In this study, a combined cycle consisting of Brayton, Rankine and compression refrigeration cycles is thermodynamically evaluated for power generation and cooling. The combined cycle is simulated in EES software and its thermal efficiency is calculated using the first law of thermodynamics. Using three heat exchangers with a thermal efficiency of 90%, the heat output from the compression refrigeration cycle is used for preheating and the waste heat of the Brayton cycle is used to produce steam in the Rankine cycle. Air, water, and R134a are the working fluids in the Brayton, Rankine, and refrigeration cycles. Mass flow rates of 5, 10 and 20 kg/s are considered for water, R134a refrigerant and air, respectively. The effect of the working fluid rate on the thermal efficiency of the combined cycle is investigated. By energy analysis, the thermal efficiency of the Brayton cycle was 49.29%, the Rankine cycle was 27.68%, the coefficient of performance of the refrigeration cycle was 4.38%, and the thermal efficiency of the combined cycle was 48.84%. The results show that with increasing air flow rate, the thermal efficiency of the combined cycle increases, but with increasing R134a refrigerant flow rate and water vapor, the combined cycle efficiency decreases