• Title/Summary/Keyword: Horizontal channel

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Convective Heat Transfer in a Channel with Isothermal Rectangular Beams (등온사각빔이 부착된 채널에서의 대류열전달)

  • Ree, J.S.;Kwon, S.S.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.7 no.1
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    • pp.63-72
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    • 1995
  • Convective heat transfer in a two-dimensional horizontal and vertical channel with isothermal rectangular beams attached to one adiabatic wall is investigated from the numerical solution of Navier-Stokes and energy equations. The solutions have been obtained for dimensionless beam spacings, S/L=1~4, aspect ratios of beam, H/B=0.25~4, Reynolds numbers, Re=50~1000 and Grashof numbers, $Gr=0{\sim}5{\times}10^4$. The total mean Nusselt number, Nu_T for horizontal and vertical channels shows same value at Gr=0. As Gr increases, Nu_T for horizontal channel increases, but Nu_T for vertical channel shows similar value at S/L=2, H/B=0.25, Re=100. The total mean Nusselt number for horizontal channel is higher than that for vertical channel. As H/B increases, $Nu_T$ for both channel decrease at $Gr=10^4$, Re=100.

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Heat Transfer Characteristics of Electronic Components in a Horizontal Channel According to Various Cooling Methods (다양한 냉각방법에 따른 수평채널 내 전자부품의 열전달 특성)

  • Son, Young-Seok;Shin, Jee-Young
    • Journal of Advanced Marine Engineering and Technology
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    • v.32 no.6
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    • pp.854-861
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    • 2008
  • Heat transfer characteristics of protruding electronic components in a horizontal channel are studied numerically. The system consists of two horizontal channels formed by two covers and one printed circuit board which has three uniform protruding heat source blocks. A two-dimensional numerical model has been developed to predict the conjugate heat transfer. and the finite volume method is used to solve the problem. Five different cooling methods are considered to examine the heat transfer characteristics of electronic components according to the different cooling methods. The velocity and temperature of cooling medium and the temperature of the heat source blocks are obtained. The results of the five different cooling methods are compared to find out the most efficient cooling method in a given geometry and heat sources.

Reflood Experiments with Horizontal and Vertical Flow Channels

  • Chung, Moon-Ki;Lee, Seung-Hyuck;Park, Choon-Kyung;Lee, Young-Whan
    • Nuclear Engineering and Technology
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    • v.12 no.3
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    • pp.153-162
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    • 1980
  • The investigation of the fuel cladding temperature behavior and heat transfer mechanism during the reflooding phase of a LOCA plays an important role in performance evaluation of ECCS and safety analysis of water reactors. Reflooding experiments were performed with horizontal and vertical flow channels to investigate the effect of coolant flow channel orientation on rewetting process. Emphasis was mainly placed on the CANDU reactor which has horizontal pressure tubes in core, and the results were compared with those of vertical channel. Also to investigate the rewetting process visually, the experiments by using a rod in annulus and a quartz tube heated outside were performed. It can be concluded that the rewetting velocity in horizontal flow channel is clearly affected by flow stratification, however, the average rewetting velocity is similar to those in vertical flow channel for same conditions.

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The Study about Cooling Effect of a Heated module in a Horizontal Channel with a Variation of Channel Height (수평채널 밑면에 부착된 단일 발열모듈에서 채널높이의 변화에 따른 냉각특성 연구)

  • 이진호;유갑종;장준영;김병하
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.5
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    • pp.348-355
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    • 2001
  • The coupled conduction and convection heat transfer from a protruding heated module in a horizontal channel with a variation of channel height is experimentally investigated. The input power to the module is 3, 7W and thermal resistance of module support is 0.06 , 1.03 and 158K/W. the Reynolds number ranged from 350 to 4500 corresponding to the inlet velocity(0.4~1.3 m/s) and channel height(11~35 mm). The results were obtained that the decrease of thermal resistance of module support reduces the module temperature by redistributing the heat flux and the overall thermal resistance of the module. In the study the effect of channel height is very significant in the adiabatic condition, but negligible in the conjugate condition. Finally, correlations for Nusselt number and $Q_B$/Q with a variation of Reynolds number were developed respectively.

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Horizontal Distance Correction of Single Channel Marine Seismic Data (단일 채널 해양 탄성파탐사 자료의 수평거리 보정)

  • Kim Hyun-Do;Kim Jin-Hoo
    • Geophysics and Geophysical Exploration
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    • v.7 no.4
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    • pp.245-250
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    • 2004
  • Horizontal-axes on the seismic section have been represented in a distance unit by applying horizontal-distance correction transformation on a 2-D seismic section of single channel marine seismic data. By drawing horizontal-axes in a distance unit, distortion of horizontal distances shown on the seismic section when the ship speed varies during a survey can be diminished considerably. Position information obtained by GPS and stored in each trace of seismic data as well as data collection windows were used for horizontal distance correction. The minimum window length was decided by considering ship speed and shot interval, and the maximum window length wat determined by reflecting radius of the 1st Fresnel zone. In choosing an optimum window length, horizontal resolution and stacking effect were considered simultaneously. By applying horizontal distance correction we could get a 2-D seismic section which is considered at reflecting the real subsurface structure analogously.

