• ETRI Journal
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• 제33권4호
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• pp.645-647
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• 2011

In this study, a microcapillary pumped loop (MCPL) that can be used as a cooling device for small electronic and telecommunications equipment has been developed. For thin devices such as an MCPL, securing a vapor flow space is a critical issue for enhancing the thermal performance. In this letter, such enhancement in thermal performance was accomplished by eliminating condensed droplets from the vapor line. By fabricating the grooves in the vapor line to eliminate droplets, a decrease in thermal resistance of about 63.7% was achieved.

• 설비공학논문집
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• 제16권12호
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• pp.1107-1116
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• 2004

In this paper, the effects of diverse parameters on the operation of loop heat pipe (LHP), such as particle diameter of sintered porous wick, wick porosity, vapor line diameter, thickness of wick and heating capacity were investigated by a theoretical analysis. A LHP has a wick only in its evaporator for the circulation of working fluid, and utilizes a porous wick structure of which pore size is very small to obtain a large capillary force. The working fluid is water and the material of sintered porous wick is copper. For these different parameters, capillary pressure, pressure drop in wick, pressure drops and temperature distribution were analyzed by a theoretical design method of LHP.

• Korean Chemical Engineering Research
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• 제43권2호
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• pp.259-265
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• 2005

Water+n-methylformamide(NMF), benzene+NMF 그리고 toluene+NMF의 353.15 K 이성분계 등온 기-액상평형을 headspace gas chromatography(HSGC)로 측정하였고, NMF+benzene+n-heptane과 NMF+toluene+n-heptane 삼성분계에 대한 298.15 K 액-액상평형을 tie-line 측정법으로 결정하였다. 이성분계 기-액상평형 데이터는 공비점이 없었으며, $g^E$ 모델식(Margules, van Laar, Wilson, NRTL, UNIQUAC)에 비교적 작은 편차로 잘 상관되었다. 삼성분계 tie-line 데이터는 NRTL식과 UNIQUAC식을 이용하여 상관과 추산을 병행하였으며, Hirata-Fujita식과 Maior-Swenson식을 이용하여 정확도를 검증하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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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.

• 대한화학회지
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• 제51권6호
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• pp.577-584
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• 2007

본 연구에서는 대기 중에서 물의 증발이나 얼음의 승화와 같은 물의 상태 변화를 물의 상평형 그 림을 이용하여 어떻게 설명할 수 있는지를 제시하고자 하였다. 물의 상평형 그림은 1성분계의 상평형을 나타 낸 것이므로 원칙적으로 물만 존재하는 경우에 사용할 수 있는 것이다. 공기가 존재하는 경우에는 액체 물 또 는 고체 얼음이 있으면 항상 공기 중에 수증기가 공존하게 되며, 이 때 물 또는 얼음의 압력은 공기 중 수증 기의 부분 압력과 일치하지 않기 때문에 상평형 그림에 하나의 점으로 그 상태를 나타낼 수 없다. 그러나 공 기가 존재하는 경우에도 포화 수증기압은 물만 존재하는 경우와 거의 차이가 없으므로 상평형 그림의 증기 압 력 곡선과 승화 곡선을 이용하여 대기 중에서 물의 증발과 얼음의 승화를 설명할 수 있음을 논의하였다.

• E2M - 전기 전자와 첨단 소재
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• 제9권8호
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• pp.776-782
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• 1996

The electrical properties of vapor deposition polymerized polymide thin films for getting an in-line system with manufacturing process of semiconductor device, have been studied. Polyimide thin films fabricated by vapor deposition polymerization(VDP) method based on PMDA and 4,4'-DDE monomer were confirmed by FT-IR spectra. It is found that the major conduction carriers of thin films are ions, and the hopping length of ions is almost same with monomer length at the temperature over 120.deg. C through the analysis of electrical conduction mechanism. Also, The activation energy is about 0.69 eV at the temperature of >$30^{\circ}C$ - >$150^{\circ}C$ and it is shown that the resistivity at which thin films can be used as an insulating film between layers of semiconductor device, is 3.2*10$^{15}$ .ohm.cm.

• 대한기계학회논문집B
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• 제33권5호
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• pp.373-380
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• 2009

The evaporation process of multi-component fuel is different from one of a single component, because the properties of each component affects among the components. In actual engine, the spatial distribution of fuel vapor concentration dominates auto-ignition and initial combustion, and depends on the volatility and diffusivity of each component fuel contained in the multi-component fuel. Then, this study proposes a simplified numerical scheme for analysis of evaporation process of multi-component fuel sprays. Evaporation process is calculated by KIVA-II code based on the simple two-phases region that is approximated by modified saturated liquid-vapor line, which was obtained by connecting the 50% distillation temperature for each component under several pressure fields. Consequently, it can be quantitatively simulated that vapor of low boiling fuel component mostly exists around nozzle and spray tip region, the high boiling duel component, on the other hand, mostly appears near the spray tip.

• 한국분무공학회지
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• 제28권3호
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• pp.113-118
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• 2023

This study investigates the evaporation characteristics of paired sessile droplets on a heated substrate. In particular, the evaporation time and contact line behaviors were analyzed based on the droplet-to-droplet distance and substrate temperature. The contact line behavior and volume variations were visualized using the shadowgraph method. It was observed that the contact diameter and contact angle exhibited similar behavior for both single and paired droplets regardless of the droplet-to-droplet distance and substrate temperature. The paired droplets demonstrated a longer evaporation time than the single droplet due to the vapor accumulation between the droplets. Furthermore, the scaled lifetime, defined as the ratio of evaporation time between paired and single droplets, increased as the droplet-to-droplet distance decreased and decreased as the substrate temperature increased, attributed natural convection.

• 한국표면공학회지
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• 제52권6호
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• pp.357-363
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• 2019

We investigated a synthesis yield and diameter distribution of single-walled carbon nanotubes (SWNTs) with respect to the growth position in a horizontal chemical vapor deposition (CVD) chamber. Thin films and line-patterned Fe films (0.1 nm thickness) were prepared onto ST-cut quartz substrates as catalyst to compare the growth behavior. The line-patterned samples showed higher growth density and parallel alignment than those of the thin film catalyst samples. In addition, line density of the aligned SWNTs at central region of the chamber was 7.7 tubes/㎛ and increased to 13.9 tubes/㎛ at rear region of the CVD chamber. We expect that the enhanced amount of thermally decomposed feedstock gas may contribute to the growth yield enhancement at the rear region. In addition, the lamina flow in the chamber also contribute to the perfect alignment of the SWNTs based on the value of gas velocity, Reynold number, and Knudsen coefficient we employed.

• International Journal of Air-Conditioning and Refrigeration
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• 제13권3호
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• pp.119-127
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• 2005

Liquid pressure amplifiers have been proposed as an energy saving technology for vapor compression refrigeration systems configured with direct-expansion evaporators. The technology utilizes a refrigerant pump in the high pressure liquid line as a means of maintaining a suitable pressure differential across the expansion valve while lowering condensing pressure to achieve the reduction of compressor energy consumption. Applications have been proposed on systems ranging from small unitary air-conditioning to large supermarket and commercial refrigeration systems. This paper clarifies the role of such a device in a vapor compression refrigeration system. Limitations are presented and discussed. Finally, results of detailed analyses are presented to quantify the energy consumption both with and without a liquid pressure amplifier in a unitary air conditioning system. The estimated energy savings associated with the installation of a liquid pressure amplifier are minimal.