Performance study of an enhanced ejector refrigeration cycle with flash tank economizer for low-grade heat utilization

This paper presents an enhanced ejector refrigeration cycle (EERC) by introducing a flash tank economizer and an auxiliary ejector to improve the performance of a conventional ejector refrigeration cycle (CERC). The proposed cycle could increase the overall entrainment ratio of the ejectors, the cycle cooling capacity and COP due to reduction of flash gas delivered to the evaporator. Thermodynamic performances of the EERC using R134a and R600a are evaluated in detail and compared with those of the CERC using the thermodynamic first law. Calculation results show that there is an optimal inlet temperature of flash tank economizer in EERC. The maximum COPs of EERC with R134a and R600a increase by 10.7% and 9.9% compared to the CERC, respectively. Also, the cooling capacities of EERC have the same improvement values. Furthermore, the EERC shows better performances under a higher evaporating temperature. The obtained results indicate that the EERC would be beneficial to the development of ejector refrigeration technology.