Achieving Improved Cycle Efficiency via Pressure Gain Combustors

Abstract

As part of the Department of Energy’s Advanced Gas Turbine Systems Program, an investigation is being performed to evaluate “pressure gain” combustion systems for gas turbine applications. This paper presents experimental pressure gain and pollutant emission data from such combustion systems. Numerical predictions for certain combustor geometries are also presented. We report that for suitable aerovalved pulse combustor geometries studied experimentally, an overall combustor pressure gain of nearly 1 percent can be achieved. We also show that for one combustion system operating under typical gas turbine conditions, NOx and CO emissions, are about 30 ppmv and 8 ppmv, respectively.

The Rayleigh Efficiency of Pressure Gain Combustors

“…Five measurements of pressure gain have been reported in the literature [8,[11][12][13][14]. For all five of these cases the combustor inlet and exit flows are steady, and the combustor temperature ratios are quoted.…”

“…Fig. 10 Estimated Rayleigh efficiencies achieved by other researchers [8,[11][12][13][14] and the Rayleigh efficiency predicted in this work. Equation (21) shows that the effect on its thermal efficiency of introducing a pressure gain combustor into a gas turbine cycle can simply be determined by scaling the combustor's Rayleigh efficiency by a reheat factor, based on the two dead-state pressures, and adding it to the thermal efficiency of the baseline gas turbine.…”

“…The results of the simulation are then used to calculate the terms in Eq. (12). The analysis of this section is used to answer the questions stated in the final paragraph of the introduction.…”

“…(12)] can be used to relate the Rayleigh efficiency of the pulse combustor to production and destruction source terms within the pulse combustor. The values of the production and destruction terms have been calculated from the results of the simulation.…”

The Rayleigh Efficiency of Pressure Gain Combustors

“…The combustor's peak Rayleigh efficiency of 3.8% can be compared with the Rayleigh efficiencies of other published pulse combustors. Five measurements of pressure gain have been reported in the literature [8,[11][12][13][14]. For all five of these cases the combustor inlet and exit flows are steady, and the combustor temperature ratios are quoted.…”