a nearly unique function of the electrical degree of hybridisation (DoHel) due to the high electrothermal potential of the SOFC, while the main enabler of high DoHel - high efficiency is combining low GT specific power with high SOFC specific power. Within the investigated range of air utilisation and cell voltage, low specific power cycles can have Specific Fuel Consumption (SFC) reduction up to -55.7% with optimised Overall Pressure Ratio (OPR) and up to -53% with constrained OPR=10 due to SOFC technology. High specific power cycles can have SFC reduction up to -30% with optimised OPR and up to -14.1% with constrained OPR, when comparing against H2GT cycles with same TET and optimised OPR. With constrained OPR, low specific cycles reach higher efficiencies than high specific power cycles. When AU=0.1, OPR-constrained high specific power cycles perform worse than the H2GT cycle with optimised OPR, and increasing AU should be a priority.