• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.311-316
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• 2005

The experimental study for an operational characteristics and performance of the sodium heat pipe were carried out. For an experiment. the heat pipe which is 1000mm length and 25.4mm diameter of stainless steel container with 50 mesh of screen wick using sodium as a working fluid is manufactured and tested as functions of heat flow rate, inclined angle and operating temperature. The test results are as follows. During the start-up. frontal start up was observed because of the vapor density increasing as increased the hot zone. Also, the heat pipe showed uniform temperature over than $420^{\circ}C$ of the operating temperature. The average heat transfer coefficient increased as the heat flux and the vapor temperature increase, and the range of the total thermal resistance was 0.075-0.04 $^{\circ}C/W$ at the 12-53.55 $kW/m^2$ of heat flux and $500-750^{\circ}C$of operating temperature. The maximum heat flow rate was 750W at the 10 degree of top heating mode.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.68-73
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• 2011

An experimental study was conducted to investigate the thermal performance of a medium-temperature heat pipe against the charge amount of working fluid. The container and the wick of the heat pipe were made of stainless steel and the working fluid was Dowtherm-A for medium-temperature applications around $250^{\circ}C$. The diameter and length of the heat pipe were 25.4 mm and 1 m, respectively. The maximum thermal load was 1 kW and the working fluid charge ratio varied from 372% to 420%. The results showed that the thermal resistance ranged from 0.12 to $250^{\circ}C/W$ and the effective thermal conductance ranged from 7,703 to $8,898 W/m{\cdot}K$. Dry-out occurred for the heat pipe with 372% fill-charge at the heat load of 950 W, while the other heat pipes with higher charge amount did not encounter dry-out up to 1060 W.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1400-1405
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• 2004

Experimental study is performed to investigate the effect of heat load and operating temperature on the thermal performance of a heat pipe with screen mesh wick. The heat pipe was designed in 200 screen meshes, 500mm length and 12.7mm O.D tube of copper, water as working fluid(4.8g) and nitrogen as non-condensible gas(NCG). The heat pipe used in this study has evaporator, condenser and adiabatic section, respectively. Experimental data of axial wall temperature distribution is presented for heat transport capacity, the temperature of cooling water of condenser, inclination angle, and operating temperature. For the results from this study, it is found that, for the same charging mass of working fluid, the initial operating temperature and the overall wall temperatures of heat pipe are higher for NCG charging mass of $5.0{\times}10^{-6}kg$ and $3.4{\times}10^{-6}kg$, than that of $1.0{\times}10^{-6}kg$.

• International Journal of Air-Conditioning and Refrigeration
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• 제12권2호
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• pp.79-86
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• 2004

An analytical and experimental study has been conducted to determine the optimal charging mass of working fluid for the maximum heat transport capacity of heat pipe with axially grooved wick. When the heat pipe is operated in a steady state, the liquid-vapor meniscus recession of working fluid to the bottom of groove is occurred in the evaporator region. In this work, the optimal charging mass of working fluid was obtained by considering the meniscus recession from the axial variation of capillary pressure, the radius of curvature and wetting angle of meniscus of liquid-vapor interface. Experimental results were also obtained by varying the charging mass of working fluid within a heat pipe, and presented for the trend of maximum heat transport capacity corresponding to the operating temperature and the elevation of heat pipe. Finally, the analytical results of the optimal charging mass of working fluid were compared with those from the experiment, both of which were in good agreement with each other.

• Journal of Advanced Marine Engineering and Technology
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• 제35권8호
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• pp.1016-1021
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• 2011

열전소자를 이용한 냉각 장치에 있어서 열전소자발열부측의 제거 열량은 제품의 성능 및 적용범위를 결정하는 주요변수가 되므로 히트싱크의 열저항을 최소화 할 수 있는 최적 조건의 히트싱크 설계를 필요로 한다. 발열부가 작고 상대적으로 히트싱크 면적이 커서 히트싱크 전체면으로 열확산이 필요한 경우 히트싱크의 방열 성능을 향상시키기 위하여 작동유체 R-22의 진동형 히트파이프를 이용하여 열전소자의 발열부측의 발열량(30W, 60W, 80W, 100W)과 공기 유속(1~4 m/s)에 따른 히트싱크의 열저항 실험 및 수치해석 결과와 비교 분석을 통해 히트싱크의 냉각 성능을 향상 시킬 수 있는 방법을 연구하였다.

