• Title/Summary/Keyword: liquid nitrogen

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Hydraulic Performance Test of a Turbopump Inducer using Liquid Nitrogen (액체질소를 이용한 터보펌프 인듀서의 수력성능시험)

  • Kim Jin-Sun;Hong Soon-Sam;Kim Jin-Han
    • The KSFM Journal of Fluid Machinery
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    • v.9 no.4 s.37
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    • pp.20-26
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    • 2006
  • A cryogenic test facility has been developed to perform inducer and pump tests using liquid nitrogen. Performance tests of a turbopump in the maximum 50ton-thrust class can be performed with cryogenic fluid in the facility which operates at a temperature around -196oC with the rotational speed up to 30,000rpm To verify the reliability of the cryogenic pump test facility, hydraulic performance tests of an inducer were accomplished, and their results were compared with the result from a water test. The results confirm the reliability of the cryogenic test facility, and it is expected to contribute for on-going development of a turbopump for liquid rocket engines.

Experimental Study of the Evaporation of Spreading Liquid Nitrogen (확산하는 액체질소의 증발에 관한 실험적 연구)

  • KIM, MYUNGBAE;CHOI, BYUNGIL;KIM, TAE-HOON;DO, KYHYUNG;HAN, YONGSHIK;CHUNG, KYUNGYUL
    • Journal of Hydrogen and New Energy
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    • v.29 no.5
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    • pp.466-472
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    • 2018
  • The investigation of cryogenic liquid pool spreading is an essential procedure to assess the hazard of cryogenic liquid usage. In this experimental study, to measure the evaporation velocity when the pool is spreading, liquid nitrogen was continuously released onto unconfined concrete ground. Almost all of the reported results are based on a non-spreading pool in which cryogenic liquid is instantaneously poured onto bounded ground for a very short period of time. A simultaneous measurement of the pool location using thermocouples and of the pool mass using a digital balance was carried out to measure the evaporation velocity and the pool radius. A greater release flow rate was found to result in a greater average evaporation velocity, and the evaporation velocity decreased with the spreading time and the pool radius.

Solubility of Nitrogen in Liquid Iron and Iron-Carbon Alloys (용융 Fe 및 Fe-C 합금에서의 질소의 용해)

  • Lee, Seong-Won;Yang, Hoon-Yung
    • Journal of Korea Foundry Society
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    • v.4 no.4
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    • pp.30-33
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    • 1984
  • Nitrogen solubility in liquid Fe and Fe-C alloys has been measured by the levitation melting method under 1 atm $N_2$ pressure. Experiments were carried out at the temperature range of $1774-2097^{\circ}K$ and carbon content of 0-5.06wt%. The nitrogen solubilities measured in pure Fe and Fe-C alloys were $log(wt%N)_{Fe}=-424/T-1.129$ and $log(wt%N)_{Fe-C}=-[424/T+1.129+(%C)/19.14{5447/T-0.612}+(%C)^2/19.14$ 2478/T-1.265].

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A Study on Measurement and Elimination Methods of Dissolved Nitrogen in Kerosene (케로신 내 용존질소 측정 및 제거 방법 연구)

  • Lee, Wongu;Kim, Seong Lyong;Ahn, Kyubok
    • Journal of the Korean Society of Propulsion Engineers
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    • v.22 no.6
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    • pp.142-148
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    • 2018
  • To improve the performance of a launch vehicle, kerosene, a launch vehicle fuel, undergoes a densification process. Liquid nitrogen injection cooling is an effective densification method which has a simple system and is inexpensive. During the cooling process, however, nitrogen may dissolve in the kerosene, possibly resulting in changes to fuel properties. Therefore, it is essential to measure and eliminate the amount of dissolved nitrogen in the kerosene. In this study, the vacuum extraction principle is introduced to measure the content of dissolved nitrogen in the kerosene. In addition, the experimental results, which used a designed/manufactured nitrogen sampling device, are described. From the results, the validity of the nitrogen sampling device and the dissolved nitrogen measurement/elimination methods was demonstrated.

