• 제목/요약/키워드: LHP

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Study on a Operating Characteristics of Loop Heat Pipe Using a Brass Sintered Metal Wick-Water (황동소결윅-물 LHP의 작동 특성에 관한 연구)

  • Lee, Wook-Hyun;Lee, Ki-Woo;Park, Ki-Ho;Lee, Kye-Jung;Noh, Seung-Young
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1528-1533
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    • 2004
  • In this study, we have manufactured the LHP(Loop Heat Pipe) with sintered metal wick and investigated the working characteristics of LHP experimentally.Water was used as a working fluid and fill charge rate was changed. LHP basically consist of the separated vapor/liquid channels, evaporator having sintered metal wick(effective pore diameter :$16{\sim}19{\mu}m$), and condenser cooled by water. The diameter of vapor/liquid line tube are 3.2mm/6.35mm, respectively. Heat transfer rate and thermal resistance was represented to study the basic characteristics of LHP at each conditions

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Design Optimization for Loop Heat Pipe Using Tabu Search (Tabu Search를 이용한 Loop Heat Pipe의 최적설계에 관한 연구)

  • Park, Yong-Jin;Yun, Su-Hwan;Ku, Yo-Cheun;Lee, Dong-Ho
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.8
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    • pp.737-743
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    • 2009
  • Design optimization process and results of Loop Heat Pipe(LHP) using Tabu Search have been presented in this study. An objective of optimization is to reduce a mass of the LHP with satisfying operating temperature of a Lithium Ion battery onboard an aircraft. The battery is assumed to be used as power supply of air borne high energy laser system because of its high specific energy. The analytical models are based on a steady state mathematical model and the design optimization is performed using a Meta Model and Tabu Search. As an optimization results, the Tabu search algorithm guarantees global optimum with small computation time. Due to searching by random numbers, initial value is dominant factor to search global optimum. The optimization process could reduce the mass of the LHP which express the same performance as an published LHP.

Sintered Metal Wicks Development for the High Performance Loop Heat Pipe(LHP) Systems

  • Choi, Jee-Hoon;Sung, Byung-Ho;Yoo, Jung-Hyun;Seo, Min-Whan;Kim, Chul-Ju
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2136-2141
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    • 2007
  • The Loop Heat Pipe(LHP) system uses capillary forces so as to pump the working fluid from heat acquisition to heat rejecting systems. The performance of the LHP systems depends mainly upon the operating performance of the wick structure. The capillary pressure increases with decreasing the pore size of the wick structure. By the way, the wick structure's permeability decreases with decreasing the pore size and the porosity. To obtain an ideal wick, the wick structure should possess several characteristics such as the small pore size, high porosity and chemical compatibility with working fluid. Sintered metal wicks have been mainly used as the capillary wick structure mounted in LHP because of the fact that the sintered metal wick has some advantages like convenient selection of wick material, smaller pore size and so on as well as high reliability. In this study, sintered metal wicks were developed to meet required several parameters to design the high performance LHP systems for obtaining even more effective cooling technologies.

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Analytical Modeling of a Loop Heat Pipe with a Flat Evaporator by Applying Thin-Film Theory (평판형 증발부를 갖는 루프히트파이프에 대해 박막이론을 적용한 해석적 모델링)

  • Jung, Eui-Guk;Boo, Joon-Hong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.12
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    • pp.1079-1085
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    • 2010
  • A steady-state analytical model was presented for a loop heat pipe (LHP) with an evaporator that has a flat geometry. On the basis of a series of reviews of the relevant literature, a sequence of calculations was proposed to predict the temperatures and pressures at each important part of the LHP: the evaporator, liquid reservoir (compensation chamber), liquid line, vapor line, and condenser. The analysis of the evaporator, which is the only part in the LHP that has a capillary structure, was emphasized. Thin-film theory is applied to account for the pressure and temperature in the region adjacent to the liquid-vapor interface in the evaporator. The present study introduced a unique method to estimate the liquid temperature at the interface. Relative freedom was assumed in the configuration of a condenser with a simplified liquid-vapor interface. Our steady-state model was validated by experimental results available in the literature. The relative error was within 3% on the absolute temperature scale, and reasonable agreement was obtained.

Theoretical Analysis of the Pressure Drop in Loop Heat Pipe by Sintered Porous Wick Structure (다공성소결윅구조에 따른 루프 히트파이프에서 압력손실의 이론적 분석)

  • Lee, K.W.;Lee, W.H.;Park, K.H.;Lee, K.J.;Chun, W.P.;Ihn, H.M.
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1225-1230
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    • 2004
  • In this paper, the pressure drops were investigated according to the sintered porous wick structure in loop heat pipe(LHP) by theoretical analysis. LHP has the wick only in evaporator for the circulation of working fluid, so utilizes porous wick structure which pore diameter is very small for large capillary force. This paper investigates the effects of different parameters on the pressure drops of the LHP such as particle diameter of sintered porous wick, wick porosity, vapor line diameter, thickness of wick and heating capacity. Working fluid is water and the material of sintered porous wick is copper. According to the these different parameters, capillary pressure, pressure drop in wick were analized by theoretical design method of LHP.

