Energy analysis and performance evaluation of a novel multi-evaporator ejector refrigeration cycle (ERC)

This paper presents a theoretical analysis of triple-evaporator ejector refrigeration cycle (TEERC) for triple applications of cooling, freezing, and ventilation, based upon the first and second laws of thermodynamics. Nine appropriate working fluids (i.e., R717, R152a, R134a, R290, cis-2-butene, butane, isobutene, isobutane, R236fa) are presented for the proposed cycle based on the working fluid characteristics, cycle efficiency, and environmental consideration. Energetic and exergetic analyses of the proposed cycle have been performed leading to the determination of the main source of the irreversibility of the whole cycle. It was found that the generator has the main source of irreversibility which is followed by the ejector and condenser, respectively. The maximum and minimum coefficients of performance (COP) are obtained for R717 and R236fa by the values of 0.333 and 0.268, respectively. On the other hand, the maximum and minimum exergy efficiencies are calculated for R717 and isobutene by the values of 21.43% and 12/51 %, respectively. Also, using R717 as the best working fluid in this investigation, the ventilation, cooling and freezing capacities are obtained 11.68 kW, 3.86 kW, and 1.904 kW, respectively. At last, sensitivity analysis of some key parameters has been conducted in order to understand the characteristics of the proposed cycle, comprehensively. It has been shown that increasing of the evaporators and generator temperatures and decreasing of the condenser temperature increase both COP and exergy efficiency. Moreover, among all influential parameters, the ejector mass entrainment ratio has a stronger effect on the freezing, ventilation, and cooling capacities.