Thermodynamics and emission analysis of a modified Brayton cycle subjected to air cooling and evaporative after cooling

Highlights: • Modified cycle performance was assessed theoretically from the energetic aspect. • Validation study was performed based on temperature and emission analysis. • Detailed energy analysis was conducted in terms of 1st and 2nd law efficiencies. • The effect of major parameters on the exergy destroyed of system components. • The theoretical measurement of nitrogen oxides and carbon monoxides were studied. - Abstract: In the current research, a gas turbine fueled by natural gas and integrated with the reversed Brayton cycle for cooling the intake air then evaporation was studied. The performance of the proposed cycle was assessed theoretically from energetic and environmental aspects. To achieve this, first a validation study has been performed based on temperature and emission analysis of a gas turbine model. Second, detailed energy analysis was conducted to identify the causes and locations of thermodynamic imperfection in terms of 1st and 2nd law efficiencies. Third, analytical relations for the theoretical measurement of two key emissions namely; Nitrogen Oxides and Carbon Monoxides were studied and applied. The effects of important influencing parameters such as the ambient temperature, ambient relative humidity, extracted mass rate and equivalence ratio on energy and environmental performance of the cycle was investigated. It was found that the proposed gas turbine cycle can bring down the emission levels to the regulatory standards (less than 35 ppm). It was also able to increase the power output by 31% with a slight drop in its efficiency. Therefore, the results of this research may be used to determine the range of operating parameters at which the gas turbine could be operated which can provide a considerable reduction in the emissions while maintaining a higher performance.