• Journal of Mechanical Science and Technology
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• 제14권10호
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• pp.1159-1167
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• 2000

Particles in liquid-solid suspension flow might enhance or suppress the rate of heat transfer and turbulence depending on their size and concentration. The heat transfer characteristics of liquid-solid suspension in turbulent flow are not well understood due to the complexibility of interaction between solid particles and turbulence of the carrier fluid. In this study, the heat transfer coefficients of liquid-solid mixtures are investigated using a double pipe heat exchanger with suspension flows in the inner pipe. Experiments are carried out using spherical fly ash particles with mass median diameter ranging from 4 to $78{\mu}m$. The volume concentration of solids in the slurry ranged from 0 to 50% and Reynolds number ranged from 4,000 to 11,000. The heat transfer coefficient of liquid-solid suspension to water flow is found to increase with decreasing particle diameter. The heat transfer coefficient increases with particle volume concentration exhibiting the highest heat transfer enhancement at the 3% solid volume concentration and then gradually decreases. A correlation for heat transfer to liquid-solid flows in a horizontal pipe is presented.

• 태양에너지
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• 제11권1호
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• pp.78-86
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• 1991

내부에 삼각형 핀을 갖는 회전형 히트파이프의 작동유체로 물-에탈올 2성분 유체를 사용하였을때 Nusselt의 막응축이론을 기초로 하여 핀 및 그루브의 전열특성을 유한요소법에 의한 수치해석을 하였으며 또한 실험을 행하여 비교하였다. 히트파이프의 회전수가 증가할수록, 내부 증기압이 높을수록 전열량은 완만하게 증가하지만 에탄올 농도가 커 질수록 전열량은 감소하였다. 그리고 순수 에탄올만을 작동유체로 하는 경우는 증류수만을 작동유체로 하는 경우의 전열량의 $0.75{\sim}0.85$정도로 나타났다. 또한 에탄올 농도가 0. 2전후에서 전열효과 및 작동온도 범위 등이 가장 유리하게 나타났다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2124-2129
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• 2007

A VCHP was fabricated and tested for its thermal performance. The container was made of copper, and the working fluid was water. STS-316 screen of mesh number 100 was inserted as a capillary structure. As a baseline performance, a normal heat pipe of the same dimensions was tested in advance to compare with VCHP, where an inert gas container was attached. The outer diameter of the heat pipe was 12.8 mm and the total length was 600 mm. The evaporator and the condenser lengths were both 200 mm. The thermal load ranged from 20 to 300W. Typical result revealed that the operating temperature of the VCHP stayed almost constant, while that of the normal heat pipe varied as much as 40$^{\circ}C$. Therefore, it was demonstrated that the VCHP is very effective for temperature control of heat-dissipating devices.

• Journal of Advanced Marine Engineering and Technology
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• 제8권1호
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• pp.4-16
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• 1984

The heat-pipe is characterised by the highly effective thermal conductance. In order to change the thermal conductance, the heat-pipe is connected to a reservior having a space which is filled with non-condensable gas. In normal operation, the vapour of working fluid will tend to pump the non- condensable gas into the reservoir and the gas-vapour interface situates at some point along the condenser section. The thermal conductance is affected by non- condensable gas. It is concluded that the suitable position of interface can be used to control the temperature of condenser section. In this experiment, the evaporating part is connected to the lowest position of heat-pipe. The copper heat-pipe which is filled with Freon-113 or distilled water as working fluid utilized. As results of experimental study, thermal conductance can be increased by the operating pressure which is infulenced by non-condensable gas. A correlative equation between the thermal conductance and the mass of non- condensable gas is also obtained.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.443-444
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• 2006

The influence of the heat sources on LED junction temperature are Engine room air, Back plate, Electric power device, and so on. LED lamp cooling system is considered to be an important subject fur high light efficiency. Because LED Chip will be problem When LED junction temperature be over $135^{\circ}C$, In this Study, The Looped Heat Pipe System is considered to prevent LED Chip fall. The LHPS is consist of evaporator part, condenser part, heat pipe part. The working fluid of LHPS is HCFC-123. In this study, to prevent LED Chipfall, we study thermal characteristics for Looped Heat Pipe System with LED lamp.