• 설비공학논문집
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• 제14권11호
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• pp.880-889
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• 2002

The purpose of the present study is to examine the factors affecting the heat transfer limitations of screen mesh heat pipe for electronic cooling by theoretical analysis. Diameter of pipe was 6 mm, and mesh numbers are 50, 100, 150, 200 and 250 and water was selected as a working fluid. According to the change of mesh number, wick layer, inclination and saturation temperature, capillary pressure, pumping pressure, liquid friction coefficient in wick, vapor friction coefficient, capillary limitation, entrainment limitation, sonic limitation and boiling limitation we analyzed by theoretical design method of a heat pipe. As some results, the capillary limitation in small diameter of heat pipe is largely affected by mesh number and wick layer.

• 한국항공우주학회지
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• 제33권9호
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• pp.97-103
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• 2005

본 연구에서는 소형 동-소결윅 히트파이프를 대상으로 소결윅의 구조적 인자들이 히트파이프의 열수송 한계에 미치는 영향을 이론적으로 분석하였다. 소결윅의 입자 크기의 균일성과 소결 조건이 전체적인 기공분포와 기공률을 포함한 물리적 특성에 지배적인 요소로 작용했으며, 윅 두께 및 기공의 작은 편차가 히트파이프의 열수송 한계에 대체로 큰 영향을 미치는 것으로 나타났다. 특히, 증기온도와 경사각에 따라서 윅 두께와 평균 입자 반경, 그리고 모세관반경의 미세한 변화가 히트파이프의 모세관한계를 현저하게 변화시켰다.

• Communications for Statistical Applications and Methods
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• 제17권1호
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• pp.47-54
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• 2010

By using the white noise theory for fractional Brownian sheet, we give new representations of the Wick integrals of various types with respect to fractional Brownian sheet with Hurst parameters $H_1,H_2{\in}$(0, 1).

• 설비공학논문집
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• 제13권1호
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• pp.18-24
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• 2001

Woven wire wick is very effective structure because of its easiness to insert inside of pipe for a miniature heat pipe. The present study was conducted to investigate the effect of the effective flow passage with respect to wire helix angle. Also effective thermal conductivity were examined by defining mean porosity considering effective liquid flow passages. Effective heat transfer area is varied with respect to wire helix angle, and in the range of $\thet=60~65^{\circ}C$, heat transfer area is decreased about 15~20%. Permeability of woven wire wick shows similar value of 200 mesh screen wick. And comparison of experimental results on effective thermal conductivity shows a fairly good agreement with the analytical results.

• 설비공학논문집
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• 제12권10호
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• pp.894-900
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• 2000

The experimental study for performance improvement of aluminum/freon22 grooved heat pipe was carried out. Arterial wick was used for performance improvement of heat pipe. The experimental result was compared with screen covered grooved wick heat pipe. And also, performance test of grooved wick thermosyphon inserted straight wire in the center of grooved pipe was carried out. This result was compared with the performance test result of grooved wick thermosyphon. The operation limit of artery inserted grooved heat pipe was slightly extended, but thermal resistance of this heat pipe was twice as large as that of screen covered grooved heat pipe. In case of thermosyphon, the operation limit of grooved thermosyphon inserted straight wire in the center of grooved pipe was slightly extended, but thermal resistance was increased, comparing with that of the grooved thermosyphon.

• 한국태양에너지학회 논문집
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• 제22권4호
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• pp.18-25
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• 2002

For application to medium temperature solar collerctors $(80\sim120^{\circ}C)$, a heat pipe should be designed properly to efficiently transfer heat to a hotter condenser than common applications. Among many wick structure candidates for heat pipes of this type, a slab wick was selected based on promising performance data reported previously. The thermal performance of slab wick heat pipes, screen wick heat pipes and thermosyphons with enlarged condenser section were experimentally investigated for comparison purpose. The heat pipes were 8.0 mm O.D. (evaporator section) and 25.4 mm O.D. (condenser section) made of copper. The experimental data of the heat pipes were analysed in terms of thermal resistance against thermal load and coolant temperature.

• 대한설비공학회지:설비저널
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• 제15권3호
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• pp.273-282
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• 1986

The purpose of this research was to study the characteristics of heat transfer in Heat Pipe which used the composition wick of screened groove - metallic mesh by ADI method and experimental results. As the results, the more than number of metallic mesh screen layers in a heat pipe increased, the fewer the effect of heat recovery decreased. In case of 1 - layer metallic mesh screen wick, the response of the effect in heat recovery was more rapidly showed than in case of other layers and in spite of high load, the evaporation section of Heat pipe with 1 - layer metallic mesh screen wick showed the stable response and did not show excessive super heat. There was a interrelation between thermal resistance and the variable layers, between thermal resistance and the variable gaps of metallic meshes, the heat transfer characteristics of Heat pipe were depended on the thermal resistance of composition wick.

• International Journal of Air-Conditioning and Refrigeration
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• 제12권1호
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• pp.1-9
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• 2004

The purpose of the present study is to examine the heat transport limitations in a screen mesh heat pipe for electronic cooling by theoretical analysis. Diameter of pipe was 6mm, and mesh numbers were 50, 100, 150, 200 and 250, and water was investigated as working fluid. According to the change of mesh number, wick layer, inclination and saturation temperature, the maximum heat transport limitations by capillary, entraintment, sonic and boiling were analyzed by a theoretical design method of heat pipe, including capillary pressure, pumping pressure, liquid friction coefficient in wick, vapor friction coefficient, etc. Based on the results, the capillary limitation in a small diameter of heat pipe is largely affected by mesh number and wick layer. Mesh number of 250 is desirable not to be used in pipe diameter of 6 mm, because capillary heat transport limitation decreases by the abrupt increase of liquid friction pressure due to the small liquid flow area. For the heat transport of 15 watt in 6mm diameter pipe, mesh number of 100 and one layer is an optimum wick condition, which thermal resistance is the smallest.

• 대한기계학회논문집B
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• 제26권11호
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• pp.1630-1637
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• 2002

A slab-wick heat pipe was fabricated and tested for applications where the condenser temperature is in a range of 80 to 12$0^{\circ}C$. The pipe material was 9.53 mm O.D. copper tube and the working fluids were ethanol and water. The total length of the heat pipe was 1.6 m, in which evaporator section was 1.4 m and the condenser was 0.10 m. The slab was a composite wick structure fabricated with STS316 wire screens. Thermal load was varied for a specified fill charge ratio and inclined angle. The optimum fill charge ratio was identified to be 110% based on a theoretical calculation of the pore space in the slab wick of the heat pipe. The maximum thermal load was 120W for ethanol and the same was 200W for water with the condenser temperature of 8$0^{\circ}C$. The thermal performance of the slab wick heat pipe is analysed in terms of temperature characteristics and thermal resistance against thermal load, tilt angle and fill charge ratio.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1710-1716
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• 2008

The Loop Heat Pipe (LHP) operates to pump the working fluid by means of the capillary force in a wick structure. Particularly, it is difficult to design and manufacture the evaporator consisted of a grooved container and a compensation chamber as well as the wick structure. This study is related to design and manufacture the grooved container coupled with wick structure, the properties of the wick structure such as the permeability, the porosity, and the maximum capillary pressure were measured to apply the cooling technology for Insulated Gate Bipolar Transistor (IGBT). The container of the LHP was manufactured by the electrical discharge process and the wick structure was sintered with the nickel particle by an axial-press apparatus with the pulse electronic discharge. As results, the properties of the wick were experimentally obtained about 60% of the porosity, 35kPa of the maximum capillary force and $1.53{\times}10-13m2$ of the permeability.