Page 135 - Advanced Gas Turbine Cycles

Chapter 6. ‘Wet’ gas turbine plants I07

than the RWI calculations, peaking at even higher pressure ratios (27 at 1250°C, 50 at
15Oo0C).
Macchi et al. did not undertake parametric studies of the CHAT cycle and there appears
to be no comparably thorough examination of this cycle in the literature; but Nakhamkin
describes a prototype plant giving a thermal efficiency of some 55% at a very high pressure
ratio, Le. about 70, compared with the dry CICBTBTX cycle optimum of about 40 shown
in Fig. 6.17.
van Liere’s calculations for the TOPHAT cycle, also shown in Fig. 6.17, show a
remarkably flat variation in efficiency for a wide variation in specific work.

6.7. Conclusions

The main conclusions from the work on water injection describes in this chapter are as
follows:
the well established STIG cycle shows substantial improvement on the dry CBT
cycle, mainly in specific work but also in thermal efficiency;
the simple EGT plant (a ‘wet’ CBTX cycle) cycle gives an increase in the thermal
efficiency; the optimum pressure ratio is still quite low, but a little above that of the
dry CBTX cycle;
the intercooled RWI, HAT, REVAP and TOPHAT cycles give increases of efficiency
and specific work on the dry CICBTX cycle, at the expense of the added complexity,
optimum conditions occumng at higher pressure ratios;
the CHAT cycle, interpreted as an evaporative modification of the ‘ultimate’ dry
CICBTBTX plant, appears to yield high efficiency at an even higher pressure ratio.

References

[I] Frutschi, H.U. and Plancherel, A.A. (1988). Comparison of combined cycles with steam injection and
evaporation cycles, Proc. ASME COGEN-TURBO 11, pp.137- 145.
121 Lloyd, A. (1991). Thermodynamics of chemically recuperated gaq turbines. CEES Report 256, Centre For
Energy and Environmental Studies, University Archives, Department of Rare Books and Special
Collections, Princeton University Library.
131 Fraize, W.E. and Kinney, C. (1979). Effects of steam injection on the performance of gas turbines and
combined cycles, ASME J. Engng Power Gas Turbines 101.217-227.
[4] Hawthorne. W.R. and Davis, G.de V. (1956). Calculating gas turbine performance, Engineering 181,
361 -367.
151 Horlock, J.H. (1998). The evaporative gas turbine, ASME J. Engng Gas Turbines Power 120.336-343.
[61 El-Masri, M.A. (1988). A modified high efficiency recuperated gas turbine cycle, J. Engng Gas Turbines
Power 1 IO, 233-242.
[71 Horlock, J.H. (1998). Heat exchanger performance with water injection (with relevance to evaporative gaq
turbine (EGT) cycles), Energy Conver Mgmt 39(16-18). 1621-1630.
[SI Cem, G. and Arsuffi, G. (1986). Calculation procedures for steam injected gaq turbine cycle with
autonomous distilled water production, ASME Paper 86-GT-297.
[91 Macchi, E., Consonni, S., Lozza, G. and Chiesa. P. (1995). An assessment of the thermodynamic
performance of mixed gas-steam cycles, Parts A and B, ASME J. Engng Gas Turbines Power 117,
489-508.