Energy and exergy analysis of a high-efficiency multi-evaporator absorption refrigeration system with integrated ejectors and compression cooling system

Abstract

• A novel absorption-compression cooling system was designed and analyzed. • The system is equipped with compression-ejector and absorption-ejector cycles. • Optimization results showed that COP increased by 160 % and ECOP by 33 %. • Sub-coolers boost COP by 43 % and cut exergy destruction by 30 %. • The design has a payback period of 3.5 years. Global warming has created severe challenges in the cooling crisis, highlighting the urgent need to design and enhance the efficiency of standard cooling systems such as absorption refrigeration systems (ARS). The primary purpose of this study is the design and performance enhancement of an ARS, a widely used cooling method. A novel hybrid cycle combining a compression-ejector cycle with two evaporators and an absorption-ejector cycle is proposed to achieve both above- and sub-zero evaporator temperatures. The refrigerant (NH 3 ) from the generator is compressed, and part of the heat generated is reused to meet the generator’s heat demand, eliminating the condenser and reducing heat loss. Two sub-cooler heat exchangers are incorporated to enhance efficiency, significantly boosting performance. The effects of key parameters such as generator temperature and pressure, evaporator temperature, ejector geometry, cooling load, and heat exchanger efficiency on the coefficient of performance (COP) and exergetic efficiency (ECOP) are analyzed. Optimization results show the proposed system achieves up to 160 % COP improvement and 33 % ECOP enhancement. Additionally, sub-cooler heat exchangers can increase the COP by 43 % and decrease the exergy destruction by 30 %. Including a gas–liquid ejector expands the generator temperature range, enabling higher COP at lower temperatures. This design addresses the challenges of high activation temperature and pressure in ARSs with NH 3 -H 2 O as the working fluid. Additionally, the system’s 3.5-year payback period underscores its cost-effectiveness.