First law thermodynamic analysis of the recuperated Humphrey cycle for gas turbines with pressure gain combustion

Abstract

The current work is an analysis of the recuperated Humphrey cycle. Three cycle topologies are studied with and without turbine cooling. The study focuses on the interconnection between combustor pressure gain and heat recuperation. It is an attempt to optimize the cycle topology and configuration to achieve the maximum possible cycle efficiency. It is found that the best option to use recuperation in the Humphrey cycle is to operate the combustor at stoichiometric conditions, without preheating the air fed to it. The combustion air comes effectively form a compressor air bleed. The remaining air is further compressed at the combustor outlet pressure and is fed to a plenum between combustor and turbine once it is preheated by the recuperator. This cycle configuration results in the best performance both in terms of efficiency and specific work. Specifically, an efficiency increase between 2 to 5 percentage points is achieved. This work concludes with a feasibility study for shockless explosion combustion (SEC) for the Humphrey cycle configurations and topologies that achieve an efficiency advantage against the Joule cycle. It is found that realistic SEC combustor lengths and efficiency gains can be simultaneously achieved, albeit not at the cycle configurations with the best performance