Thermo-Economic Analysis of Gas Turbines Power Plants with Cooled Air Intake

Gas turbine (GT) power plants operating in arid climates suffer from a decrease in power output during the hot summer months. Cooling the intake air enables the operators to mitigate this shortcoming. In this study, an energy analysis of a GT Brayton cycle coupled to a refrigeration cycle shows a promise of increasing the power output with a slight decrease in thermal efficiency. A thermo-economic algorithm is also developed and applied to the Hitachi MS700 GT open cycle plant at the industrial city of Yanbu, the Kingdom of Saudi Arabia (latitude 24°05” N and longitude 38° E). The results show that the power output enhancement depends on the degree of chilling the air intake to the compressor. Moreover, maximum power gain ratio is 15.46% whilst a slight decrease in thermal efficiency is of 12.25% for this case study. The study estimates the cost of the needed air cooling system. The cost function takes into consideration the time-dependent meteorological data, operation characteristics of the GT and air cooler, the operation and maintenance costs, interest rate, and lifetime. The study also evaluates the profit of adding the air cooling system for different electricity tariff.