• Journal of Mechanical Science and Technology
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• 제17권10호
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• pp.1507-1519
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• 2003

The two-phase flow patterns for both non-loop and loop type oscillating capillary tube heat pipes (OCHPs) were presented in this study. The detailed flow patterns were recorded by a high-speed digital camera for each experimental condition to understand exactly the operation mechanism of the OCHP. The design and operation conditions of the OCHP such as turn number, working fluid, and heat flux were varied. The experimental results showed that the representative flow pattern in the evaporating section of the OCHP was the oscillation of liquid slugs and vapor plugs based on the generation and growth of bubbles by nucleate boiling. As the oscillation of liquid slugs and vapor plugs was very speedy, the flow pattern changed from the capillary slug flow to a pseudo slug flow near the annular flow. The flow of short vapor-liquid slug-train units was the flow pattern in the adiabatic section. In the condensing section, it was the oscillation of liquid slugs and vapor plugs and the circulation of working fluid. The oscillation flow in the loop type OCHP was more active than that in the non-loop type OCHP due to the circulation of working fluid in the OCHP. When the turn number of the OCHP was increased, the oscillation and circulation of working fluid was more active as well as forming the oscillation wave of long liquid slugs and vapor plugs in the OCHP. The oscillation flow of R-142b as the working fluid was more active than that of ethanol and the high efficiency of the heat transfer performance of R -142b was achieved.

• 한국소음진동공학회논문집
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• 제20권1호
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• pp.45-50
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• 2010

In the refrigerator, the two-phase refrigerant-induced noise of the capillary tube in an evaporator-inlet pipe has been a great concern. The capillary tube is usually covered with insulation-foam packed in the space between inner and outer cabinets without any vibration isolation. Therefore, the refrigerant-induced vibration of the capillary tube can be easily transferred to the outer cabinet, which may increase the radiated noise. In this paper, the characteristics of transferred vibration through the insulation-foam are investigated experimentally by using the refrigerantsupplying equipment. The frequency characteristics, such as dynamic Young's modulus and loss factor, of the insulation-foam are also discussed.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.479-482
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• 2006

The most the electronic industry has recently accelerated the modularization, the miniaturization and the high integrated trend of electronics fields such as electronics components, appliances and etc., the most increasingly the heat generation problem rises. Even though the conventional cooling technologies are widely used in order to reduce the heat loads, the technologies are not easy to meet the present trends due to the fact that most of many conventional methods are relative to external form environments such as size, design and so on. With regardless of those environments, however, a heat pipe is one of the most efficient systems to improve the heat transfer performance. And then the performance of the heat pipe depends on a wick structure. Of various wick structures, sintered metal wick is known so that it has some advantages such as smaller pore size, increasing porosity as well as high reliability. In this study sintered metal wicks, thickness 0.7 mm, 0.8 mm and 0.9 mm, were manufactured as of $100{\mu}m$ copper powder to obtain the manufacturing technology of heat pipes mounted with a sintered metal wick. Furthermore, experiments for the operational performance factors such as capillary limit, thermal resistance were not only performed but also compared with a theoretical model simultaneously. Experimental results agreed with the theoretical model, and then it seems to be required to study various development processes of sintered metal wicks for the high performance of a heat pipe system.

• 센서학회지
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• 제13권5호
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• pp.378-382
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• 2004

A micromachined fluidic structure for the introduction of liquid samples into a chip-based sensor array composed of individually addressable polymeric microbeads has been developed. The structure consists of a separately attached cover glass, a single silicon chip having micromachined channels and microbead storage cavities, and a glass carver. In our sensor array, transduction occurs via colorimetric and fluorescence changes to receptors and indicator molecules that are covalently attached to termination sites on the polymeric microbeads. Data streams are acquired for each of the individual microbeads using a CCD. One of the key parts of the structure is a passive fluid introduction system driven only by capillary force. The velocity of penetration of a horizontal capillary for the device having a rectangular cross section has been derived, and it is quite similar to the Washburn Equation calculated for a pipe with a circular cross section having uniform radius. The test results show that this system is useful in a ${\mu}$-TAS and biomedical applications.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.178-181
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• 2008

Cylindrical stainless-steel/sodium heat pipe for a high-temperature application was manufactured and tested for transient and steady-state operations. The container material was made of stainless-steel 316, and the working fluid was sodium. Stainless-steel 316 mesh screen was inserted as a capillary structure. The working fluid fill charge ratio was approximately 64 $\sim$ 181% based on the pore space of the wick. The outer diameter of the heat pipe was 12.7 mm and the total length was 250 mm. The evaporator part was 150 mm and the condenser 80 mm. The performance test of the heat pipe has been conducted in the furnace with up to 800 W. The variation of the average heat transfer coefficient was investigated as a function of heat flux and vapor temperature. As input thermal load increased, it was showed that difference of temperatures in evaporator and condenser decreased and that operating section and heat transfer characteristics at the heat pipe increased.

