Restrictions of modelling process in gas-steam combined cycle

This paper shows problems of thermal cycles' modelling focused on thermodynamics restrictions of modelling process. These restrictions do not only limit optimum work parameters of combined cycle but they also draw area of exploitation safety of cycle. Shown results were made for two-pressure gas-steam combined cycle with additional gas combustion and with and without steam superheating. In particular rescanning income grade of outlet steam dryness from turbine and income temperatures outlet flue gas from waste-heat boiler on fields correct solutions. This is income for selection optimal solution in respect of efficiency.