• Title/Summary/Keyword: 휜

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Heat Transfer Optimization in a Tube with Circular-Sectored Fins (원관내 부채꼴 휜 주위에서의 열전달 최적화)

  • Yoo, Jae-Wook;Kim, Sung-Jin;Hyun, Jae-Min
    • Proceedings of the KSME Conference
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    • 2000.04b
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    • pp.57-64
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    • 2000
  • The present work investigates the heat transfer characteristics for laminar fully developed forced convection in an internally finned tube with axially uniform heat flux and peripherally uniform temperature through analytical models of convection in a porous medium. Using the Brinkman-extended Darcy flow model and the two equation model fur heat transfer, analytical solutions fur fluid flow and heat transfer are obtained and compared with the exact solution for fluid flow and the numerical solutions for conjugate heat transfer to validate the porous medium approach. Using the analytical solutions, parameters of engineering importance are identified and their effects on fluid flow and heat transfer are studied. Also, the expression fur total thermal resistance is derived from the analytical solutions and minimized in order to optimize the thermal performance of the internally finned tubes.

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Experimental Study on Spray Cooling Heat Transfer of Micro-Fins Surfaces (마이크로 휜 표면의 분무냉각 열전달에 관한 실험적 연구)

  • Kim, Yeung-Chan
    • Journal of ILASS-Korea
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    • v.14 no.4
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    • pp.178-183
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    • 2009
  • Spray cooling heat transfer was experimentally investigated for water sprays impacting on mico-fins structured surfaces in the single phase and nucleate boiling regions. The heat transfer surfaces consist of cubic fins and triangular grooved fins. The spray produced using full cone spray nozzles, and experiments were made under the test condition of $Q=4.92{\times}10^{-6}{\sim}15.83{\times}10^{-6}\;m^3/s$, $T_f=35{\sim}55^{\circ}C$. From the experimental results, it was found that cubic fins surface had the largest heat flux enhancement relative to the smooth surface.

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Flow and Heat Transfer Characteristics due to Staggered Arrangement of Heat Pipes in Channels with Heat Pipes and Fins (휜-히트파이프로 구성된 채널에서 히트파이프의 엇갈림배열에 따른 유동 및 열전달 특성)

  • 김성훈;진윤근;김철주
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.11
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    • pp.871-879
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    • 2002
  • The characteristics of flow and heat transfer in the heat exchanger of heat pipes with fins have been studied numerically for cooling enhancement of electronic components of KTX (Korea Train eXpress). Numerical analysis and methodology have been conformed by comparing the experimental results for inlined array of heat pipes. The staggered arrangement of heat pipes has been proposed in order to achieve heat transfer enhancement. As results, the geometry change to the staggered array is conformed to increase the heat transfer of the system accompanied by an increase of pressure drop. The current results of friction factor and Colburn j factor are presented in terms of Reynolds number and staggered distance, and are expected to use for design and manufacture of such a system.

Cooling Characteristics of a Strip Fin Heat Sink (스트립휜 히트싱크의 냉각특성)

  • Park. Cheol-Woo;Kim. Hyun-Woo;Jang .Chung-Sun;Riu. Kap-Jong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.1 s.232
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    • pp.16-26
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    • 2005
  • Air-cooled heat sinks are employed in many electronic cooling applications since they provide significant heat transfer enhancement and operational flexibility. Strip-shaped fin heat sink is of interest and needs to be investigated as general cooling products for more applicability. The purposes of this study are to evaluate heat sink performance without bypass flow condition and to determine optimal heat sink geometries. The results show that the decreasing rate of thermal resistance of a heat sink decreases with increasing inlet air velocity, and the increasing rate of pressure drop increases with increasing inlet air velocity, but is not affected by input power. The increasing rate of optimal longitudinal fin spacing is larger than that of transverse fin spacing. The strip fin heat sink tested in this study showed better cooling performance compared to that of other plate fin type.matism. 2004; 50(11): 3504-3515.

Forced Convection Characteristics of V shape Circular fin-tube Heat Exchanger (V형 원형휜-원형관의 강제대류 열유동 특성)

  • Lee, Jong-Hwi;Lim, Moo-Gi;Kang, Hie-Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.21 no.12
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    • pp.649-655
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    • 2009
  • The purpose of the present study is to investigate the flow resistances and heat transfer characteristics of V-shaped circular fin-tube heat exchangers. Four types of V-shaped fins in which the fin areas are identical but the areas of the V-shaped portion are different have been tested numerically. The results obtained for heat transfer, pressure drop, and fin temperature are discussed in this paper. With increase in the area of the V-shaped portion, the pressure drop and heat transfer increase up to 40% and 24%, respectively, in the present test range.

