Thermo-economic analysis of a combined cooling, heating and power system based on carbon dioxide power cycle and absorption chiller for waste heat recovery of gas turbine

Abstract

A novel combined cooling, heating and power system which consists of carbon dioxide power cycle, absorption chiller and heaters is proposed in this paper for waste heat recovery of gas turbine. In the proposed cogeneration system, the absorption chiller and heaters are driven by the residual energy of carbon dioxide power cycle and flue gas simultaneously. Detailed mathematic models are established to simulate and evaluate the system from the perspective of thermodynamics and economics. The results of parametric analysis indicate that there is an optimal value for the turbine inlet temperature, at which the exergy efficiency is maximized and the levelized cost of exergy is minimized. As the split ratio increases, the exergy efficiency and levelized cost of exergy of the proposed system first increase then decrease simultaneously. Single-objective optimization is carried out to maximize the exergy efficiency of the proposed system. The optimal results show that the exergy efficiency and levelized cost of exergy of the cogeneration system are 4.62% higher and 0.90 cent lower than that of standalone power cycle, respectively. Compared with the alternative cogeneration system in which only low-temperature flue gas or the waste heat of power cycle is used to drive the refrigeration subsystem and heating subsystem, the exergy efficiency of proposed system is enhanced by 2.89% and 1.3%, respectively. Finally, multi-objective optimization is carried out with exergy efficiency and levelized cost of exergy as objective functions. Pareto frontier is calculated and recommended point is given for the engineering practice.