Performance Analysis of E-, F- and H-Class Gas Turbines with Pressure-Gain Combustion in Simple- and Combined-Cycle Operation

Efficiency improvements in gas turbines have been realized in recent decades by raisingthe turbine inlet temperature. This work devotes attention to pressure-gain combustion(PGC), which is a technology capable of yielding the same time-averaged combustor outlettemperature as conventional Brayton-Joule cycles but at a higher pressure. Here, PGCis implemented in a thermodynamic cycle wherein the compression system operates ata lower pressure ratio compared to the reference Brayton-Joule cycle. Focusing on E-,F- and H-class gas turbines, representative of three different technologies, the possiblePGC advantages in both simple- and combined-cycle modes are investigated by meansof in-house simulation code. Specifically, this work includes the energy penalty relatedto the PGC system cooling in the cycle analysis. In detail, the effects of different coolantamounts on the PGC system, as well as the lower efficiency at the first expansion stagecompared to conventional gas turbine systems, are analyzed. Among the three classesof gas turbines, E is the one wherein the advantages are more significant, with ultimateefficiency values in simple-cycle mode calculated in the range of 38% to 41%. The higherthe gas turbine technology and power class, the lower the benefit, and current H-classgas turbines already start from a higher efficiency level. Anyway, focusing on the latter,performance improvements for the PGC combined cycle seem to be possible, with efficiencygreater than 65%, exceeding the current state-of-the-art systems.