Design of Annular Finned Heat Transfer Tube Using Robust Optimization (원형 확장 휜 열 교환기의 치수 강건최적설계)

  • Jhong, Woo-Jin;Yoon, Ji-Won;Lee, Jong-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.9
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    • pp.1437-1443
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    • 2003
  • Most optimization problems do not consider tolerance of design variables and design parameters. Ignorance of these tolerances may not fit for the practical problems and can lead to an unexpected conclusion. That is why we suggest robust optimization considering tolerances in both design variables and problem parameters. Using robust optimization, we designed minimum weight annular finned heat transfer tube subject to constraints on limitation of pressure difference and minimum value of total heat transfer. Consequently, robust optimization satisfies tolerance considered practical problems.

Experimental Study on the Effect of Tip Clearance for a Straight Fin Heat Sink (팁 클리어런스가 스트레이트 휜 히트싱크의 냉각성능에 미치는 영향에 관한 실험적 연구)

  • Kim, Jin-Wook;Kim, Sung-Jin;Min, Jung-Im;Lee, Seung-Gyu
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1189-1194
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    • 2004
  • In this paper, the effect of tip clearance on the cooling performance of the microchannel heat sink is presented under the fixed pumping power condition. For the various types of microchannel heat sink having different size of fin width and channel width, experimental study is conducted. Through the experiment, the tip clearance effect is investigated by increasing tip clearance from zero. As a result, it is shown that cooling performance of heat sink with tip clearance is better than that of heat sink without tip clearance. For the microchannel heat sink with tip clearance, the optimum conditions for cooling performance is also studied.

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Performance Evaluation of a Fin-Tube Heat Exchanger Using One-Dimensionalized Refrigerant Circuit (냉매유로를 1차원 배열화한 휜-관 열교환기 성능해석)

  • Kim, Doo-Hwan;Ye, Huee-Youl;Lee, Kwan-Soo;Cha, Woo-Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.20 no.12
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    • pp.833-843
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    • 2008
  • A new method is presented for developing a simulation program which can analyze the heat transfer characteristics of fin-tube heat exchanger. This method is able to describe several types of refrigerant circuit arrangement. The delivery path of air and refrigerant properties is simplified by transforming three-dimensional array into one-dimensional array. By comparing simulated results with experiment results, the deviation was 8.2%. Several fin-tube heat exchangers of different design factors and operating conditions were simulated using this program. It was shown that this program could be used for designing practical fin-tube heat exchangers.

Free Convection Correlation for the Single Circular Finned Tube Heat Exchanger (단일 원형관-원형휜 열교환기의 자연대류 열전달 실험관계식)

  • Kang, Hie-Chan;Jang, Hyun-Soon;Hong, Cha-Kun
    • Proceedings of the SAREK Conference
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    • 2008.11a
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    • pp.596-600
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    • 2008
  • An experimental study has been conducted on the free convection heat transfer for the 7 kinds of circular finned tube heat exchangers. Empirical correlation was suggested at the range of 3,500$D_o$/$D_i$<3.0, 0.19<$P_f$/$D_i$<0.34. The 92% of experimental data agreed with the correlation within 10%.

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Numerical study for the fin efficiency of the heat exchanger having plate fins (판형 휜을 갖는 열교환기의 휜효율에 관한 수치해석적 연구)

  • 강희찬
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.11 no.6
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    • pp.903-911
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    • 1999
  • This study is discussed about the heat transfer coefficient and the fin efficiency of the heat exchanger having plate fins. A new definition for the fin efficiency of the heat exchanger is proposed. More than one hundred cases were tested numerically for the plate fins having uniform and non-uniform heat transfer coefficient. The previous models for the fin efficiency and the pure heat transfer coefficient were applicable to the heat exchanger only when the NTU is very small. It was found that the fin efficiency of the heat exchanger was nearly the same as the normalized fin temperature. The present model could estimate the pure heat transfer coefficient within a few percent in the present test range of 0<NTU<2.5.

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