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

This paper aims at providing a literature review on the recent development in ejectors, applications of ejector refrigeration systems and system performance enhancement. The paper presents useful guidelines regarding background and operating principles of ejector. A number of studies are reported and categorized in several topics including, refrigerant selections, mathematical modelling and numerical simulation of ejector system, geometric optimizations, operating conditions optimizations and combinations with other refrigeration systems. Most of the works that have been carried out recently are still limited to computer modelling, more experimental and large-scale work are needed in order to provide better understanding for the real industrial application.

Recent developments in ejector refrigeration technologies

https://hal.archives-ouvertes.fr/hal-00540588/document

CFD analysis of a supersonic air ejector. Part I: Experimental validation of single-phase and two-phase operation

A solar ejector cooling system using refrigerant R141b

Collector selection for solar ejector cooling system

A combined-cycle refrigeration system (CCRS) that comprises a conventional refrigeration and air-conditioning system using mechanical compressor (RAC/MC) and an ejector-cooling cycle (EJC) is proposed and studied. The EJC is driven by the waste heat from the RAC/MC and acts as the bottom cycle of the RAC/MC. A system analysis shows that the COP of a CCRS is significantly higher than a single-stage refrigeration system. Improvement in COP can be as high as 18.4% for evaporating temperature of the RAC/MC Te at −5°C. A prototype of the CCRS was built and tested in the present study. Experimental results show that at Te=−4.5°C, COP is improved by 14% for a CCRS. For Te at 5°C, COP can be improved by 24% for a CCRS with higher condensing temperature of the RAC/MC. The present study shows that the CCRS using the ejector-cooling cycle as the bottom cycle of the RAC/MC is viable. Further improvement in COP is possible since the prototype is not designed and operated at an optimal condition.

A combined-cycle refrigeration system using ejector-cooling cycle as the bottom cycle.

Publisher Summary This chapter presents the computer simulation results of an ejector cooling system (ECS). The refrigerants commonly used for ECS include R11, R12, R22, R113, R114, R123, R142b, and R134a. A solar ejector cooling system (SECS) essentially consists of an ECS and the solar collector. Solar thermal energy is absorbed by the solar collector and used to drive the ejector cooling machine. The ejector is the key component in the ejector refrigeration cycle. The computer simulation is further verified by experiments. The results so obtained exhibit that the solar ejector cooling system should be designed with a high-efficiency condenser and needs a medium-temperature solar collector. A low-cost specially designed single-glazed flat-plate solar collector with selective surface can fit this need.

V.A. Petrenko

Papers

A solar ejector cooling system using refrigerant R141b

Collector selection for solar ejector cooling system

A combined-cycle refrigeration system using ejector-cooling cycle as the bottom cycle.

A Study of Ejector Refrigeration System Design for Solar Cooling Application