• Title/Summary/Keyword: Triangular Duct

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Effects of Wavy Tapers on Heat Transfer in the Reciprocating Rectangular Channel (왕복운동을 하는 사각채널에서 파형테이퍼가 열전달에 미치는 효과)

  • 안수환;배성택
    • Journal of Advanced Marine Engineering and Technology
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    • v.27 no.5
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    • pp.600-608
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    • 2003
  • This Paper describes a detailed experimental investigation of heat transfer in a reciprocating smooth rectangular duct having only the bottom wall heated with reference to the design of a piston for a marine propulsive diesel engine The Parametric test matrix involves Reynolds number and reciprocating radius, respectively, in the range of 1.280∼4.100, and 7∼15 cm with five different reciprocating frequency tested. namely. 1.7, 2.2, and 2.6 Hz. The effects of three different hemi-triangular wavy type tapers on the heat transfer in the reciprocating rectangular channel using the air as a working fluid were check out. The present work confirms that the Nusselt number in the channel with the triangular wavy type taper is lower than without the triangular wavy type taper.

Heat Transfer and Pressure Drop Characteristics of Triangular Ducts with One Side Rib-Roughened (한 측에서만 거칠기가 설치된 삼각덕트의 마찰계수와 열전달)

  • 안수환;이영석
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.2
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    • pp.17-23
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    • 2000
  • Experimental investigations were conducted to study the forced convection of fully-developed turbulent flow in horizontal equilateral duct fabricated with the same length and equivalent diameter, but different surface roughness pitch ratio(P/e) of 4, 8 and 16 on the one side wall only. The experiments were performed with the hydraulic diameter based Reynolds number ranged from 70,000 to 10,000. The entire bottom wall of the duct was heated uniformly and the other surfaces were thermally insulated. To understand the mechanisms of the heat transfer enhancement, measurements of the heat transfer were done to investigate the contributive factor of heat transfer promotion, namely, the fin effect. And the results were compared with those of previous investigations for similarly configured channels, at which they were roughened by regularly spaced transverse ribs in the rectangular and circular channels.

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Heat Transfer and Pressure Drop Characteristics of Triangular Ducts with One Side Rib-Roughened (한 측에서만 거칠기가 설치된 삼각덕트의 열전달과 압력강하 특성)

  • Ahn, S.W.;Lee, Y.S.;Lee, B.C.
    • Proceedings of the KSME Conference
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    • 2000.04b
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    • pp.65-70
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    • 2000
  • Experimental investigations were conducted to study the forced convection of fully-developed turbulent f)on· in horizontal equilateral duct fabricated with the same length and equivalent diameter, but different surface roughness Pitch ratio(P/e) of 4, 8 and 16 on the one side wall only The experiments were performed with the hydraulic diameter based Reynolds number ranged from 70.000 to 10,000 The entire bottom wall of the duct was heated uniformly and the other surfaces were thermally insulated. To understand the mechanisms of the heat transfer enhancement. measurements of the heat transfer were done to investigate the contributive factor of heat transfer promotion. namely the fin effect. And the results were compared with those of Previous investigations for similarly configured channels, at which they were roughened by regularly spaced transverse ribs in the rectangular and circular channels.

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Effects of Rib Cross Section Shapes on Heat Transfer of a Rib-Roughened Duct (터빈 기익 내부관 열전달 증대를 위해 설치된 요철의 형상 효과)

  • Wu, Seong Je;Kwon, Hyuk Jin;Cho, Hyung Hee
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.1
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    • pp.149-157
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    • 1999
  • Heat transfer in a duct is augmented remarkably by rib turbulators. However, increasing friction loss is accompanied due to ribs disturbing flows. Hence, pressure drops and heat transfer are considered simultaneously to decide heat/mass transfer performance in a rib-roughened duct. In the present study, the effects of rib cross section shape on pressure drop through a duct are investigated as well as those on heat transfer characteristics. The results show that the characteristics of heat/mass transfer and friction loss in the duct roughened with triangular ribs are similar to those with square ribs, while significantly different from those with semicircular ribs. The best performance in the duct is obtained by using semicircular shaped ribs among three types of ribs for the large rib angles of ${\alpha}{\geq}63^{\circ}$.

A Study on Heat Transfer Enhancement for a Shear-Thinning Fluid in Triangular Ducts (삼각형 단면 덕트 내의 Shear-Thinning 유체에 대한 열전달 촉진에 관한 연구)

  • Lee, Dong-Ryul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.9
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    • pp.3808-3814
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    • 2011
  • The prediction of heat transfer and pressure drops in the exchanger passages is a clue to the problem of heat exchanger design. In order to make such predictions for non-Newtonian fluids, it is necessary to know the relation between the viscous properties of the fluid and the wall shear rate in the duct. This study deals with the limits of validity of the power law equation. The useful methodology of the present research involves a consideration of a more general equation which has power law and Newtonian behavior as asymptotes. It isconcluded that use of the power law equation outside of its applicability range can lead to serious errors inpredicting the heat transfer and pressure drops. The present computational results of the friction factors times Reynolds number for shear-thinning fluid flows in a triangular duct are compared with previous published results, showing agreement with 0.13 % in Newtonian region and 2.85 % in power law region. These shear-thinning fluid results also showed the 12% increase of convective heat transfer enhancement compared with Newtonian heat transfer.

