Part B of this paper focuses on intercooled recuperated cycles where water is injected to improve both efficiency and power output. This concept is investigated for two basic cycle configurations: a Recuperated Water Injected (RWI) cycle, where water is simply injected downstream of the HP compressor, and a Humid Air Turbine (HAT) cycle, where air/water mixing is accomplished in a countercurrent heat/mass transfer column called “saturator,” For both configurations we discuss the selection and the optimization of the main cycle parameters, and track the variations of efficiency and specific work with overall gas turbine pressure ratio and turbine inlet temperature (TIT). TIT can vary to take advantage of lower gas turbine coolant temperatures, but only within the capabilities of current technology. For HAT cycles we also address the modelization of the saturator and the sensitivity to the most crucial characteristics of novel components (temperature differences and pressure drops in heat/mass transfer equipment). The efficiency penalties associated with each process are evaluated by a second-law analysis, which also includes the cycles considered in Part A. For any given TIT in the range considered (1250 to 1500°C), the more reversible air/water mixing mechanism realized in the saturator allows HAT cycles to achieve efficiencies about 2 percentage points higher than those of RWI cycles: At the TIT of 1500°C made possible by intercooling, state-of-the-art aero-engines embodying the above-mentioned cycle modifications can reach net electrical efficiencies of about 57 and 55 percent, respectively. This compares to efficiencies slightly below 56 percent achievable by combined cycles based upon large-scale heavy-duty machines with TIT = 1280°C.

Chiesa, P., 1993, “Thermodynamic Analysis of Humid Air Gas Turbine Cycles (HAT),” Proc. of VII Italian National Congress on Combined Cycles, Milan, Italy, Oct. [in Italian], pp. 169–188.
Crisalli, A. J., and Parker, M. L., 1993, “Overview of the WR-21 Intercooled Recuperated Gas Turbine Engine System—A Modern Engine for a Modern Fleet,” ASME Paper No. 93–GT–231.
Day, W. H., and Rao, A. D., 1992, “FT4000 HAT With Natural Gas Fuel,” Proc. of ASME Cogen-Turbo Congress, Houston, TX, pp. 239–245.
M. A.
, “
A Modified, High-Efficiency, Recuperated Gas Turbine Cycle
, Vol.
, pp.
Horner, M., 1989, “LM8000 ISTIG Power Plant,” presentation given by the GE Marine and Industrial Engine Division, Cincinnati, OH.
Lindgren, G., et al., 1992, “The HAT Cycle, a Possible Future for Power and Cogeneration,” Proc. of the 1992 FLOWERS Congress, Florence, Italy, pp. 125–141.
Macchi, E., Bombarda, P., Chiesa, P., Consonni, S., and Lozza, G., 1991, “Gas-Turbine-Based Advanced Cycles for Power Generation. Part B: Performance Analysis of Selected Configurations,” Proc. of the 1991 Yokohama International Gas Turbine Congress, Yokohama, Japan, Paper 72, Vol. III, pp. 211–219.
Macchi, E., and Poggio, A., 1994, “A Cogeneration Plant Based on a Steam-Injected Gas Turbine With Recovery of the Water Injected—Design Criteria and Initial Operating Experience,” ASME Paper No. 94-GT-XXX.
Rao, A. D., 1989, “Process for Producing Power,” US Patent No. 4,829,763, May.
Rao, A. D., et al., 1991, “A Comparison of Humid Air Turbine (HAT) and Combined-Cycle Power Plants,” EPRI Report IE-7300, Project 2999-7, Final Report.
Roberts, J. A., 1993, “Current and Potential Development in the Use of Aero Derivative Gas Turbines for Power Generations Duties,” CCGT-3 Seminar on Combined Cycle Gas Turbines, held at the Inst, of Mech. Eng., London, Oct.
Stecco, S. S., Desideri, U., and Bettagli, N., 1993, “The Humid Air Cycle: Some Thermodynamic Considerations; Humid Air Gas Turbine Cycle: A Possible Optimization,” ASME Papers No. 93-GT-77 and 93-GT-178.
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