Modeling and multi-objective optimization of a combined cooling, fresh water and power system for gas turbine waste heat recovery

Abstract

Abstract Increasing the efficiency of gas turbine cycle (GTC)-based energy systems and reducing the irreversibility of its processes is one of the challenges that researchers are considering today. The use of waste energy of GTC and inlet air cooling to it are two techniques that help to increase the efficiency of energy production of these systems while the simultaneous it use has been less considered in multiple-generation systems. In this study, a new GTC-based tri-generation system consisting of organic rankine cycle (ORC), thermoelectric generator (TEG), reverse osmosis (RO), and absorption refrigeration cycle (ARC) subsystems is presented. This system simultaneously generates electricity, freshwater, and cooling. The total cooling capacity is used in two parts: user demand and inlet air cooling to the GTC compressor. Tri-generation system was examined from three views energy, exergy and exergoeconomic. The results of the thermodynamic analysis showed that the simultaneous use of two waste heat recovery and inlet air cooling of GTC techniques in the tri-generation system reduces the exergy destruction cost rate of the system while increasing the total energy and exergy efficiencies. To improve system performance after a parametric study, a three-objective optimization was performed using the TOPSIS method. The comparison of the results of optimal and design conditions showed that the exergy destruction rate of the system has decreased in optimal conditions and the highest rate of exergy destruction, which is related to the GTC combustion chamber component, has decreased by 66.8 kW. In addition, the total capital cost rate of the system in optimal conditions was reduced by 0.33 kW compared to the design conditions. According to the optimal results, the best performance of the system is in the conditions of the compressor pressure ratio of GTC 8.795 and the turbine inlet temperature of GTC 1505 K that the system has COP 0.74, total exergy efficiency 55.51%, and total product cost rate 32.28 $/h.