• Title/Summary/Keyword: tube

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An Experimental Study for the 77K Inertance Tube Pulse Tube Cryocooler (77K Inertance tube 맥동관 극저온 냉동기에 관한 연구)

  • Park, Seong-Je;Go, Deuk-Yong;Kim, Hyo-Bong
    • 연구논문집
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    • s.29
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    • pp.17-27
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    • 1999
  • The experimental results of the 17K inertance tube pulse tube cryocooler for cooling cryosensors are presented in this paper. In prototype experiments, linear compressor is driven by linear motor, and inertance tubes are inserted between one liter reservoir and pulse tube. Design of the inertance tube pulse tube cryo-cooler is conducted by ARCOPTR program of NASA Ames Research Center. To find optimal conditions of inertance tube pulse tube cryocooler, no load temperature and refrigeration capacity according to the variations of inertance tube volume, reservoir volume and charging pressure are measured. and the cool down and load characteristics at the particular conditions are presented. As the representative results, no load temperature of the cold end is 52.7K and refrigeration capacity is 5W at 72K..

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An Experimental Study on the Characteristics for Open-Tube and Closed-Tube Thermoacoustic Effects (2)- The 2nd, 3rd Harmonic (개방관과 밀폐관의 열음향 효과에 관한 하모닉 특성 연구(2) - 2차, 3차 하모닉)

  • 송규조;박종호;이성노
    • Progress in Superconductivity and Cryogenics
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    • v.4 no.1
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    • pp.135-139
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    • 2002
  • In this study, the experimental open-tube and close-tube thermoacoustic apparatuses were built. In order to determine the optimum length of resonant tube and the optimum length of stack, the resonant characteristics of thermoacoustic apparatuses were investigated, The length of resonant tube varies from 400mm to 850mm. The experimental frequency varies from 100Hz to 1000Hz. In case of the second and third harmonics, the maximum temperature difference of open-tube thermoacoustic apparatus is 53$^{\circ}C$ (resonator length: 400mm) and the maximum temperature difference of closed-tube thermoacoustic apparatus is 51$^{\circ}C$ (resonator length: 500mm). In the open-tube thermoacoustic apparatus, the peak efficiency point is about 2%, 55%, 69% in the resonant tube and in the closed-tube thermoacoustic apparatus, the peak efficiency point is about 2%, 41%, 50% in the resonant tube.

Some Aspects of Experimental in-Tube Evaporation

  • Ha, Sam-Chul
    • Journal of Mechanical Science and Technology
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    • v.14 no.5
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    • pp.537-546
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    • 2000
  • The heat transfer characteristics of refrigerant-oil mixture for horizontal in-tube evaporator have been investigated experimentally. A smooth copper tube and a micro-fin tube with nominal 9.5 mm outer diameter and 1500 mm length were tested. For the pure refrigerant flow, the dependence of the axial heat transfer coefficient on quality was weak in the smooth tube, but in the micro-fin tube, the coefficients were 3 to 10 times greater as quality increases. Oil addition to pure refrigerant in the smooth tube altered the flow pattern dramatically at low mass fluxes, with a resultant enhancement of the wetting area by vigorous foaming. The heat transfer coefficients of the mixture for low and medium qualities were increased at low mass fluxes. In the micro-fin tube, however, the addition of oil deteriorates the local heat transfer performance for most of the quality range, except for low quality. The micro-fin tube consequently loses its advantage of high heat transfer performance for an oil fraction of 5%. Results are presented as plots of local heat transfer coefficient versus quality.

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An Experimental Study on the Energy Separation in a Low Pressure Vortex Tube for Engine (기관적용 저압용 vortex tube의 에너지 분리특성에 관한 실험적 연구)

  • 오동진;임석연;윤면근;류정인
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.5
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    • pp.235-241
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    • 2002
  • The process of energy separation in a low pressure vortex tube with air as a working medium is studied In detail. Experimental data of the temperature of the cold and hot air leaving the vortex tube are presented. The variation of the maximum wall temperature along the inner surface of the vortex tube and the temperature distribution in the vortex tube provides useful information about the location of the stagnation point of the flow field at the axis of the vortex tube. In this study Outer tube is used for the application of Diesel engine exhaust. The hot gas flow is fumed 180° and passes the outside of the vortex tube a second time heating it. From this geometric setup of a vortex tube the effects of energy separation and the prediction of the ignition of Diesel Soot is presented by experimental data.

Heat Transfer Characteristics of Oval-Tube Heat Exchanger (타원관 열교환기의 열전달 특성)

  • 윤점열;이욱용
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.12 no.3
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    • pp.292-301
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    • 2000
  • This study experimentally investigates an air-side performance of oval tube heat exchanger against round tube heat exchanger using scaled-up model experiment for home air conditioners. A plain fin and round tube heat exchanger with 21 FPI(fins per inch) was used as a reference heat exchanger, and these were applied equally to 4 oval tube heat exchangers. Oval tube samples were designed with the same perimeter as 7.5mm diameter round tube, and their aspect ratios were 1:2, 1:3, respectively. In this study, the heat transfer and pressure drop characteristics of oval tube heat exchangers against round tube heat exchanger were also compared to one another, and an optimal samples for home air conditioners was recommended. And, general performance characteristics for an optimum oval tube samples chosen in this work was compared with round tube heat exchanger.