Friction Factor and Heat Transfer in Equilateral Triangular Ducts with Surface Roughness

  • Ahn, Soo-Whan
    • Journal of Mechanical Science and Technology
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    • v.15 no.5
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    • pp.639-645
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    • 2001
  • Experimental investigations were conducted to study forced convection of fully developed turbulent flows in horizontal equilateral triangular ducts with different surface roughness pitch ratios (P/e) of 4, 8, and 16 on one side. The ducts bottom wall was heated uniformly and the other surfaces were thermally insulated. To understand heat transfer enhancement mechanism, heat transfer rates were measured. Smooth triangular ducts were also tested for benchmark purposes. The results were compared with previous results for similarly configured channels, at which they were roughened by regularly spaced transverse ribs in the rectangular and circular channels.

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'Triangular Cord' Sign in Biliary Atresia (담도폐쇄증에서 'Triangular Cord' Sign)

  • Hee Jung Lee;Mu Sook Lee;Jin Young Kim
    • Journal of the Korean Society of Radiology
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    • v.83 no.5
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    • pp.1003-1013
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    • 2022
  • Biliary atresia is an unknown etiology of extrahepatic bile duct obstruction with a 'fibrous ductal remnant,' which represents the obliterated ductal remnant in the porta hepatis. The sonographic 'triangular cord' (TC) sign has been reported to indicate a fibrous ductal remnant in the porta hepatis. In this review, we discuss the correlations among surgicopathological and sonographic findings of the porta hepatis and the definition, objective criteria, diagnostic accuracy, and differential diagnosis of the TC sign in biliary atresia.

The Effects of Tube Arrangement and Inclination on the Pressure Drop in Tube Bundles of Intermediate Beat Exchanger in Liquid Meta Reactor (액체금속로 중간열교환기 관다발에서의 튜브배열과 경사각도가 압력강하에 미치는 영향)

  • Nam Ho Yun;Kim Jong Man;Choi Jong Hyeun
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.659-662
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    • 2002
  • The present paper presents the experimental results for pressure drop in inclined tube bundles located in a rectangular duct. Measurements are made for pressure drop in triangular and rotated triangular tube arrays having P/d ratio of 1.6 and inclination angles of 30,45,60 and 90 degrees. The Reynolds number based on the free stream velocity and tube diameter ranges from $8{\times}10^2\;to\;6.3{\times}10^{4}$. The experimental results show that the magnitude of dimensionless pressure drop decreases significantly when the inclined angle is less than 45 degree. The measured data are compared with two existing correlations available in the literatures. The ESDU correlation agrees well with the present data far the triangular arrays. But some discrepancies are observed for the rotated triangular arrays when the inclined angles are 30 and 45 degrees. The Idel'chik correlation generally agrees well with the measured data for the rotated triangular arrays except for the inclined angle of 30 degree. The Idel'chik correlation needs modification for the triangular arrays. The modified Idel'chik correlation agrees well with the measured data within $10{\%}$. It is found that the present measured data can be applied to the evaluation and modification of previous correlations.

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An Investigation on Friction Factors and Heat Transfer Coefficients in a Rectangular Duct with Surface Roughness

  • Ahn, Soo-Whan;Son, Kang-Pil
    • Journal of Mechanical Science and Technology
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    • v.16 no.4
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    • pp.549-556
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    • 2002
  • An investigation on the fully developed heat transfer and friction factor characteristics has been made in rectangular ducts with one-side roughened by five different shapes. The effects of rib shape geometries as well as Reynolds numbers are examined. The rib height-to-duct hydraulic diameter, pitch-to-height ratio, and aspect ratio of channel width to height are fixed at e/De=0.0476, P/e=8, and W/H=2.33, respectively. To understand the characteristics of heat transfer enhancements, the friction factors are also measured. The data indicates that the triangular type rib has a substantially higher heat transfer performance than any other ones.

Effects of Rib Shapes on the Friction Factors and Heat Transfer in a Rectangular Duct (사각 덕트에서 거칠기 형상이 마찰계수와 열전달에 미치는 효과)

  • 안수환;손강필
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.5
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    • pp.341-347
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    • 2001
  • A comparison of fully developed heat transfer and friction factor characteristics has been made in rectangular ducts with ones roughened by five different shapes. The effects of rib shape geometries and Reynolds number are examined. The rib height-to-duct hydraulic diameter, pitch-to height ratio, and aspect ratio of channel width to height are fixed at $e$/De=0.0476, P/$e$=8, and W/H=2.33, respectively. To understand the mechanisms of the heat transfer enhancements, the measurements of the friction factors are also conducted in the smooth and rough channels. The data indicates that the triangular type rib has a substantially higher heat transfer performance than any other ones in the range we studied.

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