Evaluation of Freezing Rate of Marine Clay by Artificial Ground Freezing Method with Liquid Nitrogen (액화질소를 이용한 인공동결공법 적용시 해성 점토지반의 동결속도 평가)

  • Choi, Hyun-Jun;Lee, Dongseop;Lee, Hyobum;Choi, Hangseok
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.38 no.4
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    • pp.555-565
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    • 2018
  • Nowadays, the artificial ground freezing (AGF) method has been used in many geotechnical engineering applications such as temporary excavation support, underpinning, and groundwater cutoff. The AGF method conducts the freezing process by employing a refrigerant circulating through a set of embedded freezing pipes to form frozen walls serving as an excavation support and cutoff wall. Two refrigerants of brine with the freezing temperature of $-20{\sim}-40^{\circ}C$ and liquid nitrogen with the freezing (evaporating) temperature of $-196^{\circ}C$ are commonly being used in geotechnical applications. This paper performed a series of field experiments to evaluate the freezing rate of marine clay in application of the AGF method. The field experiments consisted of the single freezing-pipe test and the frozen-wall formation test by circulating liquid nitrogen, which is a cryogenic refrigerant, into freezing pipes constructed at a depth of 3.2 m in the ground. The temperature of discharged liquid nitrogen was maintained through the automatic valve, and the temperature change induced by AGF method was measured at the freezing pipes and in the ground with time. According to the experimental results, the single freezing-pipe test consumed about 11.9 tons of liquid nitrogen for 3.5 days to form a cylindrical frozen body with the volume of about $2.12m^3$. In addition, the frozen-wall formation test used about 18 tons of liquid nitrogen for 4.1 days to form a frozen wall with the volume of about $7.04m^3$. The radial freezing rate decreased with increasing the radius of frozen body because the frozen area at a certain depth is proportional to the square of the radius. The radial freezing rate was formulated as a simple equation.

Performance Test of Cooling System for the KEPCO HTS Power Cable (한전 초전도전력케이블 냉각시스템 성능시험)

  • Yang, H.S.;Kim, D.L.;Sohn, S.H.;Lim, J.H.;Choi, H.O.;Lee, B.S.;Choi, Y.S.;Ryoo, H.S.;Hwang, S.D.
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2206-2210
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    • 2007
  • As a power transmission line supplying power to a densely populated city, the high temperature superconducting (HTS) cable is expected to one of the most effective cables with a compact size because of its high current density. The verification of HTS power cable system have been progressed by KEPRI. A cooling system for a 3-phase 100m HTS power cable with 22.9kV/1.25kA was installed and tested at KEPCO's Gochang power testing center in Korea. The system consists of a liquid nitrogen decompression cooling system with a cooling capacity of 3kW and a closed circulation system of subcooled liquid nitrogen. Several performance tests of the cable system with respect to the cooling such as cooling capacity, heat load and temperature stability, were performed at several temperatures. Thermal cycle test, cool-down to liquid nitrogen temperature and warm-up to room temperature, was also performed to investigate thermal cycle influences. The outline of the installed cooling system and performance test results are presented in this paper.

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Flow Boiling Heat Transfer Characteristics of Liquid Nitrogen in Plain and Wire Coil Inserted Tubes (평활관 및 와이어코일을 삽입한 열전달촉진관에서 액체질소의 흐름비등열전달 특성)

  • Hwang Jee-Sang;Yun Rin;Kim Yongchan;Chung Jin Taek
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.8 s.239
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    • pp.927-933
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    • 2005
  • Boiling heat transfer characteristics of liquid nitrogen in a stainless steel plain tube and wire coil inserted tubes were investigated. The test tubes, which had an inner diameter of 10.6 m and a length of 1.65 m, were horizontally located. Five wire coils having different pitch and thickness were inserted into the plain tube. The pitches of the wire coils were 18.4, 27.6, and 36.8 m, and the thickness was 1.5, 2.0, and 2.5 mm respectively. Tests were conducted at a saturation temperature of $-191^{\circ}$, mass fluxes from 58 to 105 kg/$m^2s$, and heat fluxes from 22.5 to 32.7 kw/$m^2$. A direct heating method was used to apply heat to the test section. The boiling heat transfer coefficients of liquid nitrogen were represented as a function of vapor quality, which showed significant drop at the dryout vapor quality. The maximum heat transfer enhancement using the wire coil inserted tubes over the plain tube was $174\%$ for 'Wire 3' having a thickness of 2.5 mm and a pitch of 18.4 mm.

