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

Sağ, Nagihan Bilir; Ersoy, H. Kursad; Hepbaşlı, Arif; Halkacı, Hüseyin Selçuk

doi:10.1016/j.enconman.2014.11.023

Cited by 98 publications

(16 citation statements)

References 35 publications

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“…Ersoy and Bilir Sag [187] tested a R124a EERS and, depending on the operating condition, the COP was 6.2-14.5% higher than that of the conventional system. Bilir Sag et al [182] (experimental study using R134a) reported an increase of COP by 7.34-12.87% and an increase of the exergy efficiency of 6.6-11.24% compared to a conventional system. An EERS provide performance enhancement due to two effects: the liquid-fed evaporator and work recovery.…”

Section: Ejector Expansion Refrigeration System (Eers)mentioning

confidence: 99%

Ejector refrigeration: A comprehensive review

Besagni

Mereu

Inzoli

2016

Renewable and Sustainable Energy Reviews

414

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a b s t r a c tThe 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.

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Section: Ejector Expansion Refrigeration System (Eers)mentioning

confidence: 99%

Ejector refrigeration: A comprehensive review

Besagni

Mereu

Inzoli

2016

Renewable and Sustainable Energy Reviews

414

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“…Li et al [19] investigated the performance of an EEC using R1234yf and R134a and found that the R1234yf EEC has lower COP and volumetric cooling capacity (VCC), but it offers greater COP and VCC improvement potential compared with that of R134a EEC. Bilir et al [20] experimentally found that the use of an ejector in place of the throttle valve in a R134a refrigeration cycle will improve the COP and exergy efficiency by 7.34%-12.87% and 6.6%-11.24%, respectively, under the same external operating conditions. Lawrence and Elbel [21] conducted an experimental investigation of EEC that can provide multiple evaporation temperatures, and found that the cycle showed maximum COP improvements of 12% with R1234yf and 8% with R134a compared with a two evaporation temperatures basic cycle.…”

Section: Introductionmentioning

confidence: 99%

Energetic and Exergetic Analysis of an Ejector-Expansion Refrigeration Cycle Using the Working Fluid R32

Zhang

Tong

Chang

et al. 2015

Entropy

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Abstract:The performance characteristics of an ejector-expansion refrigeration cycle (EEC) using R32 have been investigated in comparison with that using R134a. The coefficient of performance (COP), the exergy destruction, the exergy efficiency and the suction nozzle pressure drop (SNPD) are discussed. The results show that the application of an ejector instead of a throttle valve in R32 cycle decreases the cycle's total exergy destruction by 8.84%-15.84% in comparison with the basic cycle (BC). The R32 EEC provides 5.22%-13.77% COP improvement and 5.13%-13.83% exergy efficiency improvement respectively over the BC for the given ranges of evaporating and condensing temperatures. There exists an optimum suction nozzle pressure drop (SNPD) which gives a maximum system COP and volumetric cooling capacity (VCC) under a specified condition. The value of the optimum SNPD mainly depends on the efficiencies of the ejector components, but is virtually independent of evaporating temperature and condensing temperature. In addition, the improvement of the component efficiency, especially the efficiencies of diffusion nozzle and the motive nozzle, can enhance the EEC performance.

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“…At the maximum injection fraction considered (X inj = 10%) a reduction of ∼8% is observed for both quantities. These results show that the injection of droplets effectively attenuates the shock wave intensity in the CAS, thus affecting one of the main sources of irreversibilities inside the ejector [12,22]. At the maximum injected fraction considered, the entropy generation between sections L5 and L7 is reduced by 10% relative to the case without injection.…”

Section: Shock Intensitymentioning

confidence: 58%

“…The exergy destruction index ξ i compares the exergy destroyed within a specific region of the ejectorḊ i to the total exergy destroyed through the deviceḊ ej [12]:…”

Section: Exergy Destruction Indexmentioning

confidence: 99%

“…Therefore, three other parameters have been considered in this study to better reflect these differences: the ejector efficiency η Elbel as proposed by Elbel and Hrnjak [11], which gives insight on the efficiency of the ejector as a compression device; the exergy efficiency η χ , which compares the exergy output relative to the sum of the primary and secondary inlets and the ejector efficiency and the exergy destruction coefficient ξ i , which reflects the distribution of exergy destruction through the device [12]. These parameters are defined in Section 4.7.…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic Modelling of Supersonic Gas Ejector with Droplets

Croquer

Poncet

Aidoun

2017

Entropy

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This study presents a thermodynamic model for determining the entrainment ratio and double choke limiting pressure of supersonic ejectors within the context of heat driven refrigeration cycles, with and without droplet injection, at the constant area section of the device. Input data include the inlet operating conditions and key geometry parameters (primary throat, mixing section and diffuser outlet diameter), whereas output information includes the ejector entrainment ratio, maximum double choke compression ratio, ejector efficiency, exergy efficiency and exergy destruction index. In single-phase operation, the ejector entrainment ratio and double choke limiting pressure are determined with a mean accuracy of 18% and 2.5%, respectively. In two-phase operation, the choked mass flow rate across convergent-divergent nozzles is estimated with a deviation of 10%. An analysis on the effect of droplet injection confirms the hypothesis that droplet injection reduces by 8% the pressure and Mach number jumps associated with shock waves occuring at the end of the constant area section. Nonetheless, other factors such as the mixing of the droplets with the main flow are introduced, resulting in an overall reduction by 11% of the ejector efficiency and by 15% of the exergy efficiency.

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

Cited by 98 publications

References 35 publications

Ejector refrigeration: A comprehensive review

Ejector refrigeration: A comprehensive review

Energetic and Exergetic Analysis of an Ejector-Expansion Refrigeration Cycle Using the Working Fluid R32

Thermodynamic Modelling of Supersonic Gas Ejector with Droplets

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