Analysis of inlet air cooling via reverse brayton cycle in gas turbines

One of the biggest problems encountered in power generation plants using gas turbines is the decrease in the net power produced from the system due to the increase in ambient air temperature. It is a common practice to cool the inlet air of the gas turbine compressor, especially in systems used in regions with hot climates, to prevent power capacity drop from the system and increase the net power. Fogging, evaporative cooling, vapor compression cooling, and absorption cooling are among the methods used for inlet air cooling in gas turbine systems. In addition to these traditionally used cooling techniques, alternative cooling techniques are also being in research. In this study, thermodynamic analyzes were carried out by integrating the Reverse Brayton cycle, which is used for cabin air-conditioning in aircrafts, into the cycle for cooling the compressor inlet air of the open type gas turbine cycle. The analysis of the Reverse Brayton cycle integrated gas turbine cycle was performed with the aid of the Engineering Equation Solver (EES) code, depending on the compressor inlet air temperature, compressor inlet air relative humidity, and pressure ratio parameters. In addition, the same analyzes were performed for the fogging method to compare the Reverse Brayton cycle with another inlet air cooling method. Parameters used in the study are, ambient relative humidity 10-90%, ambient temperature 10-50°C, gas turbine pressure ratio 2-13, and Reverse Brayton cycle pressure ratio 1.1-1.8. As a result, Reverse Brayton cycle integrated gas turbine cycle for the purpose of the inlet air cooling the gas turbine compressor under conditions where ambient temperature is 45°C, ambient relative humidity is 60%, the gas turbine cycle pressure ratio is 12.2, and the Reverse Brayton cycle pressure ratio is 1.5, it has been shown that it provides a 7.96% power increase and 0.15% decrease in thermal efficiency compared to the gas turbine cycle alone. When cooling with the fogging method under the same conditions, it provides a power increase of 5.52% and thermal efficiency increase of 0.7% compared to the gas turbine cycle alone