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Abstract
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An efficient solar-geothermal based system is proposed to produce desired cooling, heating, and power. The system consists of the organic Rankine and ejector refrigeration cycles. A booster is also employed to increase the cooling capacity. To better realize the system performance, energy, exergy and thermoeconomic analyses are investigated for three working fluids including R423A, R1234ze and R134yf. Two single-objective function optimization studies are conducted with the fluid that exhibits the lowest exergy destruction rate. In the first one, a thermodynamic objective is optimized, while the second deals with a thermoeconomic function. A third optimization task weights these two objectives simultaneously, approaching a multi-objective study. At the base case conditions, the results showed that the system with R423A working fluid has the lowest total exergy destruction rate equal to 405.3 kW. The outcomes for this working fluid show that the levelized cost of cooling, heating and electricity obtained from multi-objective optimization is less by 91.17% and 73.22% compared to the cases when the cycle is optimized from energy efficiency and cost viewpoints, respectively. Moreover, energy efficiency is 13.53%-points higher than the base case conditions. The energy and exergy efficiencies are determined as 44.02% and 7.389%, respectively, under multi-objective optimal design conditions.
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