• Title/Summary/Keyword: Oval-tube

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Heat Transfer Characteristics of Oval-Tube Heat Exchanger (타원관 열교환기의 열전달 특성)

  • 윤점열;이욱용
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.12 no.3
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    • pp.292-301
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    • 2000
  • This study experimentally investigates an air-side performance of oval tube heat exchanger against round tube heat exchanger using scaled-up model experiment for home air conditioners. A plain fin and round tube heat exchanger with 21 FPI(fins per inch) was used as a reference heat exchanger, and these were applied equally to 4 oval tube heat exchangers. Oval tube samples were designed with the same perimeter as 7.5mm diameter round tube, and their aspect ratios were 1:2, 1:3, respectively. In this study, the heat transfer and pressure drop characteristics of oval tube heat exchangers against round tube heat exchanger were also compared to one another, and an optimal samples for home air conditioners was recommended. And, general performance characteristics for an optimum oval tube samples chosen in this work was compared with round tube heat exchanger.

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Local Heat Transfer Characteristics on Fin Surface of Plate Fin - Oval Tube with Delta Wing Vortex Generators (Plate fin-oval tube 열교환기에서 와류발생체에 의한 fin 표면에서의 국소 열전달 특성)

  • Shin, Seok-Won;Chung, In-Kee;Kim, Soo-Youn
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2390-2395
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    • 2007
  • The present research was experimentally performed to analyze the effect of delta-wing vortex generators(DWVG) on the heat transfer of fin surface of the plate fin-oval tube. The local heat transfer coefficient of the fin surface for four kinds of DWVG's arrangement was measured by the naphthalene sublimation technique for Reynolds numbers ranging from 2000 to 3200. The results showed that the heat transfer of the plate fin-oval tube can be significantly enhanced by DWVG for relatively low Reynolds numbers.

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Wet Surface Air-Side Performance of Fin-and-Tube Heat Exchangers Having Sine Wave Fins and Oval Tubes (사인 웨이브 핀과 타원관으로 구성된 핀-관 열교환기의 공기측 습표면 성능)

  • Kim, Nae-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.4
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    • pp.2415-2423
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    • 2015
  • Experiments were conducted on sine wave fin-and-tube heat exchangers having oval tubes under wet condition. Oval tubes having an aspect ratio of 0.6 were made, by deforming 12.7mm round tubes. Twelve samples, having different fin pitch and tube row, were tested. Results showed that, for oval tube samples, the effect of fin pitch on j and f factor was not significant. As for the effect of tube row, the lowest j factor was obtained for one row configuration(81% of two row configuration), which is clear contrast to round tube samples, where the highest j factor was obtained for one row configuration. Possible reasoning is provided considering the flow and heat transfer characteristics of sine wave channel combined with connecting oval tubes. Comparison of $j/f^{1/3}$ with plain fin-and-tube heat exchanger having 15.9mm O.D. round tube reveals that present oval fin-and-tube heat exchanger shows superior thermal performance except for one row configuration. In other words, $j/f^{1/3}$ of the two row oval tube heat exchanger was 1.6~2.5 times larger than those of round tube heat exchanger, 1.4~2.4 times larger for three row configuration and 1.2~2.8 times for four row configuration.

The Numerical Analysis of the Flow Fields near Fin Surface of a Plate Fin-Oval Tube Heat Exchanger with Delta Wing Vortex Generators (Delta Wing Vortex Generator가 부착된 Plate Fin-Oval Tube 열교환기에서 휜 주위의 유동에 대한 수치적 해석)

  • Shin, Seok-Won;Chung, In-Kee;Kim, Soo-Youn;Lee, Young-Woo
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.2023-2028
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    • 2008
  • In present study, the flow field near the fin surface of plate fin - oval tube heat exchanger with delta wing vortex generator was numerically analyzed. As results, the well developed vortex behind delta wing was observed. These vortex can improve heat transfer fin surface behind delta wing vortex generators.

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Air-Side Performance of Fin-and-Tube Heat Exchangers Having Sine Wave Fins and Oval Tubes (사인 웨이브 핀과 타원관으로 구성된 핀-관 열교환기의 공기측 성능)

  • Choi, Byung-Nam;Yi, Fung;Sim, Hyun-Min;Kim, Nae-Hyun
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.25 no.5
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    • pp.279-288
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    • 2013
  • Heat transfer and pressure drop characteristics of fin-and-tube heat exchangers having sine wave fins and oval tubes were investigated. Oval tubes having an aspect ratio of 0.6 were made, by deforming 12.7 mm round tubes. Twelve samples, having different fin pitch and tube row, were tested. The effect of fin pitch on the j and f factors was negligible. The effect of the tube row on the j factor, however, was different from that of common fin-and-tube heat exchangers having plain fins and round tubes. The highest j factor was obtained for a two-row configuration, while the lowest one was obtained for a one-row configuration. A possible reason was attributed to the flow mixing characteristics of the sine wave channel of the present geometry. Comparison with a plain fin-and-tube heat exchanger having 15.88 mm O. D. round tube reveals that the present oval fin-and-tube heat exchanger shows generally superior thermal performance, except for the one-row configuration.