The Effect of Header and Channel Angle Variation on Two-Phase Flow Distribution at Multiple Junctions (헤더-채널 분기관의 각도변화가 2상 유동 분배에 미치는 영향에 대한 연구)

  • Lee, Jun Kyoung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.11
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    • pp.559-566
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    • 2015
  • The main objective of this work is to experimentally investigate the effect of angle variation on the distribution of two-phase flow at header-channel junctions. The cross-sections of the header and the channels were fixed at $16mm{\times}16mm$ and $12mm{\times}1.8mm$, respectively. Air and water were used as the test fluids. Four different header-channel positions were tested : Vertical header with Horizontal channels (case VM-HC), Horizontal header with Horizontal channels (case HM-HC), Horizontal header with Vertical Downward channels (case HM-VDC), and Horizontal header with Vertical Upward channels (case HM-VUC). In all cases, liquid flow distribution tended to decrease gradually in the upstream header region. However, in the downstream region, different trends could be seen. The reason for these different tendencies were identified by flow visualization in each case. The standard deviations for the liquid and gas flow distribution in each case were calculated, and the case of VM-HC had the lowest values compared to other cases because of the symmetrically distributed liquid film and strong flow recirculation near the end plate.

3-D Numerical Analysis on a low Reynolds Number Mixed Convection in a Horizontal Rectangular Channel (수평 사각채널 내 저 레놀즈수 혼합대류 유동의 3차원 수치해석)

  • Piao, Ri-Long;Bae, Dae-Seok
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2005.06a
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    • pp.210-215
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    • 2005
  • A three-dimensional numerical simulation is performed to investigate on a low Reynolds number mixed convection in a horizontal rectangular channel with the upper part cooled and the lower part heated uniformly. The three-dimensional governing equations are solved using a finite volume method. For convective term, the central differencing scheme is used and for the pressure correction, the PISO algorithm is used. Solutions are obtained for A=4, Pr=0.72, 10, 909, the Reynolds number ranging from $2.1{\times}10^{-2}$ to $1.2{\times}10^{-1}$, the Rayleigh number is $3.5{\times}10^4$. It is found that vortex roll structures of mixed convection in horizontal rectangular channel can be classified into three roll structures which affected by Prandtl number and Reynolds number.

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Study on Effect of Channel Intrusion Depth on the Two-Phase Flow Distribution at Header-Channel Junction (헤더-채널 분기관의 채널 돌출길이가 2상 유동 분배에 미치는 영향에 대한 연구)

  • Lee, Jun Koung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.28 no.11
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    • pp.444-449
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    • 2016
  • The main objective of this work is to experimentally investigate the effect of angle variation and intrusion depth of channels on the distribution of two-phase flow at header-channel junctions. The dimensions of the header and the channels in cross-section were fixed at $16mm{\times}16mm$ and $12mm{\times}1.8mm$, respectively. Air and water were used as the test fluids. Two different header-channel positions were tested : a vertical header with horizontal channels (case VM-HC) and a horizontal header with horizontal channels (case HM-HC). In all cases, the intrusion depths of the channels are 0 mm, 2 mm, and 4 mm. For the case of the intrusion depth of VM-HC, the flow distribution became more uniform. However, the intrusion depth negatively affected the flow distribution for the case of HM-HC because liquid separation delay occurred.

An Experimental Study on Pressure Drop of Boiling Flow within Horizontal Rectangular Channels with Small Heights (미세 수평 사각 유로 내에서의 비등 유동 압력강하에 관한 실험적 연구)

  • Lee, Sang-Yong;Lee, Han-Ju
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.9
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    • pp.1219-1226
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    • 2001
  • Pressure drops were measured for the flow boiling process within horizontal rectangular channels. The gap between the upper and the lower plates of each channel ranges from 0.4 to 2mm while the channel width being fixed to 20mm. Refrigerant 113 was used as the test fluid. The mass flux ranges from 50 to 200kg/㎡s and the channel walls were uniformly heated up to 15kW/㎡. The quality range covers from 0.15 to 0.75. The present experimental conditions coincide with the operating conditions of compact heat exchangers in which the liquid and gas flows are laminar and turbulent. The measured results were well represented by the two-phase frictional multiplier of Lee (2001) which has been developed for air-water two-phase flows within the deviation of $\pm$20%.

Performance Test for a Horizontal Regenerative Evaporative Cooler (수평형 재생증발식 냉방기의 성능시험)

  • Song, Gwi-Eun;Lee, Dae-Young
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.621-626
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    • 2006
  • Regenerative evaporative cooling is known as an environment-friendly and energy efficient cooling method. A regenerative evaporative cooler (REC) consisting of dry and wet channels is able to cool down the air stream below the inlet wet-bulb temperature. In the regenerative evaporative cooler, the cooling effect is achieved by redirecting a portion of the air flown out of the dry channel into the wet channel and spraying water onto the redirected air. In this study, a horizontal regenerative cooler is considered. In the horizontal regenerative cooler, the flow direction of evaporating water has a right angle to the flow direction of supply air. This difference was investigated with visualization technique and simplified 2-module performance test was done in a thermo-environment chamber. Optimum design configuration is changed due to the wet channel which are easily fully covered with evaporating water and block the air flow inside the channel. Applying the optimized fin configuration design with the highly wetting surface treatment, a regenerative evaporative cooler was fabricated and tested to Identify the cooling performance improvement and operation characteristics. From the experimental results at the intake condition of $32^{\circ}C$ and 50% RH, the supply temperature was measured to be around $23.4^{\circ}C$. The cooling effectiveness based on the inlet dewpoint temperature was evaluated 73% which is almost close to the design expectation.

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