• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.189-192
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• 2002

In this study, The experimental open-tube-type and close-tube-type thermoacoustic refrigerator were constructed. The resonant characteristics of a thermoacoustic refrigerator were investigated. In order to determine the optimum resonant tube length and frequency, We changed the length of resonant tube from 400mm to 850mm and the frequency from 100Hz to 1000Hz. In case of first harmonic, the temperature difference of open-tube-type (1/4 wave) refrigerator was $41^{\circ}C$(resonator length :500mm). The temperature difference of close-tube-type (1/2 wave) refrigerator was $43^{\circ}C$(resonator length :850mm). In this experiments, the experimental 1/2 wave refrigerator is slightly cooler than the experimental l/4 wave refrigerator.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.71-76
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• 2002

To achieve good cryogenic circumstances by Gifford-McMahon cryocooler, we have to constitute optimal conditions with various factors for G-M cryocooler. In this study, cool-down characteristics were presented with some factors using brass matrix mesh (1st stage) and Pb ball (2nd stage) as regenerator materials for the heat exchangers. The effects of the variations of Helium gas pressure and cycle frequency on the cooling capacity of G-M cryocooler are investigated experimentally. The presented results could be summarized as follows : 1) As the steady state pressure increases, 'no load temperature' decreases but cooling capacity increases. 2) It is confirmed that the characteristics of the specific heat of the regenerator materials agree well with the cool-down characteristics of 10 K cryocooler.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.193-196
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• 2002

The thermoacoustic refrigerator has not only considerable possibility but also commercial usability, because it has high reliability, lower vibration, no moving part, and can easily be constructed. In order to determine the optimum resonant tube length and the frequency, the open-tube-type(3$\lambda$/4) and close- tube - type (2$\lambda$/2) thermoacoustic refrigerator were constructed. In third harmonic, the temperature difference of 3$\lambda$/4 refrigerator was $53^{\circ}C$(resonator length :400mm). In second harmonic, the temperature difference of 2$\lambda$/2 refrigerator was $51^{\circ}C$(resonator length :400mm).

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.181-184
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• 2002

The purpose of this study is to analysis the charging gas effect on the resonance and performance characteristics of the linear compressor for small scale FPFD Stirling refrigerator. To ensure high performance of FPFD type Stirling refrigerator, the operating frequency of the refrigerator should be around the natural frequency of compressor. The gas spring effect which is induced from pressure change in cylinder due to motion of pistons has significant effect on the natural frequency of the compressor. The numerical results show the linear compressor has high natural frequency when the charging pressure of working fluid is high.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.67-70
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• 2002

The Stirling cryocooler with helium refrigerant has been widely used for the cooling of the infrared detector, and the alternatives of the helium in the Stirling cryocooler are nitrogen and hydrogen gas. In this study, the performance experiment of the small FPFD(Free Piston and Free Piston) type Stirling cooler and the moving coil type, dual acting linear compressor was performed when the nitrogen and helium is used for the working fluid The results show that the nitrogen refrigerant has small cooling capacity compared with the helium, but the performance characteristics of the linear compressor does not greatly changed.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.63-66
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• 2002

A free piston and free displacer (FPFD) Stilting cryocooler for the cooling infrared and cryo-sensor is currently under development at Korea Institute of Machinery & Materials. In this study, the dynamic characteristics of the displacer in the expansion space of the Stirling cooler was investigated by experiment. The experimental results show that the Stirling cryocooler has maximum cooling capacity at the certain relation between operating frequency and natural frequency of the displacer and the operating frequency of the Stirling crycooler should be determined by natural frequency of the linear compressor and displacer.

• Progress in Superconductivity and Cryogenics
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• v.6 no.1
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• pp.53-58
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• 2004

A Miniature inertance pulse tube refrigerator was designed and tested with a 10 W compressor. Erperiments were carried out for different pulse tube length and inertance tube length. An adiabatic model which considered the pressure drop in the regenerator was used to analyze the performance of the pulse tube refrigerator. Among various design parameters which should be optimized, the pulse tube length and the inertance tube length were optimized. PdV work and several different loss mechanism were included in the analysis to simulate more accurately the physical phenomena in the pulse tube refrigerator. Nevertheless, the simulation program could not completely predict the porformance of the refrigerator. The possible reason for the difference of the optimal point between the simulation and the experiment was explained.

• 기계와재료
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• v.22 no.3
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• pp.120-129
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• 2010

획기적으로 선명한 영상의 구현, 휴대 용이성 및 정확한 온도분포의 구현이 가능한 초점면 배열 방식의 적외선 검출기는 탐지도 및 분해능 향상을 위해 액체질소 온도수준의 극저온냉각을 요구한다. 냉동기의 저온부에 적외선 검출기를 직접 부착하는 일체형 스터링 극저온냉동기는 효율적인 적외선 검출기의 냉각이 가능할 뿐 만 아니라, 소형/경량화가 용이하여, 기동 및 휴대용 열상장비용 극저온냉각을 위해 많이 활용되고 있다. 적외선 검출기 냉각용 즉저온냉동기는 다양한 열/진동/충격/전자파 등의 운용환경조건에서 검출기를 액체질소 온도수준으로 냉각/유지할 수 있어야 하며, 안정적인 시스템의 운용을 위한 충분한 신뢰성이 확보되어야 한다. 본 고에서는 민군 겸용기술사업을 통해 국내에서 개발된 열상장비 냉각용 일체형 스터링냉동기의 기술적 특징 및 환경/신뢰성 시험 결과를 소개하고자 한다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.6
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• pp.683-694
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• 1998

The application of hydrocarbon refrigerants in a hermetic reciprocating compressor for refrigerator is investigated. The selected refrigerants are isobutane(R600a), propane(R290), R12, binary mixture of R600a/R290, and OS-21CII. Both theoretical and experimental investigations have been performed for the selected refrigerants. The test results of hydrocarbon refrigerants have been compared to the traditional refrigerant(R12). The results show that hydrocarbon refrigerants(HC-Blend, OS-21C II) are very good alternatives in the refrigeration system for R12.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.6
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• pp.413-420
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• 2011

Thermodynamic cycles using binary mixtures as working fluids offer a high potential for utilization of low-temperature heat sources. This paper presents a thermodynamic performance analysis of Goswami cycle which was recently suggested to produce power and cooling simultaneously and combines the Rankine cycle and absorption refrigeration cycle by using ammoniawater mixture as working fluid. Effects of the system parameters such as concentration of ammonia and turbine inlet pressure on the system are parametrically investigated. Results show that refrigeration capacity or thermal efficiency has an optimum value with respect to ammonia concentration as well as to turbine inlet pressure.