Hybrid Thermally Driven Sorption–Ejector Systems: A Comprehensive Overview

The rapid increase in population and demand for human comfort causes a substantial increase in energy usage. Sorption technology and ejectors are the most concerned heat-driven system nowadays due to their low energy consumption, ability to be powered by a low-grade heat source, and environmental friendliness. However, it has low energy efficiency and a high initial cost compared with vapor compression cycles. Combining sorption–ejector systems can increase the overall thermal performance, provide the benefits of each cycle, and overcome the limitations of a single cycle. This study provides a comprehensive overview of the art of combining sorption, including absorption and adsorption, with ejector systems. The paper primarily focuses on the theory of operation and the background of absorption, adsorption, and ejector systems. Research and achievements on combined absorption–ejector systems are classified into combined single-ejector, multi-ejector, and other systems with absorption cooling systems. On the other hand, studies on adsorption–ejector systems are classified into combined adsorption cooling, adsorption desalination, and other systems with ejectors. A summary of the reviewed studies and the utilized working fluid is provided and discussed. Results showed that numerous experimental studies still need to be conducted to validate the theoretical data. At different design and operating conditions and system design, by using combined sorption–ejector systems, the power consumption can be decreased by 9.8%, cooling capacity reduced by 13.6%, and the coefficient of performance can be enhanced by 8–60% compared with the standalone sorption system. The overall COP of combined adsorption–ejector systems increased by 0.33 and 1.47 compared with the standalone ABCS, which is lower than that obtained from EJABS. The SDWP is enhanced by 51% compared with the standalone ADCS. The combined adsorption–ejector systems are compatible with several working fluids; however, LiBr-H₂O solution predominates.