Multi-objective optimization and 3E analysis for solar-driven dual ejector refrigeration and phase change material as thermal energy storage

Abstract

Ejector refrigeration cycles have garnered attention due to their inherent advantages, including simplicity, the ability to leverage low-temperature energy sources, and reduced reliance on high electrical power requirements. Optimizing these systems becomes pivotal, given the inherent challenges of low efficiency in ejector refrigeration cycles. This study explores an ejector refrigeration cycle incorporating a secondary ejector to recover expansion energy from the condenser. Solar collectors provide the necessary heat for the cycle, utilizing phase change materials for thermal storage. Initially, the impact of five key parameters, generator temperature, condenser temperature, evaporator temperature, collector area, and storage tank volume, on the cycle's performance is thoroughly investigated. Subsequently, a three-objective optimization is executed, resulting in optimal values for the mentioned parameters: 83.4 °C for the generator temperature, 35.8 °C for the condenser temperature, 6.8 °C for the evaporator temperature, 82 m2 for the collector area, and 4 m3 for the storage tank volume. The analysis of energy, exergy and exergeoeconomics for the optimal point showed that the exergy efficiency for the ejector and solar cycle is 6.78 % and 10.74 %, respectively. Also, the COP of the refrigeration cycle was obtained as 0.1858. The results showed that the solar fraction is equal to 65.4 %, and the highest amount of exergy destruction is related to solar collectors, which is equal to 8.136 kW.