• Title, Summary, Keyword: Melting temperature

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An Experimental Study on Melting Process of Ice in a Rectangular Cavity with Different Wall Temperature (양벽온이 다른 장방형용기 내에서 얼음의 융해과정에 관한 실험적 연구)

  • Lim, W.T.;Kim, B.C.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.7 no.4
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    • pp.547-555
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    • 1995
  • Melting process of ice in a rectangular cavity with different temperature walls has been studied experimentally. Front shape of ice and melting rate were affected by initial temperature of ice and variation of temperature distribution and density gradient. When the hot wall temperature was below $8^{\circ}C$, the melting rates were higher at the bottom than those of at the top due to the density inversion, but with increasing the hot wall temperature the melting rates at the top were affected by hot wall and were higher than those of at the bottom. When the initial temperature of ice was low, melting rates were low, but with increasing the time melting rates were almost the same with those of each initial temperature of ice.

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Heat Transfer in Heat Storage System with P.C.M. - Inward Melting in a Vertical Tube (상변화 물질을 사용한 축열조에서의 열전달 - 수직원관에서의 내향용융 실험 -)

  • Shon, H.S.;Hwang, T.I.;Lee, C.M.;Choi, G.G.;Yim, C.S.
    • Solar Energy
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    • v.9 no.1
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    • pp.53-61
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    • 1989
  • In the present investigation, experiments on the melting of a phase change material were performed to research heat transfer phenomena generated by means of conduction and natural convection in the vertical tube at inward melting. The phase change material used in the experiments is 99 percent pure n-Docosane paraffin which is measured melting temperature of $42.5^{\circ}C$, latent heat of 37.5 cal/g, heat conductivity of $0.1505W/m^{\circ}C$. Experiments were performed both in the no-subcooling which is initiating it at melting temperature of phase change material, and in the subcooling which means to initiate it under melting temperature of phase change material, in order to compare and investigate the horizontal temperature history, vertical temperature history, ratio of melting and melted mass, figure of the melting front in the vertical tube. In the experimental results, heat transfer from tube wall to phase change material were due to conduction at early stage and due to natural convection with the passage of time, and then occurred melting downward from surface by volumetric expansion. Natural convection affects temperature distribution in the tube, ratio of melting and melted mass, figure of the melting front and then progress rapidly in case of nosubcooling compared to subcooling.

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A Study of Heat Storage System with Phase Change Material - Inward Melting in a Horizontal Cylinder (상변화 물질을 이용한 잠열축열조에 관한 기초 연구 - 수평원관내의 내향용융 열전달 실험 -)

  • Cho, N.C.;Kim, J.G.;Lee, C.M.;Yim, C.S.
    • Solar Energy
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    • v.9 no.3
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    • pp.44-54
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    • 1989
  • Heat transfer phenomena during inward melting process of the phase change material were studied experimentally. N-docosane paraffin [$C_{22}H_{46}$] is used for phase change material and its melting temperature is $42.5^{\circ}C$. Experiments were performed for melting of an initially no-sub cooled or subcooled solid in a horizontal cylinder, in order to compare and investigate the radial temperature distribution, ratio of melting and melted mass, various energy components stored from the cylinder wall, figure of the melting front in the horizontal cylinder. The solid-liquid interface motion during phase change was recorded photographically. The experimental results reaffirmed the dominant role played by the conduction at early stage, by the natural convection at longer time during inward melting in the horizontal cylinder. Ratio of melting and melted mass are more influenced by wall temperature, rather than by the initial temperature of solid. The latent energy is the largest contributor to the total stored energy.