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Operating Characteristics of a Sintered-Metal Wick/Methanol Loop Heat Pipe Having a Bypass Line (소결금속 윅과 메탄올을 사용하며 바이패스라인이 부착된 루프히트파이프의 작동 특성)

  • Boo, Joon-Hong;Jung, Eui-Guk
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2130-2135
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    • 2007
  • Operating characteristics of a loop heat pipe (LHP) having a bypass line was investigated experimentally. The LHP had a sintered metal wick as a capillary structure and methanol as a working fluid. The sintered metal wick was made of stainless steel of which the average pore size was 5 ${\mu}m$and porosity of 47%. A bypass line of a small diameter was attached between the vapor escape passage and the liquid reservoir. The dimension of the flat evaporator was $50(L){\times}40(W){\times}30(H)$ mm and that of the condenser was $50(L){\times}40(W){\times}11(H)$ mm. Wall and pipe material of the LHP was stainless steel and heating area was 35(W) mm${\times}$35(L) mm. The inner diameters of vapor and liquid transport lines were 4.0 mm and 2.0 mm, and the lengths of the two lines were both 0.5 m. The LHP was tested for three different tilt angles of horizontal, favorite tilt, and adverse tilt. The thermal load range was up to 290 W at the condenser above evaporation position. Furthermore, the effect of a bypass line on the start-up transient as well as steady-state operation was presented and discussed.

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A Study on the Reduction the Thermal Contact Resistances at the Interface Between a Porous Metal Wick and Solid Heating Plate for a Circular Plate LHP (원판형 LHP 증발부의 소결 금속 윅에서의 접촉 저항에 관한 연구)

  • Jo, Jung-Rae;Choi, Jee-Hoon;Sung, Byung-Ho;Ki, Jae-Hyung;Ryoo, Seong-Ryoul;Kim, Chul-Ju
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.2357-2362
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    • 2008
  • LHP is different from a conventional heat pipes in design and heat and fluid flow passages. The situations of the former is much complex than the latter. In LHPs, evaporation occurs at the contact interface between the heating plate and the porous wick, so some micro channels machined at the contact interface serve to let the vapor flow out of the evaporator. This complexity of contact geometry was known to cause a high resistance to heat flow. The present work was to study the problem of heat passage across the contact surface for LHPs and determine those values contact resistance. For two cases of contact structures, the thermal contact resistances were examined experimentally, one being obtained through mechanical contact under pressure and the other through sintered bonding. Nickel powder wick and copper plate were used for specimens. The result showed that a substantial reduction of contact resistance of an order of degree could be obtainable by sintered bonding.

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Safety Design of the Loop Heat Pipe (LHP) by the Hazard Analysis

  • Tanaka, Kiyoshi
    • International Journal of Safety
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    • v.9 no.1
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    • pp.54-57
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    • 2010
  • The LHP uses the capillary head instead of the mechanical pump to transfer the fluid. It does not have any moving parts and transfer the fluid by the capillary head between the vapor and liquid interface of the wick like a heat pipe (HP). Moreover, vapor and liquid flows in the same direction. It can reduce the loss of the pressure in the wick (very short wick in the evaporator) and can transfer large heat over long distance compared with HP. It is necessary that we do the hazard analysis that is a part of the safety design, for the benefit of eliminating and inhibit the hazard. In this paper, we describe the hazard analysis of LHP.

Comparison of Li-heparinized Versus Na-fluorinated Plasma for Routine Blood Glucose Determination Using Hexokinase Procedure (Hexokinase 방법을 이용한 Heparin 혈장과 NaF 혈장 시료의 혈당 분석치 비교)

  • Moon, In-Kyung
    • Korean Journal of Clinical Laboratory Science
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    • v.39 no.1
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    • pp.25-30
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    • 2007
  • In this study, the two sampling methods for blood glucose measurement were evaluated in order to reduce pre-analytical error. For this purpose, glucose levels of Li-heparinized plasma (LHP) and Na-fluorinated plasma (NFP) in blood collected from healthy volunteers were determined by using routine hexokinase procedures. The percentage range of pre-analytical error was quantitated by comparing LHP glucose values with NFP glucose values according to delaying analytical time (0, 60, and 120 min). LHP glucose values were decreased by 6.6% in 60 min., 17.7% in 120 min, whereas NFP glucose values decreased by 1.1% in 60 min, 2.0% in 120 min. Therefore it may be recommended that the NFP sampling method should be used for routine blood glucose determination in diabetes mellitus diagnosis.

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A Study on Selecting Criteria of Working Fluid in Loop Heat Pipes with a Circular Plate Type Evaporator

  • Nguyen, Xuanhung;Sung, Byung-Ho;Choi, Jee-Hoon;Jo, Jung-Rae;Yim, Kwang-Bin;Kim, Chul-Ju
    • Proceedings of the SAREK Conference
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    • 2008.06a
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    • pp.309-314
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    • 2008
  • increased heat dissipation and higher heat density of electronic equipment and/or parts released. A loop heat pipe(LHP) has been payed closer attention to the potential candidate of an electronic cooling. As of the LHP with a circular plate type evaporator developed, this study focused on its operating characteristics on the steady state in accordance with charging different working fluid. The relationship between working fluid and operating characteristics is discussed.

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