Evaluation of Gas Turbine Inlet Air Cooling Impact on Power Output in Kwara State

Gas turbine power output is inversely related to ambient air temperature, making inlet air cooling a practically important performance enhancement strategy in tropical countries such as Nigeria. This study evaluates the impact of turbine inlet air cooling on the power output performance of gas turbines at the Egbin Gas Turbine Power Plant expansion unit and an industrial co-generation facility in Kwara State. The research employs an experimental performance measurement methodology, collecting turbine operational data under natural ambient conditions and during periods when inlet air cooling is activated using fogging and inlet evaporative cooler systems. Performance metrics recorded include net power output, heat rate, compressor inlet temperature, compressor pressure ratio, and exhaust gas temperature. Ambient temperature data from the Nigerian Meteorological Agency (NIMET) are correlated with power output records to develop empirical correction curves for Kwara State seasonal temperature patterns. Findings demonstrate that inlet air fogging systems recover between 4 and 7 percent of power output during the hot dry season (November to March) when ambient temperatures regularly exceed 38 degrees Celsius in the North Central zone. The economic value of this recovered power, calculated at the prevailing generator capacity tariff, is shown to justify the capital investment in inlet cooling systems within three years of installation. Recommendations include retrofitting inlet cooling systems on all simple-cycle gas turbines operating in Nigeria's hot climate zones and integration of inlet cooling control into turbine management systems. Keywords: gas turbine, inlet air cooling, power output, Kwara State, turbine performance.