Finite Element Bending Analysis of Oval Tubes Using Rotary Draw Bender for Hydroforming Applications (로터리 드로우 벤더를 이용한 타원형 튜브의 유한요소 벤딩 해석)

  • Lee Ho-Kuk;Tyne Chester J. Van
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.10a
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    • pp.71-74
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    • 2005
  • In manufacturing automotive parts, such as engine cradles, frame rails, subframes, cross-members, and other parts from circular tubes, pre-bending and pre-forming operations are often required prior to the subsequent tubular hydroforming process. During some pre-forming operations, the cross section of a bent circular tube is crushed into an oval-like shape to ensure proper geometry and sufficient clearance in the hydroforming dies. For such applications, the use of oval Instead of circular tubes could be an effective means of eliminating the pre-forming step. The oval tube could also be produced with less thinning and with less strain on the outside of the bend when controlled by a booster system without the use of mandrel. Hence, the understanding of the issues that occur in the bending of oval tubes is worthy of Investigation. This paper presents parametric studies on the bending of oval tubes without a mandrel. The finite element modeling technique is used to examine the deformation characteristics for both circular and oval tubes. In the simulations, the bending process parameters of bend radius, aspect ratio of the tube ovalness, and tube wall thickness are varied. Observations are made to obtain a hoop-buckle limit diagram in terms of a non-dimensional shape degradation factor. Suggestions based upon developed criteria are made on the acceptability of bend tubes suitable for hydroforming applications without the need ofa pre-forming step or the used of a mandrel.

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Ice Making Characteristics according to Shape and Diameter on Ice-on-Coil Tube (관외착빙형 제빙관의 형태 및 관경 변화에 따른 제빙 특성)

  • Park, K.W.;Jeong, E.H.;Hwang, S.S.
    • Journal of Power System Engineering
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    • v.16 no.5
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    • pp.32-39
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    • 2012
  • The study experimented to understand ice-on-coil type ice making characteristics on to 3 kinds of circular tube, oval tube and small diameter tube using ice maker. The experiment were carried out under various conditions, that used brine temperature($-10^{\circ}C$, $-6^{\circ}C$), brine flow rate(1.0m/s, 1.8m/s) and inlet water temperature ($6^{\circ}C$, $12^{\circ}C$) etc. Mass of ice per ice making area increased according to the decrease of the brine temperature and inlet water temperature, but that was increased according to the increase of the brine flow rate. Oval ice making tube produced ice 1.11 to 2.46 times that of 9mm circular ice making tube, and 3mm small diameter ice making tube produced ice 1.06 to 1.51 times that of 9mm circular ice making tube.

Performance Characteristics of Fin-Tube Heat Exchanger having Large Diameter Oval Tube for Dryer (대구경 타원관을 적용한 건조기용 핀-관 열교환기의 성능특성)

  • Bae, Kyung-Jin;Cha, Dong-An;Kwon, Oh-Kyung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.1
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    • pp.8-13
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    • 2015
  • The objective of this paper is to provide design data of fin-tube heat exchanger which have a large diameter oval tube for dryer application. In this study, the heat transfer and pressure drop performance characteristics of the fin-tube heat exchanger were compared with Dittus-Boelter and a new correlation equation using Wilson plot method. The simulation results based on section by section method were compared with experimental results. These results showed that a new correlation equation using Wilson plot method provided better prediction, about 3 to 12%, than the Dittus-Boelter equation, from the experiment comparison. Also, the pressure drop of simulation results showed much more deviation with the experimental results.

CONVECTIVE HEAT TRANSFER CHARACTERISTICS OF OVAL FIN-CIRCULAR TUBE HEAT EXCHANGER (타원형휜-원형관 열교환기의 강제대류 열전달 특성)

  • Kang, H.C.;Lee, J.H.
    • Journal of computational fluids engineering
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    • v.15 no.2
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    • pp.1-6
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    • 2010
  • The purpose of the present study is to investigate the flow resistance and the heat transfer characteristics of oval fin-tube heat exchanger. Six kinds of oval fin having the same fin area and different diameter ratio tested numerically. Test data for the heat transfer, pressure drop and fin temperature were shown and discussed. The pressure drop and heat transfer increased for increasing the oval fin diameter ratio(diameter of span-wise direction to diameter of longitudinal diameter) up to 50% and 45% respectively.