• Proceedings of the SAREK Conference
• /
• 2009.06a
• /
• pp.990-995
• /
• 2009

Experimental basic study was performed to understand the characteristics of sub-cooled refrigerant using a cold heat storage system. This system was made up general vapor-compression refrigeration cycle added sub-cooler and ice storage tank. The purpose of this study are to application use of cold-heat storage systems multiplicity of fields and to understand of sub-cooling system. At the condition using ice storage system, the ice making process was operated during night time by electric power. And then, the refrigerant was sub-cooled using stored cold-heat after being discharged from the air cooling condenser during the day time. Comparing the result at general operation with the operation using sub-cooling system. This study showed the effects of the sub-cooled degree. The cooling performance was increased owing to the sub-cooling of refrigerant during day time, and the compressor consume power was a little decreased. Thus the COP was also increased owing to the sub-cooling of refrigerant.

• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.1111-1116
• /
• 2008

The purpose of this study is to maintain high efficiency and reasonable use of cold-heat storage systems operated the showcase. An experimental study is carried out to manufacture the showcase system in a laboratory. Comparing the result at general operation condition with that at the new condition using ice storage system, this study showed the effects of the refrigerant sub-cooling, and with using inverter. At the condition using ice storage system, the ice making process was operated during midnight being not needed the cooling of the showcase through the continuous running of the condenser unit. And then, the refrigerant was sub-cooled using stored cold-heat after being discharged from the air cooling condenser during the day time. The cooling performance was increased owing to the sub-cooling of refrigerant during day time, hence the running time of the compressor was effectively decreased. In other words, this study showed that power consumption during daytime can be transferred to the midnight for making use of the refrigerant sub-cooling.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.5
• /
• pp.70-76
• /
• 2003

An experimental study was performed to understand the heat transfer and fluid dynamic characteristics of Sub-Cooled Hybrid Condenser (SCHC), which conventional condenser and receiver dryer are integrated into. SCHC also employs a sub-cooled refrigerant passages at the end of the condenser in order to supply perfect liquid refrigerant to the expansion unit. Throughout the present study, it was found that the developed SCHC increases in the degree of sub-cooling by 10~100% compared to conventional condenser. The excessive sub-cooling has improved the cooling performance by 10%, and that leads reduction in evaporator outlet air temperature by $1.5^{\circ}C$. Also found through the study is that the refrigerant pressure drop across SCHC is fairly increased due to insertion of the desiccant cartridge in the receiver tank which is composed of zeolite, filter and supporter plate.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.1
• /
• pp.1-9
• /
• 2004

The general method which changes sub-cooling of refrigerant is to control the expansion valve in the state of mixing with liquid and gas phase. In this study, the performance of vehicle air conditioning system is to control either changing the expansion valve or adding the sub condenser. Therefore, this research finally is tested in case of the fourth test procedure, the second test was suitable for a valve opening area due to adjusting valve slope in comparison with the other test. The other test except for the second test happened to do liquid back due to the excessively liquified refrigerant into the system. In conclusion, the second test was appeared not to be influenced upon liquid back, and it is to expect positive performance by controlling an expansion valve. Therefore, it will be also useful to research for an increase of compressor efficiency Performance improvement of an air conditioner is to reinforce the suction performance of the evaporator and increase the sub-cooling, which make use of the sub-cooling system.

• Journal of the Korean Institute of Gas
• /
• v.24 no.6
• /
• pp.77-82
• /
• 2020

In this paper, we developed a cooling system for the refrigeration truck using natural carbon dioxide refrigerant which is attracting attention as an environmentally-friendly refrigerant. We developed a high efficient environmentally-friendly refrigerated truck that converted the existing diesel vehicle into an LNG vehicle to improve emissions of truck and improved the efficiency of the cooling system by utilizing a heat of LNG vaporization. The COP of refrigerated truck system was increased 144%.

• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.1261-1266
• /
• 2008

Experimental study was performed to understand the operations of a showcase working in a discount store. Temperatures of evaporation, condenser were measured and also electric power consumption of compressor were measured. The purpose of this study is to application use of cold-heat storage systems operated the showcase. At the condition using ice storage system, the ice making process was operated during midnight being not needed the cooling of the showcase through the continuous running of the condenser unit. And then, the refrigerant was sub-cooled using stored cold-heat after being discharged from the air cooling condenser during the day time. The cooling performance was increased owing to the sub-cooling of refrigerant during day time, hence the running time of the compressor was effectively decreased. In other words, this study showed that power consumption during daytime can be transferred to the midnight for making use of the refrigerant sub-cooling. So the operating characteristics of the showcase system under various working conditions were analyzed and discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.22 no.12
• /
• pp.1184-1190
• /
• 2012

This study is focused on the experimental analysis of the noise induced by phase change of refrigerant at the entrance of capillary tube. The refrigerant is usually two-phase condition when it flowed into the capillary tube. At the entrance of capillary tube, the phase condition of refrigerant is formed by sub-cool control. If it has sufficient sub-cool temperature, all of the vapor refrigerants turned to liquid, which means there is only liquid. Otherwise, the gas is coexisted. Based on this theory, we experiment on each case by changing sub-cool temperature using refrigerant-supplying equipment. The noise level is measured for each case and compared.

• Journal of Energy Engineering
• /
• v.10 no.4
• /
• pp.357-362
• /
• 2001

A bench type ammonia-water absorber heat exchange cycle was tested by varying the system charging concentration, refrigerating valve opening and weak solution flow rate. It was observed that the cooling capacity was increased as the system charging concentration was increased. Optimum system charging concentration was found for the coolong capacity of the system. The opening rate of refrigerant expansion valve had a direct influence on the refrigerant sub-cooling at the condenser outlet. Optimum sub-cooling was found to be 0~4$^{\circ}C$. As the weak solution flow rate increased the concentration of strong solution and the evaporating pressure decreased. There existed a optimum weak solution flow rate which maximized the cooling capacity and COP.

• Journal of the Korean Solar Energy Society
• /
• v.28 no.1
• /
• pp.65-74
• /
• 2008

In this study, dynamic characteristics analysis of AC system is investigated using a cool thermal storage system. A analysing program for cool thermal storage AC system is developed. The performances are studied by several variables and dynamic characteristics. Comparing the result at conventional operation condition with that at the condition using ice storage system, this study showed the effects of the sub cooled degree, superheated degree, efficiency of compressor and evaporating temperature. At the condition using thermal storage system, the thermal storage process was operated during midnight being not needed the cooling of the AC unit through the continuous running of the condenser. The refrigerant was sub-cooled using stored energy after being discharged from the air source condenser during the daytime. The COP was increased owing to the sub-cooling of refrigerant during daytime, thus the power consumption was effectively decreased.

• Journal of the Semiconductor & Display Technology
• /
• v.21 no.2
• /
• pp.144-149
• /
• 2022

A cryogenic Mixed Refrigerant Joule-Thomson refrigeration cycle was designed to be applied to the semiconductor etching process with non-flammable constituents. 3-stage cascade refrigerator, single mixed refrigerant Joule-Thomson refrigerator, and 2-stage cascade type mixed refrigerant Joule-Thomson refrigerator are analyzed to figure out the coefficient of performance. Non-flammable mixture of argon(Ar), tetrafluoromethane(R14), trifluoromethane (R23) and octafluoropropane(R218) were utilized to analyze the refrigeration cycle efficiency. The designed refrigeration cycle was adapted to cool down the coolant of HFE7200(Ethoxy-nonafluorobutane, C₄F₉OC₂H₅) with certain constraints. Maximum coefficient of performance of the refrigeration system is obtained as 0.289 for the cooling temperature lower than -100℃. The detailed result of the coefficient of performance according to the mixture composition is discussed in this study.