Steam injected Humphrey cycle for gas turbines with pressure gain combustion

Abstract

Gas turbines are a mature technology and any increase in their efficiency comes at high R&D cost. Pressure Gain Combustion (PGC) has emerged as a concept to significantly improve their efficiency. Technically, PGC is realized through detonative combustion or approximations of constant volume combustion. The latter include pulsed resonant combustion and shockless explosion combustion. Detonation combustion is typically realized as pulsed or rotating detonation combustion. Gas turbine processes with PGC are modeled with the Humphrey or the ZND cycle. Most thermodynamic studies focus on the basic gas turbine cycle with PGC. The current work extends this scope by presenting a thermodynamic analysis of the steam injected Humphrey cycle. Steam injected gas turbines have several advantages that complement these of PGC. Steam injection can reduce NOx emissions and can be used in PGC gas turbine cycles to maximize combustor pressure gain. The present work applies 0-D thermodynamic modeling to compare the thermal efficiency of the Humphrey-STIG cycle to that of the Joule-STIG cycle. An optimum method to realize heat recuperation through steam injection in a Humphrey cycle is defined. The work concludes by defining Humphrey-STIG cycle configuration that result in realistic lengths of shockless explosion combustors.