Performance optimization study on R290/R1233zd(E) in a variable temperature heat source ejector refrigeration cycle

In this paper, a new strategy for optimizing the ejector refrigeration system is proposed, and a thermodynamic model with the non-azeotropic mixed refrigerant R290/R1233zd(E) under variable temperature heat source is established. The influences of the temperature slip of R290/R1233zd(E) and the temperature change of cold and heat source of the heat exchanger on the performance of the heat exchanger and ejector refrigeration system are analysed by numerical simulation. The results show that compared with the single working fluid, the mixed working fluid can increase the inlet temperature of working fluid and injection fluid, optimize system performance, and R290/R1233zd(E) (mass fractions of 0.7 and 0.3, respectively) is the optimal mixed working fluid for this system. Compared with the single working fluid R1233zd(E), the coefficient of performance of the mixed working fluid system increases by 44% and the system exergy efficiency increases by 39%. The optimal mass fraction of R290/R1233zd(E) increases with the increase of the cooling water outlet temperature in the condenser, and decreases with the increase of the cooling water inlet temperature in the condenser. Due to the influence of the pinch point position, the relationship between the generator exergy loss and the condenser exergy loss is different for mixed working fluids with different temperature slips. The injector exergy loss and generator exergy loss first increase and then decrease with the increase of temperature slip, while the condenser exergy loss first decreases and then increases with the increase of temperature slip.