Performance optimization for an open-cycle gas turbine power plant with a refrigeration cycle for compressor inlet air cooling. Part 1: thermodynamic modelling

A thermodynamic model of an open cycle gas turbine power plant with a refrigeration cycle for compressor inlet air cooling with pressure drop irreversibilities is established using finite-time thermodynamics in Part I of this article. The flow processes of the working fluid with the pressure drops of the working fluid and the size constraints of the real power plant are modelled. There are 12 flow resistances encountered by the working fluid stream for the cycle model. Three of these, the friction through the blades, vanes of the compressor, and the turbines, are related to the isentropic efficiencies. The remaining flow resistances are always present because of the changes in the flow cross-section at the mixing chamber inlet and outlet, the compressor inlet and outlet, the combustion chamber inlet and outlet, the heat exchanger inlet and outlet, and the turbine inlet and outlet. These resistances associated with the flow through various cross-sectional areas are derived as functions of the mixing chamber inlet relative pressure drop, and they control the air flowrate and the net power output. The analytical formulae about the power output, efficiency, and other coefficients are derived with the 12 pressure drop losses. The numerical examples show that the dimensionless power output reaches its maximum at the optimal value and that the dimensionless power output and the thermal efficiency reach their maximum values at the optimal values of the compressor fore-stages pressure ratio of the inverse Brayton cycle.