A Comprehensive Thermodynamic Performance Analysis of Gas Turbine Combined Cycles With Rotating Detonation Combustion

Abstract The paper describes a comprehensive thermodynamic analysis of the gas turbine combined cycle (CC) equipped with Rotating Detonation Combustion (RDC). RDC combustors can potentially improve the efficiency of current gas turbines (GTs) through pressure rise in combustion and have recently acquired significant interest due to their continuous detonation and spatiotemporally steadier and more uniform outflow compared to other pressure gain combustion (PGC) approaches. However, the complex detonation combustion dynamics in RDC present challenges in its reduced order modelling. The present work investigates the potential of an RDC to improve the efficiency and power output of CCs for land-based power generation. RDC is represented by a steady-state zero-dimensional model augmented GT cycle with RDC combustor is simulated with realistic component efficiencies, secondary air compressor and blade cooling at pressure ratios from 10–40 at TIT of 1300°C and 1700°C. Simulations are performed in the WTEMP (Web-based Thermo-Economic Modular Program) software, a modular cycle analysis tool developed at the University of Genova. RDC-GT combined cycle is studied with hydrogen as the fuel using a steam bottoming cycle connected through a three-pressure-level reheat heat recovery steam generator (HRSG). Results showed that RDC can improve the cycle efficiency of open cycle GT by 3.2 p.p. and specific work output by 67 kJ/kgair. Similarly, it can increase combined cycle efficiency by up to 1.8 p.p. and specific work by 30 kJ/kgair. It was also found that unlike PGC cycles based on deflagrative constant volume combustion, the RDC cycle shows the maximum efficiency and specific work at a similar pressure ratio as conventional gas turbines. Further, a sensitivity analysis showed higher sensitivity of cycle performance with injection pressure loss in RDC, as compared to that in CVC. Also, with increasing compressor pressure ratio, the benefit over the Joule cycle reduced at a lower rate in RDC, with respect to CVC. Finally, the potential benefits of RDC efficiency and power output were quantified in a validated H-class practical combined cycle at different values of pressure gain. The study conducted is vital in providing further motivation towards realizing practical RDC combustors for more efficient combined cycle powerplants.