• Title/Summary/Keyword: Liquid Nitrogen

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A study on the discharge characteristics of liquid nitrogen using at cryogenic cable (극저온 전력케이블을 액체질소에 대한 방전특성에 관한 연구)

  • 이현동;주재현;박원주;이광식;이동인
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 1996.11a
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    • pp.125-129
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    • 1996
  • This study describes that electrical breakdown of liquid nitrogen which is influenced with bubble has been investigated as liquid nitrogen is used coolant of high temperature(T/sub c/) superconductivity. In order to investigate breakdown of liquid nitrogen, we formed electrode system of parallel and vertical configuration toward gravitutional direction. In case of changing with electrode configuration of equal electrode and gap spacing in uniform and nonuniform electric field bubble behavior is changed. In result of that, breakdown voltage is changed. Therefore, this study proved that electrode configuration must be formed the smallest existing probability of bubble between two electrodes in order to increase breakdown strength of liquid nitrogen at atmosphere pressure.

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An Analysis of Heat Transfer and Pressure Drop Characteristics for Optimum Design of Cryogenic Heat Exchanger used for Liquid Nitrogen Cooling (액체질소 냉각용 극저온 열교환기의 최적설계를 위한 열전달 및 압력강하 특성 분석)

  • Ko, Ji Woon;Jeon, Doong Soon
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.30 no.1
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    • pp.24-32
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    • 2018
  • In this paper, analytical studies were conducted to obtain optimal design factors and analysis parameters of liquid nitrogen cooling exchanger applied in cryogenic refrigerator. The target value of heat transfer rate was more than 1 kW and pressure drop was less than 40 kPa. Design factors of cryogenic heat exchanger included width of channel and configuration of paths. Analytical factors of liquid nitrogen cooling exchanger included temperatures of coolant header surface and inlet liquid nitrogen. The width and number of channels in the design parameters were 0.0050~0.0150 m and 4~8, respectively. The configuration of channel path was 4 ways. Temperatures of coolant header surface and inlet liquid nitrogen in analytical parameters were 74 to 78K and 82 to 86K, respectively. As result, the design factor and analysis parameter satisfying the target values were obtained. The biggest heat transfer rate was 1.36 kW with pressure drop of 32.26 kPa.

Effects of Pressure on the Breakdown Characteristics of Cryogenic Liquid and Gaseous Nitrogen (극저온 액체 및 기체 질소의 압력에 따른 절연파괴 특성)

  • 백승명;정종만;김상헌
    • Progress in Superconductivity and Cryogenics
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    • v.4 no.2
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    • pp.1-4
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    • 2002
  • Electrical properties of liquid nitrogen ($LN_2$) and gaseous nitrogen($GN_2$) have become of great interest again since the discovery of high temperature superconductors . It is very important from a point of superconducting apparatus protection to elucidate breakdown characteristics in $LN_2$ and $GN_2$ at atmospheric and pressurized conditions Therefore. this paper studies the effect of pressure on the breakdown characteristics in $LN_2$ and $GN_2$. Af high voltage is applied to electrode system with uniform and non-unform field in various gap length. And Breakdown voltages of $LN_2$ and $GN_2$ are investigated under AC voltage for Pressure ranging from 0 and 0.5 MPa. This research presented basis information of electrical insulation design for liquid nitrogen immersed HTS power apparatus.

Characteristics of Surface Flashover on Partially Immersed of Spacer in Liquid Nitrogen (액체질소 중에서 spacer의 부분적 침적에 대한 연면 방전특성)

  • 김영석;이병성;백승명;정종만;정순용;김상현
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.2
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    • pp.177-182
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    • 2000
  • Composite insulation system of liquid nitrogen and solid spacer is widely applied in high temperature superconduction power machine. This study has three step procedure. As follow, first step is composition of parallel deposited electrode and vertically deposited electrode along the direction of immersion in liquid nitrogen(LN2). Second step is investigation into surface flashover voltage of solid spacer under partially immersed in LN2, and last step is comparison the result of this research with that of fully immersed in LN2 and at cryogenic temperature gaseous nitrogen(GN2). This result presented that surface flashover voltage along solid spacer half immersed in LN2 was almost the same as that of fully immersed spacer when the thickness of spacer(t) was t<10mm. In the case of t> 10mm, however, spacer flashover voltage was equal to that obtained in GN2 at cryogenic temperature. And the immersed direction functions as role of deciding the difference of surface flashover voltage.

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Investigation of LN2 Lubrication Effect in Cryogenic Machining -Part 3: Nitrogen Lubrication Mechanism related to Chip Microstructures- (초 냉각 가공에서의 LN2 의 감찰 효과 연구 -절삭 칩 미세 구조에 관한 나이트로젠 감찰-)

  • 전성찬;정우철
    • Proceedings of the Safety Management and Science Conference
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    • 2002.05a
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    • pp.221-225
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    • 2002
  • Machinability improvement by the use of liquid nitrogen in cryogenic machining has been reported in various studies. This has been mostly attributed to the cooling effect of liquid nitrogen. However, No study has been found in discussion on whether liquid nitrogen possesses lubrication effect in cryogenic cutting. This paper presents lubrication mechanism related to chip microstructure. The friction reduction was further reflected In larger shear angle and less secondary deformation in the chip microstructures.

