Energy-exergy analysis of gas turbine cycle in a combined cycle power plant

In this study, the performance characteristics of a gas turbine cycle in a combined cycle power plant (CCPP) were examined for a set of design and operational parameters. In this context, the effect of inlet air cooling (IAC), gas turbine inlet temperature (TIT) and steam injection gas turbine (STIG) on gas turbine power, thermal and exergy efficiency were taken into consideration. The analysis was carried using theoretical calculations by taking the experimentally measured data of a GT 13 D2 type gas turbine in operation conditions as a starting point. The results show that cooling the compressor inlet air temperature from 30 degrees C to 0 degrees C leads to 13.6% and 4% increase in power output and thermal efficiency, respectively. The results also indicate that changing the turbine inlet temperature from 990 degrees C to 1750 degrees C leads to an increase in thermal efficiency by 11% and exergy efficiency by 39% as well as an increase in turbine power output, as 130%. STIG method provides almost the same amount of power increase like IAC method and it is seen that the amount of increase in efficiency in this method is in a higher level compared to IAC method. Moreover, the amount of 5% compressor inlet air steam injection to combustion chamber leads to an increase in thermal efficiency by 10.6% and exergy efficiency by 37% and as well as an increase in turbine power output, as 11%.