Performance Evaluation of Triple-evaporator Ejector Refrigeration Cycle (TEERC) for Various Applications, Using Low-temperature Heat Sources

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 (R717, R152a, R134a, R290, cis-2-butene, butane, isobutene, isobutane, R236fa) are presented for the propo cycle based on the working fluid characteristics, cycle efficiency, and environmental consideration. Energetic and exergetic an alyses of the proposed cycle have been performed leading to determination of the main source of the irreversibility of the whole cycle. It was found that generator has the main source of irreversibility which is followed by the ejector and condenser, respectively. The maximum coefficient of performance (COP) obtained for R717 by the value of 0.333 and the minimum COP calculated for R236fa by the value of 0.268. On the other hand, the maximum and minimum exergy efficiencies are calculated for R717 and isobutene by the values of 21.04 and 11.93 %, respectively. At last, sensitivity analysis of some key components 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. More ever, among all influential parameters, ejector mass entrainment ratio has a stronger effect on the freezing, ventilation, and cooling capacities.

Keywords:

Triple-evaporator ejector refrigeration cycle (TEERC) , Cooling , Freezing , Ventilation , Energetic analysis , Exergetic analysis , Working fluid selection , Low- temperature heat