• 한국초전도ㆍ저온공학회논문지
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• 제1권1호
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• pp.42-47
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• 1999

Enthalpy transport in a pulse tube was investigated by two-dimensional analysis of mass. momentum an energy equations of the gas as well as energy conservation of the tube wall. The mean temperature of the gas and the tube wall was obtained directly by assuming that the outer surface of a pules tibe wall is adiabatic. Axial profile of mean temperature is small. but it deviates significantly from linear profile when the dimensionless frequency is large. Effect of operating frequency. tube wall thickness, velocity ratio and velocity phase angle between both ends of a pulse tube on net enthalpy flow were shown.

• 한국초전도ㆍ저온공학회논문지
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• 제12권4호
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• pp.1-7
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• 2010

The pulse tube cooler as an alternative of Stirling, G-M or VM cooler to overcome the requirement from the various application fields is described. The necessity of the object oriented cooler development is explained to realize the cryocooler of more energy-efficient, more reliable, more compact and less expensive than what is currently available commercially.

• 한국초전도ㆍ저온공학회논문지
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• 제5권1호
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• pp.118-122
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• 2003

Pulse tube refrigerator, which has no moving parts at its cold section, is attractive fer obtaining higher reliability, simpler construction and lower vibration than Stilting refrigerator or Gifford-McMahon refrigerator. Commonly used means to achieve optimum performance of Stilting type pulse tube refrigerator is an inertance tube. The use of inertance tube is a simple way to generate the phase shift needed to make pulse tube refrigerator operate as efficiently as Stilting refrigerator. In this study, the performance of the inertance pulse tube refrigerator (IPTR) was investigated experimentally. An in-line type IPTR consists of a linear compressor with two reciprocating pistons driven by linear motors, which makes pressure waves, a regenerator a pulse tube with the inertance tube, and a reservoir, The dynamic pressures (the compressor, pulse tube, reservior) and the temperature at the cold heat exchanger are measured to explore the dependence of the inertance tube on the performance of the IPTR. The experimental results show the dependency of cool-down characteristics, no-load temperature and amplitude of the pressures on the length and diameter of the inertance tube.

• 한국초전도ㆍ저온공학회논문지
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• 제14권1호
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• pp.34-37
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• 2012

In this paper, configurations and performance of a pulse tube engine (PTE) are investigated. The configuration of PTE is basically designed by using a concept of energy flow. The configurations of PTE are classified as a PTE with two pistons and a PTE with one piston. First, the PTE with two pistons is simulated and the Carnot efficiency is about 41 %. The phase difference of between motion of two pistons located at expander and compressor mainly effects the performance of the PTE. Second, the PTE with one piston is designed. From a concept of analogy, the piston of compressor is replaced by a compliance tube and a resonator. The PTE with one piston is identical with a thermoacousic engine and has the large volume because the compliance tube and resonator are consisted of large volume tubes. Therefore, we will consider each usefulness of the compact PTE with two pistons and the huge PTE with one piston for PTE applications and the judgement of feasibility.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.159-162
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• 2003

Cooling with easy, reliable cryocooler is highly desirable for the commercial and military application The pulse tube refrigerator has no moving parts at the cold end, so that the mechanical vibration and magnetic noise can be reduced to the low level with higher relaibility and longer lifetime than the Stilting cryocooler. The inertance tube improve the performance of pulse tube refrigerator by providing optimal phase shift between pressure and amss flow rate, and it is easiest to implement at large cooling capacity and high operating frequency. In this study, the performance of the inertance pulse tube refrigerator was investigated by analysis. The results show the influence of the diameter and length of the inertance tube on the performance of the refrigerator.

• 한국초전도ㆍ저온공학회논문지
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• 제8권3호
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• pp.63-69
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• 2006

This paper describes the effect of rotating frequency on the pulse tube of Stirling type pulse tube refrigerator. Various conditions were analyzed by two-dimensional analysis with several dominant non-dimensional parameters. With the additional pressure term influenced by centrifugal force in rotating condition, the linearized conservation equations of mass, momentum, energy of the gas were solved to obtain the first order variables and calculate the enthalpy flow in rectangular coordinates. The rotational effect in pulse tube for the refrigerator's performance were quantitatively evaluated. According to the first order analysis, the enthalpy flow decreases with the rotating speed.

• 한국초전도저온공학회지:초전도와저온공학
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• 제6권2호
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• pp.42-46
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• 2004

금속 테이프 위에 초전도층을 박막형태로 증착시켜서 제조되는 고온초전도 선재인 coated conductor (CC)는 powder-in-tube 공정으로 제조되는 1세대 고온초전도 선재에 비해 액체 질소 온도에서 높은 임계 전류 밀도와 우수한 자장 특성을 가지면서 더 경제적으로 제조 가능하기 때문에 액체질소온도에서 작동 가능한 초전도전력기기 개발에 반드시 필요한 부분으로 인식되고 있다. 최근 국내외적으로 다양한 증착 방법을 사용하여 전력기기 응용이 가능한 장선의 CC 제조공정을 개발하려는 연구가 활발히 진행되고 있다. 특히 외국의 경우 이미 CC 선재의 상업화를 위해 기업체가 중심이 되어 집중적인 연구 개발이 이루어지고 있다.(중략)

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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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).

• 한국초전도ㆍ저온공학회논문지
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• 제3권2호
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• pp.69-76
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• 2001

Unsteady components of the second-order axial velocity and temperature within a tapered pulse tube were obtained by using a novel hybrid method of solution which combines an analytical solution with a numerical solution. The effects of operating frequency, taper angle and cold eng temperature on the unsteady components of the second-order axial velocity and temperature were shown. The unsteady component of the second-order mass flux had the amplitude of the same order as the steady component when the velocities at the ends of the pulse tube have only first-order components.

• 한국전기전자재료학회논문지
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• 제14권7호
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• pp.606-610
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• 2001

Bi-2212 HTS tube was fabricated by centrifugal forming and partial melting processes. Bi-2212 bulk tube has been optimized to achieve smooth surface and uniform thickness. The slurry was prepared in the mixing ratio of 10:1 between Bi-2212 powder and binder and initially charged into the rotating mold under the speed of 300~450 rpm. Heat-treatment was performed at the temperature ranges of 860~89$0^{\circ}C$ in air for partial melting. the HTS tube fabricated by centrifugal forming process at 89$0^{\circ}C$ under the rotating speed of 450 rpm was highly densified and the plate-like grains with more than 20${\mu}{\textrm}{m}$ were well oriented along the rotating axis. The measured Tc and J$_{c}$ at 10K on specimen heat treated at 89$0^{\circ}C$ was around 85 K and 1,200 A/$\textrm{cm}^2$ respectively.y.