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Study on the melting characteristics of the Fe-C eutectic temperature fixed-point (Fe-C 공정 온도 고정점의 용융 특성에 대한 연구)

  • Kim, Yong-Gyoo;Yang, In-Seok;Gam, Kee-Sool
    • Journal of Sensor Science and Technology
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    • v.15 no.4
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    • pp.257-262
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    • 2006
  • A Fe-C eutectic cell for thermocouple calibration was manufactured and tested to investigate its phase transition characteristics in the thermocouple thermometry. It was observed that the freezing plateaus were strongly affected by the freeze-inducing temperature $T_{f}$. In case of the melting process, the melting plateau was influenced by the previous thermal history. As $T_{f}$. in the previous freezing was lower, the melting plateau became lower with a temperature dependence as small as $-0.0015^{\circ}C/^{\circ}C$. Therefore, it was found that the freeze-inducing temperature should be fixed to obtain a reproducible phase transition temperature in the melting. After fixing $T_{f}$, the melting process was examined and it was found that long and flat melting plateau was obtained within a reproducibility of about ${\pm}0.01^{\circ}C$. Based on the observed results, it was recommended that Fe-C eutectic temperature be best realized for the melting process with a melt-inducing temperature of $+3^{\circ}C$ above the expected liquidus temperature after freezing at $-5^{\circ}C$ below the solidus temperature.

The effects of heat treatment condition on critical characteristics of HTSC bulk (열처리조건이 초전도벌크의 임계특성에 미치는 영향)

  • 임성훈;한태희;박경국;조동언;이중근;한병성
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.356-359
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    • 1997
  • The Effects of different melting temperature and holding time in the melting temperature on J$\sub$c/ of YBa$_2$Cu$_3$O$\sub$x/ based superconducting bulk using MPMG process were investigated. the value of critical current density was the largest at l120$^{\circ}C$, the melting temperature which is appointed to the mid point of (Y$_2$BaCuO$\sub$5/ + Liquid)region. With the melting temperature in which the value of J$\sub$c/ is the largest, J$\sub$c/ was again measured to see whether the holding time at this proper melting temperature has the effect on the critical characteristics. From the result above it was concluded that the melting temperature and holding time were important to improve the J$\sub$c/ and the formation of the Y$_2$BaCuO$\sub$5/. In this paper, the melting temperature obtained was l120$^{\circ}C$ and propel holding time could be obtained as 20 minute and the more holding time was not effective in the J$\sub$c/ improvement as well as the formation of Y$_2$BaCuO$\sub$5/.

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Phase transition features of binary Co-C eutectic temperature fixed-point (이원계 Co-C 공정계 온도 고정점의 특성)

  • Kim, Yong-Gyoo;Yang, In-Seok;Gam, Kee-Sool
    • Journal of Sensor Science and Technology
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    • v.14 no.6
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    • pp.381-386
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    • 2005
  • A Co-C eutectic cell for thermocouple calibration was manufactured and tested to investigate its phase transition characteristics using Type B thermocouples. It was observed that the freezing plateaus were flatter than those of melting, but the melting points were closer to the true transition temperature than the freezing points. The expanded uncertainty of melting temperature was calculated not to exceed $0.2^{\circ}C$ (k = 2). Based on the observed results, the melting process is recommended for the calibration of thermocouples.

The finite difference analysis on temperature distribution by coordinate transformation during melting process of phase-change Material (상변화 물질의 용융과정에 있어서 좌표변환을 이용한 온도분포의 해석적 연구)

  • Kim, J.K.;Yim, J.S.
    • Solar Energy
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    • v.5 no.2
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    • pp.77-83
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    • 1985
  • An analysis is performed to investigate the influence of the buoyancy force and the thickness variation of melting layer in the containment that is filled with phase-change Material surrounding a cylindrical heating tube during melting process. The phase-change material is assumed to be initially solid at its phase-change temperature and the remaining solid at any given time is still at the phase-change temperature and neglecting the effect of heat transfer occuring within the solid. At the start of melting process, the thickness of melting layer is assumed to be a stefan-problem and after the starting process, the change of temperature and velocity is calculated using a two dimensional finite difference method. The governing equations for velocity and temperature are solved by a finite difference method which used SIMPLE (Semi Implicit Method Pressure linked Equations) algorithm. Results are presented for a wide range of Granshof number and in accordance with the time increment and it is founded that two dimensional fluid flow occurred by natural convection decreases the velocity of melting process at the bottom of container. The larger the radius of heating tube, the higher heat transfer is occurred in the melting layer.