• Journal of Advanced Marine Engineering and Technology
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• 제33권8호
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• pp.1144-1151
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• 2009

냉동기는 비단열모세관을 채택하여 사용함으로써 사이클의 효율을 향상시킬 수 있다. 비단열모세관은 모세관과 흡입관을 접합함으로써 둘 사이에 열전달이 일어날 수 있도록 한 장치로서 SLHX 라고 부른다. 두 관을 접합하는 방법은 다양하며 이는 사이클의 성능에 영향을 미칠 수 있다. 본 연구에서는 가장 널리 사용되는 두 가지 접합방법이 냉동사이클에 미치는 영향을 해석하였다. 실험결과 용접형 SLHX의 열저항이 테이프형 SLHX의 열저항 보다 크게 작은 것으로 나타났다. 이를 이용한 사이클해석 결과 용접형 SLHX는 COP 와 냉동능력을 5.09%와 14.77% 향상시키고 테이프형 SLHX는 각각 5.05%와 14.75% 향상시켜 둘 사이의 차이는 매우 작은 것으로 나타났다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1241-1246
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• 2004

The heat flux on a chip is rapidly increasing with decreasing the size of one. It is necessary to properly cool the high heat flux chip. One of the promising cooling methods is to apply CPL heat pipes with porous materials, for example PVA, polyethylene, and powder sintered metal plate and with microchannels in the evaporator. A small scale CPL heat pipe with PVA as wick was designed and manufactured. Since the height difference between the evaporator and the condenser is a crucial parameter in the CPL heat pipes, the performance of the heat pipes depending on the parameter was investigated. The parameter is higher the performance is better. However, the improvement rate of the performance does not increase the increase rate of the height. In addition to, the parameter effect depending on heat input was investigated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1499-1505
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• 2003

Rapid development of electronic technology requires small size, high density packaging and high power of electronic devices. So, in this paper, characteristics on oscillating heat pipe according to operating conditions(environment temperature, charging ratio of working fluid, inclination) based on experimental study was investigated. From the experimental results, $25^{\circ}C$environment temperature), R-141b(working fluid)40%(charging ratio) was best performace at others of inclination angle and The top heating mode of OCHP performed 80% efficiency of the bottom heating mode.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 추계학술발표대회 논문집
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• pp.220-225
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• 2008

Cylindrical stainless-steel/sodium heat pipe for a high-temperature solar thermal application was manufactured and tested for transient and steady-state operations. Two layers of stainless-steel screen mesh wick was inserted as a capillary structure. The outer diameter of the heat pipe was 12.7 mm and the total length was 250 mm. The effective heat transport length, the thermal load, and the operating temperature were varied as thermal transport conditions of the heat pipe. The thermal load was supplied by an electric furnace up to 1kW and the cooling was performed by forced convection of air The effective thermal conductivity and the thermal resistance were investigated as a function of heat flux, heat transport length, and vapor temperature. Typical range of the total effective thermal conductivity was as low as 43,500 W/m K for heat flux of 176.4 kW/$m^2$ and of operating temperature of 1000 K.

• 대한기계학회논문집B
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• 제26권9호
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• pp.1260-1266
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• 2002

In this study, to make an excellent heat pipe, the manufacturing technology of a sintered wick was investigated. Making a sintered wick is known to be very difficult but it has many advantages. For example, the porosity and pore size can be controlled and the capillary force is great. The mixture of copper and pore former powder was used as a wick material and ceramic-coated stainless steel was used as a mandrel which is necessary for vapor flow. To analyze the feature of the manufactured wick, not only porosity and pore size were measured but also the sintered structure was observed. A heat pipe with sintered wick was manufactured and the performance test of the heat pipe was performed in order to review cooling performance. The performance test results for the 4mm diameter heat pipe with the sintered wick shows the stability since the temperature difference between a evaporator and a condenser of the heat pipe is less than 4.4$^{\circ}C$, and thermal resistance is less than 0.7$^{\circ}C$/W, In the meantime the composite wick that is composed with sintered and woven wire was also examined. The heat transfer limit of the heat pipe with composite wick was enhanced about 51%~60% compare to the one with sintered wick.