• 태양에너지
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• 제9권3호
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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.

• 설비공학논문집
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• 제12권1호
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• pp.67-74
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• 2000

One of the important application of a contact melting process is a latent thermal energy storage owing to its high heat flux. In some previous works, the split fins have been employed in order to enhance the melting speed. In the present work, the close contact melting was experimentally investigated using an ice as specimen for both split and non-split fins. It was shown that the contact melting by split fins increases the melting rate compared to that of non-split ones.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2005년도 추계 학술대회 논문집
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• pp.32-37
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• 2005

The characteristics of the metal melting and radionuclide distribution of the radioactive has been investigated in a lab-scale arc furnace. The slag former based on the constituents of silica, calcium oxide, aluminum oxide, borate and calcium fluoride additions was used for melting of the stainless and carbon steel. In the melting of the stainless steel, the amount of slag formation increased with an increase of the concentration of the slag former. But the effects of the slag basicity on the amount of stag formation showed a local maximum value of the slag formation with an increase of the basicity index in the melting of the stainless steel as well as in the melting of the carbon steel. With an increase of the amount of slag former addition, the trends of the cobalt distribution into the ingot and the stag depended on the kind of slag former used in the melting of the stainless steel while the effect of the slag basicity on the distribution of the cobalt was not clarified in the melting of carbon steel. Tn the melting of the carbon steel, the strontium was captured at up to $50\%$ into the slag phase. Cesium was completely eliminated from the melt of the stainless steel as well as the carbon steel and distributed to the dust phase.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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• pp.151-155
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• 2006

The large amount of energy is consumed in a process for keeping the high temperature melting pool. For this reason, in addition to the wastes input to keep the high temperature melting pool, it is necessary for an auxiliary fuel and LOx to throw into the melting pool. So in this study, using a new melting furnace system, the experiments to keep the melting pool with minimal energy without throwing an auxiliary fuel and LOx was carried out. Also it is hoped that the results of the experiment will be available to analyze keeping a melting pool and behavior in a melting furnace.

• Nuclear Engineering and Technology
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• 제36권1호
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• pp.104-111
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• 2004

The melting temperatures of $UO_2,\;UO_2-6wt\%Gd_{2}O_3,\;UO_2-12wt\%Gd_{2}O_3,\;UO_2-2wt\%Er_{2}O_3,\;and\;UO_2-4wt\%Er_{2}O_3$ fuels were measured. Fuel materials were loaded in a tungsten capsule of which shape met the black body condition. The melting temperature was measured by the thermal arrest method during heating of the capsule in an induction furnace. The measured melting temperature of $UO_2$ fuel was $2815{\pm}20^{\circ}C$. The solidus and liquidus temperatures of $UO_2-Gd_{2}O_3\;and\;UO_2-Er_{2}O_3$ had also been measured, and it was observed that the solidus temperatures of them were lower than the liquidus temperature by $15{\sim}25^{\circ}C$. Measured melting temperatures of $UO_2,\;UO_2-Gd_{2}O_3\;and\;UO_2-Er_{2}O_3$ fuels were as follows:

• 한국안전학회지
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• 제8권4호
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• pp.139-148
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• 1993

Thermosyphons are simple devices that can passively transport thermal energy over relatively long distance with little temperature degradation. These attributes permit the use of low grade thermal energy for thermal control of structures including the snow melting and deicing to the pavement surface. The thermosyphon system requires no costly energy input and Is completely maintenance free. This paper presents the experimental results of the snow melting system in which thermosyphon was utilized to transfer the geothermal energy to the pavement to obviate slipping traffic accidents due to freezing of pavement in winter.

• 에너지공학
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• 제11권3호
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• pp.262-268
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• 2002

The present paper investigated the effect of ultrasonic vibrations on the melting process of phase-change materials (PCM). Furthermore, the present study considered constant heat-flux boundary condition, whereas many of the previous researches had adopted constant wall-temperature condition. The results of the present study revealed that ultrasonic vibrations accompanied the effects like acoustic streaming, cavitation, and thermally-oscillating flow. Such effects are a prime mechanism in the overall melting process when ultrasonic vibrations are applied. They speed up the melting process as much as 2.5 times, compared with the result of natural melting. Also, energy can be saved by applying ultrasonic vibrations to the natural melting. In addition, temperature and Nusselt numbers over time provided a conclusive evidence of the important role of ultrasonic vibrations on the melting phenomena.

• 한국주조공학회지
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• 제41권4호
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• pp.342-348
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• 2021

거의 모든 철계 주조공장은 생압고철 (press scrap)을 주 장입재로 사용한다. 본 연구에서는 생압고철의 형상, 크기를 최적화하여 용해에너지를 절감하고자 하였다. 주조공장 두 곳의 3t/h 중주파 유도용해로를 활용하여 실험하였다. 개선 조건의 경우, 초기 장입 시에는 맞춤형 생압고철을 사용하였고, 추가 장입 시에는 소형 생압고철을 사용하였다. 개선 조건의 에너지 절감 효과를 높이기 위해, 회수철 표면의 청정화 공정을 강화하여 실시하였다. 개선 조건에 의한 용해에너지 원단위 (melting energy basic unit) 절감률은 두 주조공장에서 각각 23.3, 23.9%였고, 거의 유사하였다. 원단위 수준이 다른 두 곳의 주조공장 모두에서 개선 조건은 매우 효과적이었다. 개선 조건의 에너지 절감 원리 및 경제적 효과를 기술하였다.

• 설비공학논문집
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• 제19권12호
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• pp.883-888
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• 2007

As a starting point of investigating what molecular dynamic simulations can reveal about the nature of atomic level of heating and cooling process, argon described by the LJ potential is considered. Stepwise heating and cooling of constant rates are simulated in the NPT (constant number, pressure and temperature) ensemble. Hysteresis is found due to the superheating and supercooling. Drastic change of volume and energy is involved with phase change, but the melting point can not be obtained by simply observing the changes of these quantities. Since liquid and solid phases can co-exist at the same temperature, Gibbs free energy should be calculated to find the temperature where the Gibbs free energy of liquid is equal to that of the solid since the equilibrium state is the state of minimum Gibbs free energy. The obtained melting temperature, $T^*=0.685$, is close to that of the experiment with only 2% error.

• 태양에너지
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• 제9권1호
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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.