• Proceedings of the KSME Conference
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• 2005.11a
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• pp.5.1-5.1
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• 2005

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.29 no.9
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• pp.79-82
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• 2000

동관은 열전달성, 내식성, 가공성이 우수하여 각종 열교환기용 열전달관으로 각각의 열전달특성요구에 맞게 가공되어 사용되고 있다. 최근 제품가격의 하락에 따라 열전달특성 개선 뿐만아니라 코스트다운에 대한 요구도 커지고, 또 냉매도 HFC계로 변화하고 있어 새로운 관점에서 열전달관개발을 하여야 한다. 일본의 Kobe제강소는 1917년부터 동관을 제조하기 시작하여, 일본 국내는 물론 미국과 아시아 지역에서 높은 보급률을 가지고 있다. 특히 냉동공조용 열전달관 부분에 강한 면모를 보이고 있다. 여기서는 최근 개발된 열전달관에 관하여 그 개발 경위와 열전달특성에 관하여 소개하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.5
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• pp.523-530
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• 2013

In this work, we study a heat transfer enhancement technology using fan-shaped small-scale fins. Fins having a thickness of 10 ${\mu}m$ move up-down by a pulsating flow. Owing to these motions, the heat transfer on a surface increases dramatically. The two-way FSI (fluid-structure interaction) method was applied for the analysis, and the analysis model was evaluated using a single fin model by comparing the experimental results. In summary, a maximum 40% increase in heat transfer capacity using a single and multiple small-scale fins was obtained in comparison with the results obtained without using fins. From this work, we believe that the proposed method can be a promising method for heat transfer enhancement in real applications.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.10
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• pp.795-801
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• 2003

The primary object of this study is to obtain a basic knowledge of heat transfer enhancement mechanism as affected by temperature driven Marangoni convection. Experiments is achieved to visualize the enhanced heat transfer phenomena by the effect of Marangoni convection through the laser holographic interferometry. Also Nusselt Number is introduced for the relation of Marangoni Number.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.12
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• pp.1017-1024
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• 2006

In this work, pool boiling heat transfer coefficients (HTCs) of five hydrocarbon refrigerants of propylene, propane, isobutane, butane and dimethylether (DME) were measured at the liquid temperature of $7^{\circ}C$ on a 26 fpi low fin tube, Turbo-B, and Thermoexcel-E tubes. All data were taken from 80 to $10kW/m^2$ in the decreasing order of heat flux. The data of hydrocarbon refrigerants showed a typical trend that nucleate boiling HTCs obtained on enhanced tubes also increase with the vapor pressure. Fluids with lower reduced pressure such as DME, isobutane, and butane took more advantage of the heat transfer enhancement mechanism of enhanced tubes than those enhancement ratios of $2.3\sim9.4$ among the tubes tested due to its sub-channels and re-entrant cavities.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.716-723
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• 2016

Enhanced tubes are used widely in the heat exchangers of absorption chillers. In regenerators, corrugated, ribbed or floral tubes are commonly used. In this study, the tube-side heat transfer coefficients and friction factors of enhanced tubes were obtained experimentally using the Wilson Plot method. The results showed that the heat transfer coefficients and the friction factors were the largest for the corrugated tube, followed by the ribbed tube. The heat transfer coefficients and friction factors of the floral tube matched those of the smooth tube within 4%, which suggests that the heat transfer and friction characteristics of the floral tube may be accounted for properly by the hydraulic diameter. The B(e+) and g(e+) were obtained from the experimental data of the corrugated and ribbed tube. The B(e+) and g(e+) of the corrugated tube matched those of the existing correlation within 20%. The present results may be used for an assessment of the heat transfer and friction characteristics of the enhanced tubes for regenerators.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1447-1452
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• 2003

Vortex is very interesting flow phenomena on the heat transfer enhancement. In the present study, naphthalene sublimation technique is used to determine the average and local mass transfer coefficients on the flat plate with vortex generator. A parametric study with Reynolds number and angle of attack is carried out to investigate the heat transfer enhancement. The heat transfer coefficients on the flat plate with rectangular type and delta type vortex generator are compared with those of the flat plate without the vortex generator. Comparing heat transfer coefficients between rectangular type and delta type vortex generator, rectangular type vortex generator has much higher value than delta type vortex generator at the same condition.

• Journal of the KSME
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• v.43 no.3
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• pp.65-70
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• 2003

• Proceedings of the SAREK Conference
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• 2003.07a
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• pp.128-128
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• 2003

• Composites Research
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• v.26 no.6
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• pp.373-379
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• 2013

The coating of metal surface with carbon nanotubes (CNTs) has been studied for the heat transfer enhancement of the boiling and condensation of refrigerant. The MWCNT/copper composite powder was made by the attrition ball milling, which has been coated on the copper wafer by electrostatic powder coating and sintered with electric furnace. In this paper, experiments were performed to assess the characterization and comparison of CNT before and after sinterning and the morphology changes of the CNT/Cu-coated surface. The samples were examined by the scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDAX) and raman spectroscopy. To verify the heat transfer enhancement, boiling heat transfer tests were performed.