Performance of a gas turbine is mainly depends on the inlet air temperature. The power output of a
gas turbine depends on the flow of mass through it. Inlet air cooling increases the power output by
taking advantage of the gas turbine’s feature of higher mass flow rate when the compressor inlet
temperature decreases. This is precisely the reason why on hot days, when air is less dense, power
output falls off. A rise of 1°C temperature of inlet air decreases the power output by 1%. In this paper
the performance enhancement of gas turbine power plants by cooling the compressor intake air with
an evaporative cooler is studied. This study investigated the effect of inlet air cooling system on the
performance of an existing gas turbine power plant in Nigeria. The results show that for each 5oC
decrease of inlet air temperature, net output power increases around 5-10% and the first and second
law efficiencies increase around 2-5%. It is shown that the amount of this increase is higher when the
pressure ratio is high and turbine inlet temperature is low. The results of this study shows that
retrofitting of the existing gas turbine plant with inlet air cooling system gives a better system
performance and may prove to be an attractive investment opportunity to the Nigeria government and
stakeholders of the plant
