Investigation of flame-assisted fuel cells integrated with an auxiliary power unit gas turbine

Owing to several unsuccessful attempts of integrating dual chambered solid oxide fuel cell stack with the auxiliary power unit (APU) gas turbine, a novel concept for integration of flame-assisted fuel cells (FFC) with the gas turbine of an APU is presented in this paper. A complete analytical model of the FFC integrated hybrid system is presented. The FFC gas turbine hybrid system is predicted to be up to 30% more efficient at sea level and 16% more efficient at cruising altitudes compared to standard gas turbine cycle. A FFC is characterized experimentally with model combustion exhaust for fuel-rich combustion of JP-5. The fuel cell displayed 75% fuel utilization at the operating voltage of 0.5 V, which is higher than previous studies in this field. The analytically predicted reversible voltage shows good agreement with the open circuit voltage of the FFC experimental results. Analysis of temperature entropy and pressure volume diagrams of the proposed system shows that as the equivalence ratio increases the portion of the total FFC gas turbine hybrid power generated by gas turbine decreases. The breakeven distance and the complexity of the proposed FFC gas turbine hybrid is significantly lower than previous studies.