Study of Multi-Walled Carbon Nanotube Synthesis Using Liquid Nitrogen and Post-Process Filtration

  • Sornsuwit, Nuttaphong;Maaithong, Worawut
    • International Journal of Precision Engineering and Manufacturing
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    • v.9 no.3
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    • pp.18-21
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    • 2008
  • The study deals with the effects of parameters in the synthesis of carbon nanotubes in liquid nitrogen to find the most appropriate conditions such as electrical voltage and time that give carbon nanotubes with large volume and less proportion of impurity, which is a non-nanotubed carbon. The experiment employed the method of arc-discharge between graphite cathode and anode which are immersed in liquid nitrogen. The electrical DC current of 60A and 70A were applied with the time period ranging from 10 seconds to 25 seconds. It was found that the electrical current of 60A and 13 seconds arc-discharge time allowed the largest volume of carbon nanotubes generation. The longer time leads to more impurities around the carbon nanotubes. By the filtration of CNTs-suspended solution using 0.2 micrometers porous paper filter and the characterization using TEM, the carbon nanotubes synthesized in the study were approximately 25 layers multi-walled nanotubes with the average diameter of 18.2 nanometers.

Numerical Analysis of Cryogenic Liquid Nitrogen Jets at Supercritical Pressures using Multi-Environment Probability Density Function approach (다점 확률분포 모델을 이용한 초임계 압력 액체질소 제트 해석)

  • Jung, Kiyoung;Kim, Namsu;Kim, Yongmo
    • Journal of ILASS-Korea
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    • v.22 no.3
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    • pp.137-145
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    • 2017
  • This paper describes numerical modeling of transcritical and supercritical fluid flows within a liquid propellant rocket engine. In the present paper, turbulence is modeled by standard $k-{\varepsilon}$ model. A conserved scalar approach in conjunction with multi-environment probability density function model is used to account for the turbulent mixing of real-fluids in the transcritical and supercritical region. The two real-fluid equations of state and dense-fluid correction schemes for mixtures are used to construct thermodynamic data library based on the conserved scalar. In this study, calculations are made on two cryogenic nitrogen jets under different chamber pressures. Sensitivity analysis for two different real-fluid equations of sate is particularly emphasized. Based on numerical results, precise structures of cryogenic nitrogen jets are discussed in detail. Numerical results show that the current real-fluid model can predict the essential features of the cryogenic liquid nitrogen jets.

Development and performance test of a liquid nitrogen circulation pump for HTS power cable

  • Seok, Jihoon;Kim, Dongmin;Lee, Changhyeong;Kim, Manryeol;Choi, Jeongdong;Kim, Seokho
    • Progress in Superconductivity and Cryogenics
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    • v.20 no.3
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    • pp.28-33
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    • 2018
  • With the continuous performance improvement and commercialization of HTS wires, there have been many efforts to commercialize HTS power cables recently. Unlike conventional power cables, a cryogenic cooling system is required for a HTS power cable and a cryogenic pump is one of the essential components to circulate subcooled liquid nitrogen and cool the HTS power cable. Especially, the development of a reliable and high-efficiency cryogenic pump is an important issue for the commercialization of HTS power cables of several kilometers or more. In this study, we designed and fabricated a cryogenic pump for subcooled liquid nitrogen with a mass flow rate of 1.2 kg/s, a differential pressure of 5 bar, and evaluated the hydraulic performance of the pump. Impeller design was conducted to meet the target design performance with 1 D analysis model and CFD analysis. The pump performance parameters such as pressure heads, mass flow rates, and efficiencies in accordance with rotating speeds were assessed using a laboratory's performance evaluation system.