Research on thermodynamic performance of a gas-steam combined cycle with rotating detonation combustion

Conventional gas-steam combined cycles are constrained by the substantial irreversibility of constant-pressure combustion, whereas integrating a rotating detonation combustor (RDC) may lower the turbine exhaust temperature and thereby impair the steam bottoming cycle. In this study, a thermodynamic model of a methane-fueled RDC-based gas-steam combined cycle is developed and compared with a conventional constant-pressure-combustion combined cycle. The effects of compressor pressure ratio and ambient temperature on cycle performance are investigated, together with an exergy analysis. The results show that intrinsic pressure gain of RDC markedly increases power output of gas-turbine topping cycle and offsets the reduction in steam-cycle power. Under the design condition, the relative efficiency improvement of the proposed combined cycle exceeds 3.6%, and the relative improvement reaches 7.255% at compressor pressure ratio of 6. The RDC reduces combustion exergy destruction by 4.16%-4.89%, with greater benefits at lower pressure ratios and lower ambient temperatures. These findings provide a thermodynamic basis for the design and optimization of RDC-based combined-cycle power systems.