The main purpose of the present work is to improve the principal characteristics of gas turbine cycle used under hard condition of ambient temperature. That does allow controlling its functioning and recommending a reliable solution remedying at its drop in net power output. A thermodynamic model of gas turbine cycle was established on the basis of energy balance equations utilizing Matlab software. The effects of varying the operating conditions (ambient temperature, compression ratio, turbine inlet temperature, and air to fuel ratio) were investigated. The modeling results show that for each 5°C decrease of ambient air temperature, the net power output and the thermal efficiency of the gas turbine increase respectively around 3% and 1.5%. Also, the turbine net power output increases when the ambient temperature and the air to fuel ratio decrease. The value of gas turbine thermal efficiency is greatly improved when air to fuel ratio is at its minimum value. The maximum thermal efficiency occurs at the highest compression ratio with the lowest ambient temperature and the highest turbine inlet temperature. Furthermore, the addition of a component to the gas turbine cycle, injecting steam upstream of the combustion chamber, effectively improves its power output and thermal efficiency. So, the same net power output of 49.61 MW is obtained at 320 K as that of the cycle without injection at ISO temperature 288 K. The thermal efficiency is stabilized at 39.40% in the same temperature range 288-320 K. The modeling results obtained with the proposed model are in very close agreement with data published in the literature.

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