• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1548-1554
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• 2013

This paper presents the analysis on performance characteristics of R744-R410A cascade refrigeration system to offer the basic design data for the operating parameters of this system. The performance of cascade refrigeration system is analyzed by using EES program. The operating parameters include compressor efficiency, and condensing and evaporating temperature in R410A high- and R744 low-temperature cycle, respectively. The COP of this system increases with the decrease of condensing temperature, and increases with the increasing evaporating temperature. And the COP of this system increases with the compression efficiency. Therefore, it can be seen that the compression efficiency, and evaporating and condensing temperature of R744-R410A cascade refrigeration system have an effect on the COP of this system. Also, it can be known that the cascade evaporation temperature with the highest efficiency in each parameter is present. Thus, it is an important to design R744-R410A cascade refrigeration system by considering these parameters.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1427-1433
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• 2012

In this paper, cycle performance analysis of cascade refrigeration system using alternative FREON refrigerants and natural refrigerants are presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include subcooled and superheated degree, and condensing and evaporating temperature, temperature difference of cascade heat exchanger in cascade refrigeration system. The COP of cascade refrigeration system increases with the increasing subcooled degree, but there is no significant changes with the increasing superheated degree. The COP of cascade refrigeration system depends on evaporating and condensing temperatures of cascade heat exchanger. Therefore, subcooled degree, evaporating and condensing temperature of cascade heat exchanger using alternative FREON refrigerants and natural refrigerants have an effect on the COP of this system. In this paper, COP of cascade refrigeration system using (R23 / R290), (R23 / R600), (R23 / R600a), (R23 / R717), (R744 / R404A) are higher 20 ~ 36 % than (R23 / R22), using R23 for low temperature system and R22 for high temperature system.

• Journal of the Korean Institute of Gas
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• v.14 no.1
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• pp.1-7
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• 2010

In this paper, cycle performance analysis of $NH_3-CO_2$(R717-R744) two-stage cascade refrigeration system is presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include subcooling and superheating degree, compressor efficiency, and condensing and evaporating temperature in the ammonia(R717) high temperature cycle and the carbon dioxide low temperature cycle. The main results were summarized as follows : The COP of two-stage cascade refrigeration system increases with the increasing subcooling degree, but decreases with the increasing superheating degree. The COP of two-stage cascade refrigeration system decreases with the increasing condensing temperature, but increases with the increasing evaporating temperature. And the COP of two-stage cascade refrigeration system increases with increasing the compressor efficiency. Therefore, superheating and subcoolng degree, compressor efficiency, and evaporating and condensing temperature of $NH_3-CO_2$(R717-R744) two-stage cascade refrigeration system have an effect on the COP of this system.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.34 no.2
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• pp.23-27
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• 2005

기존 증기압축식 냉동시스템에 이젝터를 장착하여 시스템 효율을 향상시키는 여러 가지 방안과 상용화된 Denso 이젝터 시스템에 대해 소개하고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.10
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• pp.2565-2571
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• 2009

In this paper, cycle performance analysis of cascade refrigeration system using $NH_3-CO_2$(R717-R744) is presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include subcooling and superheating degree and condensing and evaporating temperature in the ammonia(R717) high temperature cycle and the carbon dioxide low temperature cycle. The COP of cascade refrigeration system increases with the increasing superheating degree, but decreases with the increasing subcooling degree. The COP of cascade refrigeration system increases with the increasing condensing temperature, but decreases with the increasing evaporating temperature. Therefore, superheating and subcoolng degree, evaporating and condensing temperature of cascade refrigeration system using $NH_3-CO_2$ have an effect on the COP of this system. A multilinear regression analysis was employed in terms of subcooling, superheating, evaporating, condensing, and cascade heat exchanger temperature difference in order to develop mathematical expressions for maximum COP and an optimum evaporating temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.7
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• pp.564-571
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• 2001

The present study investigated the effect of key parameters on the performance of a cascade system using R-22 and R-23 refrigerants. Experimental data for the cascade system have been compared with simulation results using thermodynamic analysis. The cascade system tested at the evaporating temperature of $-80^{\circ}C $ and the condensing temperature of$40^{\circ}C $. The key experimental parameters were the evaporating temperature of the HTC(-35, -30, -25, -20, $-15^{\circ}C $) and mass flux of the HTC(200, 250, 300kg/$m^2$s). As the evaporating temperature and the mass flux of the HTC were increased respectively, the COP and the refrigerating efficiency were increased and then decreased while the volume flow rate per unit refrigeration capacity showed the opposite trend. The maximum COP and refrigerating efficiency were obtained at the evaporating temperature of the HTC of $-25^{\circ}C $ and the mass flux of 250 kg/$m^2$s.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.1
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• pp.73-79
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• 2011

In this paper, cycle performance analysis of cascade refrigeration system using alternative FREON refrigerants are presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include subcooled and superheated degree, and evaporating and condensing temperature, temperature difference of cascade heat exchanger in cascade refrigeration system. The COP of cascade refrigeration system increases with the increasing subcooled degree, but there is no significant changes with the increasing superheated degree. The COP of cascade refrigeration system depends on evaporating and condensing temperatures of cascade heat exchanger. Therefore, subcooled degree, evaporating and condensing temperature of cascade heat exchanger using alternative FREON refrigerants have an effect on the COP of this system. In this paper, COP of cascade refrigeration system using R23 for low temperature system and R507A for high temperature system is higher 8 ~ 29 % than using R13 for low temperature system and R22 for high temperature system.

• Proceedings of the SAREK Conference
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• 2007.06a
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• pp.26-26
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• 2007

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.769-774
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• 2003

In this paper, the performance of a domestic Kim-Chi refrigerator is predicted by using a calculation model & experiment. The objectives of this study are to find out the best design points of a refrigeration system and calculate an adiabatic characteristic to change outdoor temperature. The best design points such as refrigerant charge and capillary length were experimentally investigated. And the calculation model is conducted as a function of calculation parameters and outdoor temperature. According to this study results, the best design points of a refrigeration system are each 95g of a refrigerant charge and 3500/3500mm of capillary lengths. And the power consumption is 13.578 Kwh/month. And a part of the worst heat loss is a front side of a domestic Kim-Chi refrigerator body.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.10
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• pp.993-1001
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• 2001

Experimental investigation on the performance of dual-evaporator refrigeration system with an ejector has been carried out. In this study, a hydrofluorocarbon (HFC) refrigerant R134a is chosen as a working fluid. The condenser and two-evaporators are made as concentric double pipes with counter-flow type heat exchangers. Experiments were performed by changing the inlet and outlet temperatures of secondary fluids entering condenser, high-pressure evaporator and low-pressure evaporator at test conditions keeping a constant compressor speed. When the external conditions (inlet temperatures of secondary fluid entering condenser and one evaporator) are fixed, results show that coefficient of performance (COP) increases as the inlet temperature of the other evaporator rises. It is also shown that the COP decreases as the mass flaw rate ratio of suction fluid to motive fluid increases. The COP of dual-evaporator refrigeration system with an ejector is superior to that of a single-evaporator vapor compression system by 3 to 6%.