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

Previous reviews on ejectors for expansion work recovery have provided detailed discussions of operating characteristics and control of ejector cycles, zero-dimensional ejector modeling, ejector geometry effects, and alternate ejector cycles. However, important advances in the field of ejector technology have occurred since previous reviews were written. Several focuses of recent ejector research are the development of multi-dimensional CFD ejector models, investigation of alternate ejector cycles and uses of the work recovered by the ejector, implementation of effective control strategies for ejector cycles, and application of ejectors in real systems. The objective of this paper is to present a review of developments in the use of ejectors for expansion work recovery in vapor-compression systems focusing on the past several years. Although the first commercial applications are being introduced to the market, it is suggested that future works continue in these areas in order to make ejectors more suitable for additional applications.

Review of recent developments in advanced ejector technology

Comparative study of two novel micro-CCHP systems based on organic Rankine cycle and Kalina cycle

Exergoeconomic analysis and multi-objective optimization of an ejector refrigeration cycle powered by an internal combustion (HCCI) engine

The present work reports a numerical analysis of a supersonic ejector in single-phase conditions using R134a as the working fluid. A numerical benchmark of some thermodynamic and two-equation turbulence models has been carried out to highlight the numerical model offering the best compromise between accuracy and calculation cost. The validation is achieved by comparing the predicted entrainment ratio with the experimental data of Garcia del Valle et al. (2014). The k−ω SST model together with the REFPROP 7.0 database equation appears to be the best combination to predict accurately the ejector performance and capture the shock wave structure. The influence of the outlet temperature, the discussion about the validity of some assumptions made by one-dimensional (1D) models and the exergy analysis within the ejector for the present operating conditions will later be discussed in Part 2 (Croquer et al., 2015).

Turbulence modeling of a single-phase R134a supersonic ejector. Part 1: Numerical benchmark

Energetic and exergetic comparison of basic and ejector expander refrigeration systems operating under the same external conditions and cooling capacities

This study aims to investigate distance education implementations in higher education of Turkey from 2010 to 2016 by numeric data. For this purpose, the numbers and distribution of students at vocational schools, undergraduate and graduate level programs being executed totally in distance education method were analyzed. While it was possible to reach to the numbers of distant students at vocational schools and undergraduate levels between 2010 and 2015, only 2014-2015 and 2015-2016 years’ data were been able to obtained at graduate level. Moreover, the change in the numbers of distant students by years was investigated. Hence it is a case study, it portrays the existing situation longitudinally. In this context, it is believed that the study will contribute to the actions targeting to open new distance education programs.

Analysis of distance education practices in higher education: the example of turkey

/pdf/yuksekogretimde-uzaktan-egitim-uygulamalarinin-incelenmesi-1rlbjf0ahk.pdf

Yükseköğretimde Uzaktan Eğitim Uygulamalarının İncelenmesi: Türkiye Örneği

/pdf/bir-cevrimici-ogrenim-destek-sisteminin-kullanilabilirlik-10gfpu5l96.pdf

Bir Çevrimiçi Öğrenim Destek Sisteminin Kullanilabilirlik Testi: Planlama, Uygulama, Değerlendirme

Utilisation of an ejector as an expander was experimentally investigated for an expansion work recovery in a basic refrigeration cycle. Exergy analysis was used to determine the amounts and locations of irreversibilities in the elements of the ejector expansion refrigeration system. It was seen that the ejector refrigeration cycle indicated a lower exergy destruction and a higher exergy efficiency compared to the vapour compression refrigeration cycle for each working condition. It was obtained that the values for the irreversibility of the ejector refrigeration cycle were less than in the vapour compression refrigeration cycle by 5.9-12.6% and the exergy efficiencies of ejector refrigeration cycle were 6.7-14.2% more than in the vapour compression cycle.

Halil Ersoy

Papers

Energetic and exergetic comparison of basic and ejector expander refrigeration systems operating under the same external conditions and cooling capacities

Analysis of distance education practices in higher education: the example of turkey

Yükseköğretimde Uzaktan Eğitim Uygulamalarının İncelenmesi: Türkiye Örneği

Bir Çevrimiçi Öğrenim Destek Sisteminin Kullanilabilirlik Testi: Planlama, Uygulama, Değerlendirme

An experimental investigation on exergy analysis of an ejector expansion refrigeration system