Abstract
This paper discusses the thermodynamics of power cycles where steam or water are mixed with air to improve the performance of stationary gas turbine cycles. A general computer simulation program is presented; several components (compressor, combustor, turbine, recovery boiler, saturator, recuperator, inter-cooler, after-cooler) are modelled obtaining a transfer function between in-coming and out-coming fluids.
Coupled with this simulation program, an optimisation is carried out using a decomposition strategy based on the second law of thermodynamic and a concept for costing the components of the cycles. A large number of decision variables can by optimised with enhanced convergence to an optimum.
As results, a large number of simulations and optimisations are performed for three different plants (STIG, HAT and a cycle with water injection both in the compressor and in the combustor). A wide number of comparisons shows the difference between the cycles and the power level at which each plant gives the lowest exergoeconomic costs.
