• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.890-894
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• 2015

Recently, research on high-efficiency refrigeration cycles that apply an ejector to basic cycles has progressed actively. The role of the ejector and the performance of refrigeration cycles are subordinate to ejector locations. In this study, the performance of three refrigeration cycles with different ejector locations is compared and analyzed. The results showed an increased COP in all cycles due to the application of the ejector, with the highest increase of 44% compared to a basic refrigeration cycle. The ejector refrigeration cycle proposed in this study presents the highest COP, 3.47. Moreover, the decrease in condensation capacity in Bergander's cycle, Xing's cycle, and our proposed ejector refrigeration cycle went up to 21%. In refrigeration cycles applying the ejector, the pressure ratio of the ejector, the vapor fraction of discharge, and compression ratio are important factors for COP enhancement. For this reason, detailed and accurate control of these is significant.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.8
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• pp.946-952
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• 2005

The $CO_{2}$ refrigeration cycle is expected to reduce the compressor work and increase the COP by applying two-phase ejector as a device for the recovery of dissipated expansion energy. In this study, the performance of the cycle was simulated and effects of the ejector shapes on the performance of the $CO_{2}$ refrigeration cycle were investigated. The following results were obtained through the cycle simulation. The COP of the $CO_{2}$ refrigeration cycle with two-phase ejector flow which expansion is occured in the isentropic manner is increased by a maximum of 24 $\%$ than the basic cycle with expansion valve If the velocity nonequilibrium in the mixing process is assumed the COP of the cycle is increased with the increase of the length and the decrease of the section area of the mixing tube. The best cycle performance is obtained when the divergent angle of diffuser is 7.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.7
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• pp.362-368
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• 2015

This paper presents a numerical study on the performance of a vapor compression cycle equipped with an ejector as an expansion device to improve the COP by reducing the expansion loss and compressor work. The simulation is carried out using a model based on the conservation of mass, energy and momentum in the ejector. From the results of the simulation, the vapor compression cycle equipped with an ejector showed a maximum COP improvement of 14.0% when using R134a refrigerant and 16.8% when using R1234yf. In addition, the performance of the system with an ejector represents the increased performance as the temperature difference between condensing and evaporating increased.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.2
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• pp.147-154
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• 2012

Recently, many researchers have studied the performance of the transcritical $CO_2$ refrigeration cycle in order to improve the system efficiency. In this study, the length of IHX in the $CO_2$ ejector cycle was varied so as to evaluate the performance improvement. As a result, compressor work and cooling capacity was increased by 3% and 5% as the length of internal heat exchanger was changed from 3 m to 15 m. The best COP was appeared at internal heat exchanger length of 12 m, and it was 3.01. Besides, the length of internal heat exchanger has a big effect to pressure lift ratio and entrainment ratio in the ejector $CO_2$ cycle and it may be changed with operating conditions and system specifications.

• Journal of Power System Engineering
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• v.21 no.1
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• pp.24-29
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• 2017

Studies in liquid-vapor ejector, which performs a great efficiency in refrigeration cycle is highly concerned. This paper is based on basic refrigeration cycle and three ejector refrigeration cycles and the comparison and contrasts about when 6 different refrigerants are applied to such refrigeration cycles. All cycles had a percentage increase of COP from 4 to 74% when ejector was applied, and the source of increasement was the decrease of total work done due to ejector's pressure recovery function. When R-245fa is applied to cycle (d), results showed that COP was the most superior in such cycle, R-245fa showed high volume entrainment ratio in all cycles. Future studies in refrigeration cycles will require more knowledge and experiments on ejector's appliance to refrigeration cycles and the actuation of such functions.