The increasing need for thermal comfort has led to a rapid increase in the use of cooling systems and, consequently, electricity demand for air-conditioning systems in buildings. Heat-driven ejector refrigeration systems appear to be a promising alternative to the traditional compressor-based refrigeration technologies for energy consumption reduction. This paper presents a comprehensive literature review on ejector refrigeration systems and working fluids. It deeply analyzes ejector technology and behavior, refrigerant properties and their influence over ejector performance and all of the ejector refrigeration technologies, with a focus on past, present and future trends. The review is structured in four parts. In the first part, ejector technology is described. In the second part, a detailed description of the refrigerant properties and their influence over ejector performance is presented. In the third part, a review focused on the main jet refrigeration cycles is proposed, and the ejector refrigeration systems are reported and categorized. Finally, an overview over all ejector technologies, the relationship among the working fluids and the ejector performance, with a focus on past, present and future trends, is presented.

https://re.public.polimi.it/bitstream/11311/984261/1/2016_RSER_BesagniMereuInzoli.pdf

Ejector refrigeration: A comprehensive review

This paper provides a literature review on ejectors and their applications in refrigeration. A number of studies are grouped and discussed in several topics, i.e. background and theory of ejector and jet refrigeration cycle, performance characteristics, working fluid and improvement of jet refrigerator. Moreover, other applications of an ejector in other types of refrigeration system are also described.

Ejectors: applications in refrigeration technology

One-dimensional ejector analyses often use coefficients derived from experimental data for a set of operating conditions with limited functionality. In this study, several ejector designs were modelled using finite volume CFD techniques to resolve the flow dynamics in the ejectors. The CFD results were validated with available experimental data. Flow field analyses and predictions of ejector performance outside the experimental range were also carried out. During validation, data from CFD predicted the entrainment ratios with greater accuracy on definite area ratios, although no shock was recorded in the ejector. Predictions outside the experimental range—at operating conditions in a combined ejector–vapour compression system—and flow conditions resulting from ejector geometry variations are discussed. It is found that the maximum entrainment ratio happens in the ejector just before a shock occurs and that the position of the nozzle is an important ejector design parameter.

CFD analysis of ejector in a combined ejector cooling system

Solar cooling is a good example of addressing climate changes. In this paper, we provide overviews for working principles of solar thermally operated cooling technologies and reviews for advancements of such technologies from the most recent publications. Researches of solar absorption cycles investigated new refrigerant–absorbent pairs and various system configurations that could lead to increasing solar fraction and extending the cycle operation. Researches of solar adsorption cycles focused on the development and testing of various adsorbent–refrigerant pairs, improving cycle components, and increasing the system efficiency. For the ejector cycles, many studies focused on using computer models and experimental works to investigate the performance of the ejector and find the key parameters affecting its operation. Although many researches have conducted for solar thermal cooling technologies, their overall efficiencies are lower than that of the vapor compression cycles. Therefore, improving efficiency of solar thermally operated cooling technologies is an essential future research topic.

Review of solar thermal air conditioning technologies.

Use of solar energy to produce refrigeration and air conditioning can be a viable option to replace conventional cooling systems. Research and development activities on solar cooling systems started in the 1970s because of the energy crisis and has picked up again in the past few years due to greater awareness of the necessity to reduce emission of greenhouse and Ozone depletion gases. Although, most of the attention in the past has been on using solar heat to run absorption refrigeration systems, solar thermo-mechanical cooling systems have received a renewed attention in recent years due to the advantages such as, ability to produce low refrigeration temperatures ( This paper reviews the important developments in thermo-mechanical solar cooling technologies. An overview of different solar cooling technologies and a detailed literature survey of published studies on the design and analysis, experimental setups and enhancement approaches for thermo-mechanical solar cooling systems are presented. Findings from studies considering system configurations, working fluids, operational conditions, and performance indicators have been summarized in tables for easy comparison. Finally, various system configurations are presented schematically with additional information on each design.

N.A. Shchetinina

Papers

Collector selection for solar ejector cooling system