Parametric Analysis of Combined Gas-Steam Cycles

Combined gas-steam cycles have been analyzed from the thermodynamic point of view. Suitable thermodynamics indices—explained in Appendix A—have been utilized. The parameters that most influence efficiency have been singled out and their ranges of variability have been specified. Calculations have been carried out—see Appendix B—taking into account the state of the art for gas turbines and the usual values for the quantities of steam cycles. The results are given. The maximal gas turbine temperature has been varied between 800°C and 1400°C. The gas turbine pressure ratio has been analyzed in the range of 2–24. Afterburning has also been taken into consideration. Maximal efficiency curves and the corresponding specific work curves (referred to the compressed air) related to the parameters of the analysis are given and discussed.