The exhaust gases of gas turbine power plant carry a significant amount of thermal energy that is usually expelled to the atmosphere; this causes a reduction in net work and efficiency of gas turbine. On the other hand, the generated power and efficiency of gas turbine plants depend largely on the temperature of the inlet air, So that they both increase as the inlet air temperature decreases. The mentioned two problems can be solved by installing an absorption refrigeration cycle (ARC) at gas turbine inlet, working with thermal energy of exhaust gases. In this research, effect of inlet air cooling on gas turbine performance is studied. The work shows that, the net work and the efficiency will increase by 6-10% and 1-5% respectively for every 10°C decrease of inlet temperature. Since, coefficient of performance (COP) of ARC is low, with high pressure ratios in simple gas turbine (SGT) and with low pressure ratios in regenerative gas turbine (RGT), thermal energy of exhaust gases can not supply all the needed thermal energy for refrigeration cycle. The results show that, when an ejector is included in refrigeration cycle, the need for external energy source required for refrigeration cycle is reduced.

A general mathematical model is developed to specify the performance of an irreversible gas turbine Brayton cycle incorporating two-stage compressor, two-stage gas turbine, intercooler, reheater, and regenerator with irreversibilities due to finite heat transfer rates and pressure drops. Ranges of operating parameters resulting in optimum performance (i.e., hI³38³hII³60%, ECOP³1.65, xloss£0.150 MJ/kg, BWR£0.525, wnet³0.300 MJ/kg, and qadd£0.470 MJ/kg) are determined and discussed using the Monte Carlo method. These operating ranges are minimum cycle temperature ranges between 302 and 315 K, maximum cycle temperature ranges between 1,320 and 1,360 K, maximum cycle pressure ranges between 1.449 and 2.830 MPa, and conductance of the heat exchanger ranges between 20.7 and 29.6 kW/K. Exclusive effect of each of the operating parameters on each of the performance parameters is mathematically given in a general formulation that is applicable regardless of the values of the rest of the operating parameters and under any condition of operation of the cycle.

It has been demonstrated that thermal efficiency can be improved and Nox emission can be reduced in gas turbine cycles by inlet air evaporative cooling. For this method, few studies have been performed using numerical simulations due to the complexity of the combustion and evaporation process. This study numerically and thermodynamically investigated the effect of inlet evaporative cooling on the thermal efficiency and NOx emission of a V94.2 gas turbine. The compressor and turbine are simulated using thermodynamic modeling. However, thermodynamic modeling could be able to calculate the temperature only at the inlet and outlet of devices. Analysis of evaporating cooling effect on combustion chamber temperature distributions and species distribution could be achieved by numerical method. Therefore, the combustion chamber was simulated by numerical modeling using Ansys Fluent 16. The process was simulated at four humidity ratios, including, 0, 25%, 50%, and 75%. Combustion was assumed to occur in a diffusion-type flame. The mass flow rate of fuel and air was 3.64 kg/s and 214.2 kg/s, respectively. Results show that Numerical and thermodynamic solutions have a good agreement with the empirical result. Also, it is observed that the accuracy of the numerical solution is better than the thermodynamic solution. Results indicated a 0.44% improvement in thermal efficiency and a considerable 33.5% reduction of NOx emission at the highest humidity ratio.

An evaluation was conducted to assess the effectiveness of a proposed integrated cycle designed to recover waste heat from a gas turbine for the production of power, hot water, freshwater, and hydrogen. The system comprises a gas turbine, a steam Rankine cycle, an organic Rankine cycle, a PEM electrolyzer, a reverse osmosis (RO) unit, and a domestic water heater (DWH), working together to deliver the primary outputs of power, hydrogen, hot water, and freshwater.  A comprehensive thermodynamic simulation was performed using EES software, accompanied by a parametric analysis to evaluate the cycle's performance under varying input parameters. The results revealed that the system achieves energy and exergy efficiencies of 24.92% and 15.01%, respectively. Furthermore, the combined power output from the system's three turbines and two thermoelectric generators (TEGs) totals 320,412.8 kW. Moreover, the system produces 0.556 kg/s of hydrogen and 18.31 kg/s of freshwater. An exergy loss analysis identified the gas turbine and the steam Rankine cycle as the components with the highest exergy destruction rates. It was observed that increasing the evaporator temperature of the steam Rankine cycle enhances power output from TEG 2 and freshwater production, while simultaneously reducing power output from TEG 1 and lowering the total exergy destruction cost. Furthermore, raising the figure of merit of the TEG improves the system's energy and exergy efficiencies, boosts power generation from the TEG, and enhances freshwater production rates. Finally, it was demonstrated that improving the efficiency of the electrolyzer significantly increases the hydrogen output of the system.