Performance Evaluation of Novel Advanced Recompression Absorption Refrigeration Systems Equipped with Ejector and Vapor Injection Technology

Abstract

The absorption refrigeration cycle (ARC) faces challenges considering its decreased working pressure and COP. By integrating Recompression technology (RAC) into ARC, these issues are partly addressed. To address these inefficiencies, in this study, ejector and vapor injection techniques are incorporated into refrigerant side of the RAC cycle, resulting in the development of advanced systems: Refrigerant ejector enhanced recompression absorption cycle (RE-RAC) and Vapor injection enhanced recompression absorption cycle (VI-RAC). Key metrics assessed are 1st and 2nd law efficiency, system exergy destruction rate, compressor load, and generator heat requirements. Conclusively, under analogous operating conditions, RE-RAC and VI-RAC demonstrate a substantial improvement in COP, achieving 76 % and 63 % enhancements, respectively, over the standard RAC system. Compared to the conventional solution ejector-based SE-RAC, these systems show performance increases of 28 % and 19 %, respectively. The findings also highlight the sensitivity of these systems to parameters such as generator temperature and pressure, evaporator temperature, absorber temperature, evaporator recovery and normal pressure ratio. At higher evaporator temperature and lower generator temperature, the performance of these systems as well as enhancement of RE-RAC over VI-RAC is higher observed. The optimal value of generator pressure and recovery pressure ratio for maximum efficiency and minimum total exergy destruction rate is also dependent upon these. At a generator temperature of 67 °C and an evaporator temperature of 8 °C, RE-RAC exhibits a 35 % higher COP compared to VI-RAC. However, at −10 °C evaporator temperature, changes in external generator heat input and compressor work reduce the COP enhancement to 5 %.