• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.517-522
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• 2005

A cold storage refrigerator using phase change material(PCM) has been developed and its performance test results are provided here. The inner temperature of the refrigerator is controlled with forced convection driven by a fan using a DC battery. At the first, to freeze all the PCM of the ambient temperature by a built-in refrigerating machine, it took about 8 and 10 hours respectively at the refrigerator and the freezer mode. Then, without external power supply, the inner temperature of the cold storage refrigerator has been maintained at $-18{\pm}1^{\circ}C$ during 14 hours at the freezer mode and maintained at $3{\pm}^{\circ}C$ during 34 hours at the refrigerator mode. Just after the end of its valid usage as a refrigerator or a freezer, it took about 6 hours to refreeze the PCM for its reuse. During the test, the ambient temperature was kept at $30^{\circ}C$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.1
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• pp.133-146
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• 1999

The charge operation of an ice storage system has been analyzed in this paper. The thermal characteristics of major components of the ice storage system. i.e., the refrigerator and the ice storage tank are evaluated from performance tests on an existing ice storage system. Based on the measured data for thermal characteristics, a simulation is carried out for the charge operation and the effect of the refrigerator size on the system performance is investigated. The results indicate that the larger the refrigerator size for a given storage capacity, the lower the inlet temperature of the ice storage tank so that the lower the efficiency of charge operation. It is also found that there exists an optimal size of the refrigerator with which the ice storage at the end of the charge operation is maximized, but the complete charge is not possible even with the optimally sized refrigerator. This leads to the result that the design capacity of the storage tank should be larger than the required amount of cold energy for the daytime cooling considering the practically chargeable amount of cold energy during the nighttime. Where the cooling load sharing of the storage is 40%, the nominal capacity of an ice storage tank needs to be larger than the required storage amount by 30%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.3
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• pp.382-395
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• 1995

A numerical study has been performed on flow characteristics in a domestic refrigerator whose size is $540mm{\times}1,530mm{\times}680mm$, considering existence of a fan and evaporator. The flow field has been simulated with the low Reynolds number $k-\bar{\varepsilon}$ turbulent model and SIMPLE algorithm based on the finite volume method. The region of fan which makes driving force for cold air distribution was modeled as a region in which momentum sources are generated uniformly. The concept of the distributed pressure resistance was applied to describe the momentum loss from evaporator. The result showed that the rate of cold air distribution into freezing room and cold storage room was almost 7 : 3.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.04a
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• pp.25-28
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• 2004

This paper describes an intelligent diagnostic system for the refrigerator which is used for the cold-storage of farm produce. The propose method measures the temperature of the compressor, condenser and evaporator in the refrigerator and uses the measured values to diagnose the system. It is shown through the implementation that the developed system is efficient for the fault observation and diagnose of the refrigerator.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.3
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• pp.450-455
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• 1997

Scallop, Patinopecten yessonensis(Jay), cultivated in the cold east coast of Kwangwon region, Korea, is expected to be producted to about 50,000 tones in 2000 year. Freezing is one of the most effective methods applied for soraging seafoods. But, the domestic refrigerator with an automatic defrost system shows the temperature fluctuation during defrosting, thus might result in the deterioration of the frozen foods. In this study, the domestic refrigerator with an automatic defrost system, temperature fluctuation from -18 to -5$\pm$1$^{\circ}C$ and fluctuation intervals from 16 to 20 hr, was used for storing scallop. pH was decreased rapidly after 3 month storage, while the content of amino nitrogen was increased continuously. The TMA content of open state was increased very rapidly on 3 month storage and then increased slowly, whereas that of vinyl package increased slowly. The VBN content was increased almost constantly with no significant differences between storage methods. The TBA content was increased up to 3 month storage with the higher value in open state than vinyl package in the beginning periods of storage, and then decreased very rapidly. The number of total viable cell was increased continuously during storage with higher number in open state than vinyl package. The estimated shelf-lives of frozen scallop with open state and vinyl package stored at -18$^{\circ}C$ in the domestic refrigerator with an automatic defrost system were 3.55 and 3.78 months, respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.2
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• pp.72-78
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• 2014

In a cold chain, the refrigerator is also employed for defrosting, by using an electric heater, which consumes 15% of the power for the system operation. In this study, the condensation heat of the refrigerant was suggested as the heat source of defrosting heat, instead of that from an electric defrost heater. The heat for defrosting was stored to a phase change material (PCM, NMP : $52^{\circ}C$) in thermal storage, and was periodically supplied to the evaporator by a circulation loop of brine. As a result, a defrost time by the PCM was obtained that was less than or equal to that by the electric heater. Moreover, power consumption during defrosting was saved by up to 99% of that of the electric heater.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.3
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• pp.277-284
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• 2001

One of the problems in a refrigerator operation is the frost formation on a cold surface of the evaporator. The frost layer is formed by the sublimation of water vapor when the surface temperature is below the freezing point. This frost layer is usually porous and formed on the cold surface of the evaporator. The frost layer on the surface of a evaporator will make side effect such as thermal resistance. However, these important factors have not been used in determining the defrosting period. Therefore, the proper defrosting operation period based on the new defrosting method is very important, and make a comparison between conventional method like electric defrost and new method in compression work, evaporation pressure, evaporation temperature.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.3
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• pp.267-272
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• 2004

In this paper a new intelligent diagnostic system for a refrigerator used for a cold-storage of farm produce was propose. It is verified that the developed system is useful for the fault observation and diagnose of a refrigerator by experimental implementation. The basic idea of the proposed system in that the temperature of major pipes at fault status differs from those at normal status. In order to realize the proposed system, the temperature measuring system and diagnostic program were developed.

• Proceedings of the SAREK Conference
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• 2004.11a
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• pp.94-94
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• 2004

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.12
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• pp.891-896
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• 2010

The objective of the present study is to reveal the effects of a phase-change material on the performance of a Kimchi refrigerator. Two-percent salt water, of which melting temperature was $-1.1^{\circ}C$, was used for the phase-change material. The salt water was packed in silicon cases and inserted between Kimchi container and the copper pipe of the evaporator. The maximum and minimum temperatures of the inner wall of the Kimchi container without salt-water pack were $-0.2^{\circ}C$ and $-8.9^{\circ}C$, which were remarkably improved by using the salt-water packs, resulting $-0.5^{\circ}C$ and$ -1.9^{\circ}C$. This shows a useful application of using phase-change materials for accurate temperature controls.