Thermodynamic Analysis of an Ejector Assisted Two-Stage Vapour Compression Refrigeration System

Abstract

In this article, a novel two-stage ejector-assisted vapour compression refrigeration (TSEVCR) system is conceived by
integrating an ejector expansion vapour compression refrigeration (EVCR) cycle with a two-stage vapour compression refrigeration system using a flash intercooler (FIC) for sub-zero temperature applications. A performance comparison is conducted between the two-stage vapour compression refrigeration system (TSVCR) and the TSEVCR with flash intercooling, using propane (R290), isobutane (R600a), and R1234yf as refrigerants. I^st law and II^nd law analyses of the TSVCR and TSEVCR system are accomplished for a range of condenser temperature (T_cndr = 30°C to 55°C), evaporator temperature (T_evpr = –45°C to –20°C), and pressure drop (δP = 1 kPa to 50 kPa) in the suction chamber. Variations in performance parameters such as coefficient of performance (COP_TSEVCR) & % improvement in COP_TSEVCR (%COP_{TSEVCR, imp}), optimum intermediate pressure (P_{int, opt}), pressure lift factor (PLF), improvement in pressure ratio (% r_{p, imp}), total exergy destruction (E_{d, total}), and exergetic efficiency (η_exergetic) of both the systems for the above range of the operating parameters are reported in this study. The results show that at T_cndr = 30°C and T_evpr = –20°C, R600a yields the maximum COP_TSEVCR of 3.95, whereas R1234yf gives the highest % COP_{TSEVCR, imp} of 5.59%, and PLR = 1.081, compared to the other two refrigerants. Additionally, the II^nd law analysis reveals that at T_cndr = 55°C and T_evpr = –45°C, R290 yields the maximum E_{d, total} of 53.77 kW, whereas R1234yf achieves the highest η_exergetic of 58.94%.