**6. Conclusions**

In this study a new approach for boosting the power of gas turbine power plants by cooling the intake air is analyzed by the energy and exergy methods. The gas turbine inlet temperature is reduced by mixing chilled air from a Brayton refrigeration cycle and the main intake air stream. The air intake temperature depends on two parameters, the cold air stream temperature from the reverse Brayton cycle and the ambient hot humid air conditions. The energy analysis of the coupled Brayton-reverse Brayton cycles showed that the intake air temperature could be reduced to the ISO standard (15oC) and the gas turbine performance can be improved. This study demonstrated the usefulness of employing exergy analysis and the performance improvement was expressed in terms of generic dimensionless terms, *exergetic power gain ratio* (*PGRex*) and *exergetic thermal efficiency change* (*TECex*) factor.

The performance improvement of a GT irreversible cycle of 10 pressure ratio operating in hot weather of 45oC and 43.4% relative humidity was investigated for extraction pressures from 2 to 9 bars and cold to hot air mass rate ratio from 0.1 to 0.5. The results showed that the combustion chamber and the cooling heat exchanger are the main contributors to the exergy destruction terms; the combustion chamber irreversibility was the highest and presented 62 to 85% of the total irreversibility. The heat exchanger comes next with nearly 5 % to 46% of the combustion chamber. The irreversibility of mixing chamber was found to be small compared to other components and can be safely ignored. On basis of the energy analysis the GT power can be boosted up by 19.58 % of the site power, while the exergy analysis limits this value to only 14.66% due to exergy destruction in the components of the plant. The irreversibility can be reduced by optimal design of the combustion chamber, the heat exchanger and selecting optimum operational parameters of the coupled power and refrigeration units.