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Effect of Nitrogen Injection Pressure on Lqiufied Engine Performance (질소 분사 압력이 액화질소 엔진의 성능 특성에 미치는 영향)

  • Shin, Donggil
    • Journal of Energy Engineering
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    • v.26 no.1
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    • pp.28-33
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    • 2017
  • A liquid nitrogen engine is a highly clean power engine, which does not emit any hazardous substances in its fumes. Additionally, it has an advantage over electric vehicles, as its energy density is larger than that of a battery. The use of an existing liquid nitrogen engine is typically limited to the reciprocation type. In this study, the concept of a nitrogen engine equipped with a scroll expander is introduced. The engine's efficiency was shown to increase when the scroll expander was utilized in the engine, while also adding to the simplification of the structure. Therefore, compared to the existing reciprocation-type engine, the engine with the scroll expander has the potential to be both technically and economically more competitive. In this study, the performance of a liquid nitrogen engine equipped with a scroll expander was analyzed while altering the injection pressure profile of liquid nitrogen.

Visualization of Cryogenic Nitrogen Spray from a Pintle Injector (초저온 질소 분사 핀틀 인젝터 분무의 가시화)

  • Lee, Keonwoong;Son, Min;Shin, Dongsoo;Yoon, Youngbin;Kim, Jeong Soo;Koo, Jaye
    • Journal of the Korean Society of Propulsion Engineers
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    • v.21 no.2
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    • pp.41-47
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    • 2017
  • By using liquid and gaseous nitrogen as simulants, effects of pintle opening distance and simulant supplying condition on spray from pintle injector were investigated qualitatively. The experiment was performed by fixing the liquid supply pressure and varying the opening of the pintle and the supply pressure of gaseous nitrogen. Shadowgraph method with CCD camera was used for image visualization, and the differences of liquid-gas spray were compared by image post processing. In case of liquid nitrogen single injection, as the opening distance was increased, the injection speed was decreased. Therefore, the end of liquid sheet were converged to the center of spray. In the case of liquid nitrogen/Gaseous nitrogen spray, although shadowgraph images look similar to each other, It is shown that it can be analysed by image post processing.

Cryogenic Performance Test of a Turbopump Inducer (터보펌프 인듀서에 대한 극저온 성능시험)

  • Kim, Jin-Sun;Kim, Jin-Han;Hong, Soon-Sam
    • Journal of the Korean Society of Propulsion Engineers
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    • v.11 no.1
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    • pp.64-70
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    • 2007
  • A test facility was developed where an inducer for a liquid rocket engine turbopump can be tested using liquid nitrogen as a working fluid. At the facility, a hydrodynamic performance test and a cavitation performance test for an oxidizer turbopump were carried out. Head-flow relation at liquid nitrogen test was similar to the case at water test. However, cavitation performance at the liquid nitrogen was superior to the case at water test, which results from the thermodynamic effect of cavitation.

Cryogenic Performance Test of a Turbopump Inducer (터보펌프 인듀서에 대한 극저온 성능시험)

  • Hong Soon-Sam;Kim Jin-Sun;Kim Jin-Han
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2006.05a
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    • pp.93-99
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    • 2006
  • A test facility was developed where an inducer for a liquid rocket engine turbopump can be tested using liquid nitrogen as a working fluid. At the facility, a hydrodynamic performance test and a cavitation performance test for an oxidizer turbopump were carried out. Head-flow relation at liquid nitrogen test was similar to the case at water test. However, cavitation performance at the liquid nitrogen was superior to the case at water test, which results from the thermodynamic effect of cavitation.

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The Lubrication Effect of Liquid Nitrogen in Cryogenic Machining [I]- Part 1: Cutting Force Component with Physical Evidences - (Liquid Nitrogend의 감찰효과 -물리적 현상에 의한 절삭력-)

  • Jun Seong Chan;Jeong Woo Cheol
    • Journal of the Korea Safety Management & Science
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    • v.4 no.2
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    • pp.209-221
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    • 2002
  • Machinability improvement by the use of liquid nitrogen in cryogenic machining has been reported in various studies. This has been mostly attributed to the cooling effect of liquid nitrogen. However, No study has been found in discussion on whether liquid nitrogen possesses lubrication effect in cryogenic cutting. In machining tests, cryogenic machining reduced the force component in the feed direction, indicating that the chip slides on the tool rake face with lower friction. This study also found that the effectiveness of LN2 lubrication depends on the approach how LN2 is applied regarding cutting forces related.