• Title/Summary/Keyword: Liquid Nitrogen

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Effects of Temperature and Pressure on the Breakdown Characteristics of Liquid Nitrogen

  • Baek, Seung-Myeong;Joung, Jong-Man;Kim, Sang-Hyun
    • KIEE International Transactions on Electrophysics and Applications
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    • v.3C no.5
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    • pp.171-176
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    • 2003
  • For practical electrical insulation design of high temperature superconducting (HTS) power apparatuses, knowledge of the dielectric behavior of both liquid nitrogen (L$N_2$) and subcooled liquid nitrogen (SL$N_2$) are essential. To achieve SL$N_2$ at atmospheric pressure, cryostat was designed and constructed. By pumping up the L$N_2$ in the outer dewar, the temperature of L$N_2$ in the inner dewar at atmospheric pressure can be controlled. The breakdown characteristics of L$N_2$ in quasi-uniform and non-uniform electrical fields for temperatures ranging from 77 K to 65 K at atmospheric pressure and pressure ranging from 0.1 to 0.5 MPa were investigated experimentally. The experimental data suggested that the breakdown voltage (BDV) of L$N_2$ is both highly temperature and pressure dependent. We also carried out statistical analysis of the experimental results using the Weibull distribution. The Weibull shape parameter m for the sphere-to-plane electrodes in SL$N_2$ was estimated to be 11 to 18.

Preservation of Fungi in Liquid Nitrogen Using Polypropylene Straws (폴리프로필렌 스트로를 이용한 곰팡이의 액체질소 보존)

  • Jeon, Young-Ah;Shin, Myung-Sook;Kim, Hyo-Jin;Kim, Dae-Ho;Go, Seung-Joo;Hong, Seung-Beom
    • The Korean Journal of Mycology
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    • v.34 no.1
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    • pp.54-58
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    • 2006
  • Liquid nitrogen storage is the most effective way to preserve many fungi including what cannot be lyophilized. The use of polypropylene straws instead of cryotubes has many advantages in economy, safety, convenience, and space-saving. We, Korean Agricultural Culture Collection (KACC), established the fungal preservation methods in liquid nitrogen using polypropylene drinking straws and introduced the methods in detail.

Temperature Characteristic of Rotor of HTS Synchronous Machine cooled by Solid Nitrogen (고체질소 냉각 고온초전토 동기기용 회전자의 온도특성)

  • Jo, Young-Sik;Hong, Jung-Pyo;Lee, Ju;Sim, Ki-Deck;Sohn, Myoung-Hwan;Kwon, Young-Kil;Ryu, Kang-Sik
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2001.02a
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    • pp.95-97
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    • 2001
  • This paper deals with cryogen, which is used solid nitrogen to keep the operating temperature of High Temperature Superconducting (HTS) synchronous machine. To make the solid nitrogen of liquid nitrogen, liquid helium (LHe) passes into and cools the heat exchanger to its own temperature. Two types of heat exchangers are designed and manufactured to make the solid nitrogen, and temperature characteristics of those compare with each other. The rotor cooled by latent heat of solid nitrogen and it is kept under 40K during 2 hours and 30 minutes without LHe.

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Estimation of Nitrate Nitrogen Concentration in Liquid Fertilizer Contaminated Areas using Hyperspectral Images (초분광 영상을 이용한 액비 오염지역의 질산성질소 농도 추정)

  • Lim, Eun Sung;Kim, I Seul;Han, Soo Jeong;Lim, Tai Yang;Song, Wonkyong
    • Journal of the Society of Disaster Information
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    • v.16 no.3
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    • pp.542-549
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    • 2020
  • Purpose: As nitrate nitrogen produced during fermentation of liquid fertilizer is a pollution indicator of water, in this study, four research areas where liquid fertilizer was sprayed were selected, and a model was designed to estimate the concentration of nitrate nitrogen pollution. Method: Prior to shooting on site, a spectrum library was constructed by dividing the ratio of liquid fertilizer into 5 groups: 0%, 25%, 50%, 75%, and 100%. PLSR (Partial least squares regression) method was applied to hyperspectral images acquired in the study area based on the aspect of spectrum. Result: The behavior of nitrate nitrogen was confirmed by 1st and 2nd differentiation of the spectrum of the constructed liquid fertilizer. PLSR concentration estimation modeling was implemented using images from field experiments and compared with actual concentration of nitrate nitrogen. Conclusion: When comparing the PLSR concentration estimation model with the actual concentration of nitrate nitrogen, it was measured that the detection is possible in high concentration areas where the concentration of nitrate nitrogen is 70mg/kg or more.

A Study of Liquid Nitrogen Inert Gas System for LNGC Diesel Engine Crank Chamber (LNGC 디젤기관 크랭크 챔버용 액체질소 불활성가스 시스템에 관한 연구)

  • Choi, Bu-Hong;Kim, Hyun-Soo
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.18 no.3
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    • pp.279-285
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    • 2012
  • It is necessary to install the inert gas system(IGS) for preventing fire and explosion in LNGC main diesel engine crankcase besides oil mist detector(OMD) unit with $CO_2$ gas injector. Therefore, to design the liquid nitrogen IGS, analytical work is conducted for predicting the heat input load of liquid nitrogen heater with two-phase stratified flow model. This paper also presents the effects of changes in pipe diameter, saturated pressure, and inclination angle by ship's movement on cryogenic two-phase stratified flows. It is found that the stratified model gives reasonable predictions, and the model is effective to predict the heat input load of liquid nitrogen IGS.