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Preparation of Thermal Bonding Fabric by using-low-melting-point Bicomponent Filament Yarn - Head tie - (저융점 복합사를 이용한 열융착 직물의 제조(I) - 헤드타이를 중심으로 -)

  • Ji, Myeong-Kyo;Lee, Shin-Hee
    • Fashion & Textile Research Journal
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    • v.11 no.3
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    • pp.474-480
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    • 2009
  • The purpose of this study is to prepare the hardness of polyester(PET) fabric by thermal bonding with low melting component of bicomponent fiber and to describe the change of physical properties of thermal bonded PET fabrics. The PET fabrics were prepared with regular PET fiber as warp and bicomponent fiber as weft. The bicomponent fiber of sheath-core type were composed with a regular PET core and low melting PET sheath. The thermal bonding of PET fabric was carried out in pin tenter from 120 to $195^{\circ}C$ temperature range for 60 seconds. In this study, we investigated the physical properties and melting behavior of PET fiber and the effect of the temperature of the pin tenter on the thermal bonding, mechanical properties. Melting peak of warp showed the thermal behavior of general PET fiber. However, melting peak of weft fiber(bicomponent fiber) showed the double melting peak. The thermal bonding of the PET fabric formed at about temperature of lower melting peak. The optimum thermal bonding conditions for PET fabrics was applied at $190{\sim}195^{\circ}C$ for 60seconds by pin tenter. On the other hand, the tensile strength of the PET fabric decreased with an increasing temperature of thermal bonding.

Molecular Dynamics Study on Atomistic Details of the Melting of Solid Argon

  • Han, Joo-Hwan
    • Journal of the Korean Ceramic Society
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    • v.44 no.8
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    • pp.412-418
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    • 2007
  • The atomic scale details of the melting of solid argon were monitored with the aid of molecular dynamics simulations. The potential energy distribution is substantially disturbed by an increase in the interatomic distance and the random of set distance from the lattice points, with increasing temperature. The potential energy barriers between the lattice points decrease in magnitude with the temperature. Eventually, at the melting point, these barriers can be overcome by atoms that are excited with the entropy gain acquired when the atoms obtain rotational freedom in their atomic motion, and the rotational freedom leads to the collapse of the crystal structure. Furthermore, it was found that the surface of crystals plays an important role in the melting process: the surface eliminates the barrier for the nucleation of the liquid phase and facilitates the melting process. Moreover, the atomic structure of the surface varies with increasing temperature, first via surface roughening and then, before the bulk melts, via surface melting.

A Study on Fusion Welding Strength of PE pipe (PE배관의 융착 강도에 관한 연구)

  • Jun, Hung-Won;Kim, Yong-Soo;Tae, Soon-Ho
    • Journal of the Korean Society of Safety
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    • v.17 no.2
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    • pp.16-21
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    • 2002
  • At present the Polyethylene piping, on supporting LNG is widely used because of it's disposition which are anti-corrosion flexible and so on. However, it has a few kinds of risk which are the possibility of piping leak, the character of easily corroded and so on. For giving solution, this study is intended to experiment the intension of the PE pipe after melted and when it is melting, the condition which are temperature and pressure is changed. the melting condition in temperature and pressure is adapted identically. After melting, it's joint is tested as intension. The result is that the effect of temperature in intension is more effective than pressure. In $210^{\circ}C$, $20kg/cm^{2}$ condition, the melting intension has the highest. Compare to the Butt melting joint and the Saddle melting joint, the former was $214kg/cm^{2}$ and the latter was $50kg/cm^{2}(bead\;2{\sim}3mm)$ and $73kg/cm^{2}(bead\;5{\sim}7mm)$. It means that the Butt melting method has more intensive than saddle. Consequently, the result shows that the liability and safety when pipe melting method is used will improve in pipe installation.