Marzie Babaie Rabiee

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 temperatures. The refrigerant (NH3) 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, 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, subcooler 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 NH3-H2O as the working fluid. Additionally, the system's 3.5-year payback period underscores its cost-effectiveness.