4E analyses of an intercooled-recuperative gas turbine-based CCHP system: Parametric analysis and tri-objective optimization

Abstract

In this paper, a combined cooling heating and power system is proposed for the trigeneration of chilled water, process heat, and electricity. It comprises an intercooled-recuperative gas turbine cycle, an absorption cooling system and a heat recovery steam generator. The absorption cooling system is driven by utilizing the low-grade heat rejected during the intercooling of compressed air and the heat recovery steam generator is operated by recapturing the same from the flue gas. The proposed system is modelled based on energy, exergy, exergoeconomic and environmental analyses. The simulation showed that the system provides a net power of 30 MW, process heat of 29.92 MW, and cooling of 4.72 MW at the base case operating state, with an energy and exergy efficiencies of 83.79 % and 50.60 %, respectively. The optimal case for a proposed system is then determined, with exergy efficiency, system cost, and environmental cost acting as the objective functions to maximise the first and minimise the other two. A parametric analysis is used to find the ideal values of the operating conditions that do not offer a trade-off solution. A tri-objective optimization using the Pareto envelope-based selection algorithm-II is applied to determine the ideal values of the reaming operational conditions that provide trade-off solutions. The technique for order preference by similarity to the ideal solution is also used to select the best optimal solutions from the Pareto front. It is found that the exergy efficiency increased by 2.53 %, and system and environmental costs were reduced by 13.62 % and 18.67 %, respectively.