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A Theoretical Study for the Design of a New Ballistic Range

  • Rajesh G.;Lee J.M.;Back S.C.;Kim Heuy-Dong
    • Journal of Mechanical Science and Technology
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    • v.20 no.7
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    • pp.1019-1029
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    • 2006
  • The ballistic range has long been employed in a variety of engineering fields such as high-velocity impact engineering, projectile aerodynamics, creation of new materials, etc, since it can create an extremely high-pressure state in very short time. Of many different types of ballistic ranges developed to date, two-stage light gas gun is being employed most extensively. In the present study, a theoretical work has been made to develop a new type of ballistic range which can easily simulate a flying projectile. The present ballistic range consists of high-pressure tube, piston, pump tube, shock tube and launch tube. The effect of adding a shock tube in between the pump tube and launch tube is investigated. This improvement is identified as the reduction in pressures in the high pressure tube and pump tube while maintaining the projectile velocity. Equations of motions of piston and projectile are solved using Runge-Kutta methods. Dependence of projectile velocity on various design factors such as high pressure tube pressure, piston mass, projectile mass, area ratio of pump tube to launch tube and type of driver gas in the pump tube are also analyzed. Effect of various gas combinations is also investigated. Calculations show that projectile velocities of the order 8 km/sec could be achieved with the present ballistic range.

Development and Characteristics of the x-ray transmission anode tube for the thickness measurement of film (필름 두께 측정용 투과 양극형 x-ray tube의 개발 및 특성)

  • Kim, Sung-Soo;Kim, Do-Yun
    • Journal of the Korean Vacuum Society
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    • v.17 no.3
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    • pp.240-246
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    • 2008
  • The x-ray transmission anode Ag-target tube was developed to apply for the thickness measurement of film in the thickness range of several tens$\sim$several hundreds ${\mu}m$ and its characteristics were evaluated. The energy distribution and dose of x-ray from Ag-target tube was investigated at the tube voltage near 10 kV, and discussed in comparition with that from W-target tube. The energy distribution and dose of x-rays passing through film were measured with various thickness of Ny and PP film. From these results, it was confirmed that our x-ray tube can be applied for the thickness measurement of film.

Heat Transfer Characteristics of the Non-Uniform Grooved Tube Considering Tube Expansion (확관을 고려한 불균일 내면가공관의 전열특성)

  • Lee, Sang-Mu;Park, Byung-Duck
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.24 no.7
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    • pp.553-559
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    • 2012
  • A plate-fin heat exchanger is a type of heat exchanger widely used in air conditioners, and tubes and fins are tightly assembled by the mechanical expansion process of tubes. The tube expansion process deforms the grooves inside the tube, and the groove shapes also affect the adhesion between tubes and fins. In this study, the adhesion and heat transfer performance affected by the tube expansion of the non-uniform groove shape tube with different heights are investigated by both analysis and experiments. From the analysis method, it was shown that the contact pressure of non-uniform groove tube is higher than that of the uniform groove tube, and the most appropriate high groove number of the non-uniform groove tube is designed for the maximum contact pressure. From the experimental results, the decreasing rate of the condensation heat transfer coefficient is smaller in the non-uniform groove tube with different heights, compared to the conventional uniform groove tube. Also, the air-side heat transfer coefficient of the non-uniform groove tube with different heights is higher than that of the uniform groove tubes.

Experimental investigation of friction in expansion zone of tube hydroforming with material and lubricant (튜브 액압성형 공정의 확관영역에서 소재 및 윤활에 따른 마찰 특성의 실험적 연구)

  • Lee, G.Y.;Yim, H.S.;Lee, S.M.;Yi, H.K.;Chung, G.S.;Moon, Y.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.10a
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    • pp.359-362
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    • 2008
  • In this study, friction test was proposed to obtain coefficient of friction between tube and die in expansion zone of tube hydroforming and friction coefficients were evaluated at different materials, viscosity of lubricants and internal pressures. For this study, STKM11A and SUS tubes were prepared. The tube was expanded by an internal pressure against the tool wall. The tube was expanded by an internal pressure against the tool wall. By pushing the tube through the tool, a friction force at the contact surface between the tube and the tool occurs. From the measured geometries and FE analysis, the friction coefficients between tube and die at the expansion zone in tubular hydroforming can be estimated. The effects of the various internal pressures, viscosity of lubricants, tube materials and tube thickness on friction coefficients are discussed.

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A study on the reduction of fuel consumption for fish farm during winter season (월동시 양식장의 연료 절감 대책)

  • Park, Jong-Un;Han, Kyu-Il
    • Journal of Fisheries and Marine Sciences Education
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    • v.7 no.1
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    • pp.31-43
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    • 1995
  • For the fuel saving in the fish farm, the heat transfer performances of various tubes, XL-tube, copper-tube, copper-Nikel-tube and Al-brass-tube, were compared. The XL-tube, which is most commonly used for heating water, showed the poorest heater transfer performance, while the Al-Brass tube shows the best performance. As far as average temperature difference of four tubes concerns, XL-tube is $3.34^{\circ}C$, Copper tube is $10.34^{\circ}C$, Copper-Nikel tube is $11.3^{\circ}C$, Al-Brass-tube is $12^{\circ}C$, The best heat transfer performance of Al-Brass tube results from the enhancement of heat transfer coefficient caused by fin effect and good conductivity of the material.

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