Design and optimization of a novel dual-loop bi-evaporator ejection/compression refrigeration cycle

Abstract

Exploration of the ejector refrigeration cycle (ERC) in the combination with vapor compression refrigeration cycle (VCRC) is highlighted in recent decades. Therefore, in this study a novel dual-loop bi-evaporator ejection-compression refrigeration cycle for freezing and air-conditioning applications is proposed and analyzed based on the energy, exergy, exergoeconomic and sustainability viewpoints. The proposed refrigeration cycle is driven by a low-grade heat source and is constituted of two separate loops and a common condenser between two these loops. A comprehensive parametric study and working fluid screening are carried out, showing that among all screened working fluids, R134a is appropriate one which meets most energy, economic and sustainability criterion. Also, the results of exergy analysis showed that among all components vapor generator accounts for the biggest exergy destruction rate followed by ejector for all selected working fluids. In addition, multi-objective optimization of the proposed cycle is carried out by considering of vapor generator pressure, evaporator (I) temperature, evaporator (II) temperature, and condenser temperature as decision variables, using genetic algorithm (GA). The results of the optimization demonstrated that the optimum cooling capacity, coefficient of performance (COP), exergy efficiency, and cost of cooling (for when R134a is used) can be calculated 263.08 kW, 1.745, 22.12%, and 67.8 $/GJ, respectively. At last, multi-variable regression analysis is used to obtain a correlation between key main performance criterion including ejector area ratio, ejector mass entrainment ratio, COP, exergy efficiency, and cost of cooling with vapor generator pressure, evaporator (I) temperature, evaporator (II) temperature, and condenser temperature.