Investigation on the Self-Pressurization in Cryogenic Liquid Storage System (극저온 유체 저장 시스템의 압력 증가에 대한 연구)

  • Seo, Man-Su;Kim, Young-Kwon;In, Se-Hwan;Jeong, Sang-Kwon
    • Proceedings of the SAREK Conference
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    • 2008.06a
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    • pp.142-147
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    • 2008
  • This paper reports an analysis of self-pressurization in a closed cryogenic liquid storage system and its comparison with experimental data using liquid nitrogen. Partial equilibrium model(PEM), revised thermodynamic analysis of homogeneous model, has been applied for the pressurization in a closed tank. The vapor and liquid bulk temperature and the liquid-vapor interface temperature are separately calculated as their own representative values in this analysis. The analysis results of the partial equilibrium model are compared with the experimental data and other preceding homogeneous temperature models for validation.

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Development of Nitrogen Supply System for Launch Complex of KSLV-I (KSLV-I 발사대 질소 공급 시스템 개발)

  • Cho, Kie-Joo;Ahn, Kyu-Bok;Kim, Mun-Ki;Kang, Sun-Il;Ra, Seung-Ho;Oh, Seung-Hyub
    • Journal of the Korean Society of Propulsion Engineers
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    • v.15 no.2
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    • pp.68-73
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    • 2011
  • For the launch preparation of KSLV-I, gaseous nitrogen with various level of pressure and cryogenic liquid nitrogen are required. Nitrogen Supply System on launch complex has been developed to perform the production of high pressure gaseous nitrogen, the production of gaseous nitrogen with temperature of 273 ${\pm}$ 2K for protection purge of launch vehicle after loading of propellant and the supply of cryogenic liquid nitrogen for cooling of fuel (kerosene) and oxidizer (liquid oxygen). The operational instability of vaporizer mainly caused by its heat transfer characteristics which sensitively depends on the atmospheric conditions was removed by introducing parallel installation of two vaporizer and their switching operation. The developed Nitrogen Supply System carried out its function successfully in preparation of KSLV-I flight tests.

Development of Nitrogen Supply System for Launch Complex of KSLV-I (KSLV-I 발사대 질소공급시스템 개발)

  • Cho, Kie-Joo;Ahn, Kyu-Bok;Kim, Mun-Ki;Kang, Sun-Il;Ra, Seung-Ho;Oh, Seung-Hyub
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.11a
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    • pp.752-757
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    • 2010
  • For the launch preparation of KSLV-I, gaseous nitrogen with various level of pressure and cryogenic liquid nitrogen are required. Nitrogen Supply System on launch complex has been developed to perform the production of high pressure gaseous nitrogen, the production of gaseous nitrogen with temperature of $273{\pm}2K$ for protection purge of launch vehicle after loading of propellant and the supply of cryogenic liquid nitrogen for cooling of fuel (kerosene) and oxidizer (liquid oxygen). The operational instability of vaporizer mainly caused by its heat transfer characteristics which sensitively depends on the atmospheric conditions was removed by introducing parallel installation of two vaporizer and their switching operation. The developed Nitrogen Supply System carried out its function successfully in preparation of KSLV-I flight tests.

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A Study on Film Cooling Characteristics of Liner in Liquid Rocket Engine (액체로켓엔진에서의 상온 기체를 이용한 라이너 막냉각 특성 연구)

  • Jeon, Jun-Su;Lee, Yang-Suk;Lee, Dong-Hyeong;Kim, Yoo;Ko, Young-Sung;Chung, Hae-Seung
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2007.11a
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    • pp.170-173
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    • 2007
  • Cooling characteristics of a liner were investigated by a film cooling method using a gas nitrogen in a rocket engine. High temperature gas of this test was made by mixing liquid nitrogen with combustion gas of a liquid rocket. A supply system of gas nitrogen was additionally constructed to the existing test facility of liquid rocket engine, and a new test section consisted of a liner and a gas injection ring was manufactured. A 10 second firing test for finding cooling characteristics of the liner was successfully conducted and liner surface temperatures and hot gas temperature was obtained.

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헬륨가스 분사에 의한 액체질소 냉각에 관한 연구

  • Chung, Yong-Gap;Cho, Nam-Gyeong;Kil, Kyeong-Seop;Song, Yi-Hwa;Kim, Yu;Cho, Gwang-Rae
    • Aerospace Engineering and Technology
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    • v.3 no.1
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    • pp.205-212
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    • 2004
  • In this paper, to satisfy the temperature requirement of turbopump-inlet condition, the cooling of cryogenic propellant is performed at the simulated suction-line of the Launch Vehicle. The cooling method is by using gas helium injection. This paper investigates the effect of helium injection on liquid nitrogen, which simulates the liquid oxygen. By using helium injection, subcooling of liquid nitrogen can be achieved and in the condition of v/vL≒0.8min-¹ approximately in four minutes subcooling temperature can be achieved.

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