Historical and present developments of ejector refrigeration systems with emphasis on transcritical carbon dioxide air-conditioning applications

Elbel, Stefan

doi:10.1016/j.ijrefrig.2010.11.011

Cited by 170 publications

(70 citation statements)

References 18 publications

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“…Simultaneously, the smallest diffuser angle 5 o yielded the best ejector performance. Hence, both foregoing designed parameters can significantly influence the ejector performance (Elbel, 2011). The energy performance analysis indicated COP and cooling capacity improvement of the R744 transcritical ejector expansion cycle up to 7% and 8%, respectively, what confirmed the results presented in .…”

Section: The R744 Two-phase Ejector Technology In Refrigeration Systemsupporting

confidence: 81%

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Experimental analysis of the R744 vapour compression rack equipped with the multi-ejector expansion work recovery module

Haida

Banasiak

Smołka

et al. 2016

International Journal of Refrigeration

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Aim of this thesis is to present an experimental investigation of standard R744 supermarket refrigeration system, with the high-pressure electronic valve (HPV), and refrigeration system with multi-ejector expansion pack on the same vapour compression rack. Comparison of the R744 multi-ejector refrigeration system, was carried out based on energy performance characteristics: refrigeration capacity, power consumption, COP, and exergy efficiency. Apart from the system performance comparison, influence of the pressure level in the flash tank on the system performance for both alternatives was analysed.The experimental results indicated COP and exergy efficiency improvement of the multiejector refrigeration system up to 7% and 13.7%, respectively. The multi-ejector system was able to operate in smaller range of the tanks pressure lift than the standard system dependent on the refrigeration load and the exit gas cooler section parameters. The highest values of COP and exergy efficiency were obtained by the multi-ejector refrigeration system for the tanks pressure lift value close to the limit value. The values of the overall compressor efficiencies were significantly differentiated, dependent on the operation module (cooling load and heat rejection conditions), which strongly influenced the values of COP and exergy efficiency. Therefore, it was not possible to clearly define the optimum pressure in the flash tank. It was concluded that improvement of compressors efficiencies utilized in the multiejector system will indicate high energy performance of the refrigeration system.

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Section: The R744 Two-phase Ejector Technology In Refrigeration Systemsupporting

confidence: 81%

“…Norman Gay patented refrigeration system with applied two phase ejector (Elbel, 2011). The two phase ejector characterizes two-phase flow outside the ejector, where the driving flow and driven flow are in liquid and vapor phase, respectively.…”

Section: The R744 Two-phase Ejector Technology In Refrigeration Systemmentioning

confidence: 99%

Experimental analysis of the R744 vapour compression rack equipped with the multi-ejector expansion work recovery module

Haida

Banasiak

Smołka

et al. 2016

International Journal of Refrigeration

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“…Figure 7 presents the values of the relative errors between the model predictions and the experimental results for the critical mass flux. It can be seen that HEM tends to underpredict the critical mass flux, which is consistent with the published literatures [23,24]. This phenomenon is mainly because the homogeneous flow assumption neglects possible flashing delays caused by metastability [28,29], which results in the largest possible amount of vapor in the nozzle throat.…”

Section: Mass Flow Ratesupporting

confidence: 89%

“…Elbel et al [23] investigated the critical mass flux of the convergingdiverging motive nozzle in the R744 ejector expansion refrigeration systems, and found that the deviations of the HEM predictions and the Henry-Fauske model predictions from the experimental mass flow rates are −10% ~ −20% and −5% ~ −10% respectively. Kornhauser and Harrell [24] found that the deviations of the experimental mass flow rate values from the HEM predictions are about 10% in their R134a ejector expansion refrigeration systems.…”

Section: Introductionmentioning

confidence: 99%

Choked Flow Characteristics of Subcritical Refrigerant Flowing Through Converging-Diverging Nozzles

Zhang

Tian

Tong

et al. 2014

Entropy

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This paper presents the experimental results the choked flow characteristics of a subcritical refrigerant through a converging-diverging nozzle. A test nozzle with a throat diameter of 2 mm was designed and developed. The influence of operating conditions on the choked flow characteristics, i.e., the pressure profile and mass flow rate under choked flow conditions are investigated. The results indicate that the choked flow occurs in the flow of subcritical refrigerant through nozzles under the normal working conditions of air-conditioners or heat pumps. The pressure drop near the throat is about 80% of the total pressure drop through the nozzle. The critical mass flux is about 19,800 ~ 24,000 kg/(s·m 2 ). The critical mass flow rate increases with increasing the upstream pressure and subcooling. Furthermore, the relative errors between the model predictions and the experimental results for the critical mass flux are also presented. It is found that the deviations of the predictions for homogeneous equilibrium model and Henry-Fauske model from the experimental values are −35% ~ 5% and 15% ~ 35%, respectively.

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“…However, the reference transcritical CO 2 refrigeration cycle suffers from the defect of its low energy efficiency due to the large throttling loss [1]. This loss can be reduced by using a two-phase ejector to replace the throttling valve [2]. A two-phase ejector utilizes the expansion work to lift the suction pressure of the compressor so as to enhance the performance of the refrigeration cycle.…”

mentioning

confidence: 99%

Effect of Suction Nozzle Pressure Drop on the Performance of an Ejector-Expansion Transcritical CO2 Refrigeration Cycle

Zhang

Tian

2014

Entropy

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Abstract:The basic transcritical CO 2 systems exhibit low energy efficiency due to their large throttling loss. Replacing the throttle valve with an ejector is an effective measure for recovering some of the energy lost in the expansion process. In this paper, a thermodynamic model of the ejector-expansion transcritical CO 2 refrigeration cycle is developed. The effect of the suction nozzle pressure drop (SNPD) on the cycle performance is discussed. The results indicate that the SNPD has little impact on entrainment ratio. There exists an optimum SNPD which gives a maximum recovered pressure and COP under a specified condition. The value of the optimum SNPD mainly depends on the efficiencies of the motive nozzle and the suction nozzle, but it is essentially independent of evaporating temperature and gas cooler outlet temperature. Through optimizing the value of SNPD, the maximum COP of the ejector-expansion cycle can be up to 45.1% higher than that of the basic cycle. The exergy loss of the ejector-expansion cycle is reduced about 43.0% compared with the basic cycle.

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Historical and present developments of ejector refrigeration systems with emphasis on transcritical carbon dioxide air-conditioning applications

Cited by 170 publications

References 18 publications

Experimental analysis of the R744 vapour compression rack equipped with the multi-ejector expansion work recovery module

Experimental analysis of the R744 vapour compression rack equipped with the multi-ejector expansion work recovery module

Choked Flow Characteristics of Subcritical Refrigerant Flowing Through Converging-Diverging Nozzles

Effect of Suction Nozzle Pressure Drop on the Performance of an Ejector-Expansion Transcritical CO2 Refrigeration Cycle

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