• Progress in Superconductivity and Cryogenics
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• v.17 no.3
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• pp.41-46
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• 2015

Recently, the development of the HTS power cable is actively promoted. As the length of HTS power cable increases, there have been many efforts to develop large capacity cryocooler. Among the various cryocooler, the Brayton refrigerator is the most competitive for HTS power cable. The Brayton refrigerator is composed of recuperative heat exchangers, a compressor, and a cryogenic turbo expander. In these components, the cryogenic turbo expander is a part to decrease the temperature and it is the most significant component that is closely related with overall system efficiency. It rotates with high speed using a high-pressure helium or neon gas at cryogenic temperature. This paper describes the design of a 10 kW class Brayton refrigeration cycle and the cryogenic turbo expander. Flow and structural analysis are performed for the rotating impeller and nozzle to verify the efficiency and the design performance.

• Journal of Power System Engineering
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• v.12 no.4
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• pp.52-56
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• 2008

The necessity of diagnosis of the rotating machinery which is widely used in the industry is increasing. Because vibration diagnosis can avoid sudden breakdown of machine and reduce the maintenance costs. In chemical factory, Air-compressor and refrigerator which can affect the performance and capacity of output are important machine. Therefore, in this paper, the vibration of reassembled air-compressor and refrigerator after explosion is measured for checking the machine condition. The result of diagnosis and solution is discussed in this paper.

• Progress in Superconductivity and Cryogenics
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• v.10 no.1
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• pp.67-70
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• 2008

Performance of integral type Stirling refrigerator used for cooling infrared detector is affected by principal factors such as design factors and operating factors. Operating factors include charging pressure and operating frequency. The purpose of this paper is to examine the basic design analysis on the integral type Stirling refrigerator and the changes in performance through experiments on operating factors.

• Journal of the East Asian Society of Dietary Life
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• v.7 no.3
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• pp.355-363
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• 1997

This study was designed to investigate development points for automatic ice maker which met consumer's demand. Basic data about using ices in Korean's dietary life, were collected from Seoul and Kyunggi-do residences and analyzed by SPSS program. The results were as follows; 93.7% of respondents had 3 major domestic brands' refrigerator and 41.4% of them had medium-large capacity(400-519L). 65% of respondents had a refrigerator that was purchased less than five years. 15.5% of respondents had one more refrigerator. Among of them, major refrigerator was located in kitchen(67.7%) and minor was in kitchen(29.8%) and in veranda or multi-purpose room(26.3%). 66.2% of respondents always prepared ices in ice container, and 85% of them used ice only in summer. Boiling water with barley or corn was used as drinking water (45.6%) and boiled or purified tap water was used to make ice (38.6%) commonly. In cooking, ice was used especially in cold soup with cucumber and seaweed(89.9%), ice-tea or ice-coffee(81%), and fruit punch(64%). The next commonly using ice was adding in alcoholic beverage such as whiskey(57.4%), in Koreans traditional drink(Misugaru) (45.2%) and juice. The purpose of using ice was to cool in soft drink (58.6%), to cool in cooking food(19.9%), to eat ice itself(14.0%), and to enjoy more fantastic taste and mood(3.8%). In whiskey, the purpose of using ices was to control alcoholic content (52.9%). There was no significant difference between sex in the purpose of using ice, but there was significant differences between age(p＜0.05). Seasonal variations in using ice, there were significant differences according to sex, age, roles in family, amount of preparation of ice, socio-economic level and brand and capacity of refrigerator in respondent's home.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.278-280
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• 2003

We manufactured neon liquefaction system for cooling system of HTS motor. The neon liquefaction system consists of a GM refrigerator, a liquefaction vessel and a vacuum chamber. It is found that the neon starts to be liquefied in the liquefaction vessel after 35 minutes of cool-down from gas state of 294k. Capacity of neon liquefaction system and the liquefaction rate were about 36W, 0.1g/s.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.3
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• pp.141-148
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• 2015

The cryogenic cooling system should maintain the HTS power cable below 77 K. As the length of HTS power cables has increased, there have been many efforts to develop large capacity cryocoolers. Brayton, Joule-Thomson, and Claude refrigerators were considered for the large capacity cryocooler. Among the various cryocoolers, the Brayton refrigerator is the most competitive in terms of the HTS power cable. At present, it is thought that a 10-kW class refrigerator will be able to be used as a unit cooling system for the commercialization of HTS power cables in the near future. The Brayton refrigerator is composed of recuperative heat exchangers, a compressor, and a cryogenic turbo expander. Among the various components, the cryogenic turbo expander is the part that decreases the temperature, and it is the most significant component that is closely related with overall system efficiency. It rotates at high speed using high-pressure helium or neon gas at cryogenic temperatures. This paper describes the design of a 300-W class Brayton refrigeration cycle and the cryogenic turbo expander as a downscale model for the practical 10-kW class cycle. Flow and structural analyses are performed on the rotating impeller and nozzle to verify the efficiency and the design performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05b
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• pp.50-53
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• 2001

The thermoelectric refrigeration technologies have no moving parts. compressor, or piping required. In this study, the basic capacity of thermoelectric devices and development on some thermoelectric refrigerator were reviewed and basic technical concepts related with many kinds of thermoelectric materials were discussed. Especially the result of performance test on thermoelectric refrigerator whose minimum temperature of $-2^{\circ}C$ was introduced briefly.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.1
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• pp.11-19
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• 1994

An optimal design for Gifford-McMahon/Joule-Thomson(GM-JT) refrigerators was performed by a numerical method. The design goal was to meet the cooling requirement for MRI systems, which was 3 Watt at 4 K. A general cycle analysis program was written to calculate the cooling capacity of the GM-JT refrigerators for the givenstage GM refrigerator. The program was executed for a specific refrigerator with various design parameters. The optimal values for the maximum cooling were found for the sizes of the heat exchangers, the mass flow rate of helium, and the compression pressure.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.6
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• pp.871-879
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• 1998

The refrigerator consists of many components such as compressor condenser expansion valve evaporator and the cabinet which filled by urethane foam. In this paper the heat leakage of refriger-ator is measured by the new experiment method which is different from a present method, The devi-ation of the UA(overall heat transfer coefficient times area) between the simulation and experiments is about 7-8%. Using the modeling of various components of refrigeration system a performance analysos of CFC 12 and HFC 134a is performed numerically on the UA. As the results of this study according to increase the heat leakage the refrigeration load and mass flow rate of refrigerant are increased. And the increase of the mass flow rate results in the increase of the condensing and evapo-rating temperature. Therefore according to increase of the heat leakage the COP leads to increase because the increase of refrigeration capacity is larger than the increase if compressor power.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.1
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• pp.1-10
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• 1992

The purpose of this paper is to provide an efficient method of operating and designing HVAC systems for reasonable energy consumption in building. Accroding to the conditions of indoor temperature and humidity, and the methods of dividing and grouping the capacity of boiler and refrigerator, the amount of their annual energy consumptions is simulated by using an energy analysis program which is developed in this paper, and opatimal design methods of HVAC system are suggested as well.