• Title/Summary/Keyword: Flush-Mounted Configuration

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The optimal array of various heat-generating heaters located on one wall of a vertical open top cavity (상부가 개방된 수직 캐비티내의 한쪽면에 배열된 다양한 발열조건을 갖는 발열체의 최적배열)

  • Riu, Kap-Jong;Choo, Hong-Lock;Choi, Byung-Cheol
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.1
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    • pp.15-23
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    • 1997
  • An experimental investigation of two-dimensional steady natural convection cooling in a vertical open top cavity with conducting side walls of finite thickness is presented. The various heat-generating discrete heaters are located on one vertical wall of the cavity. When each heater dissipates different amount of power, the purpose of the work is to obtain the optimal array condition of the heaters. The four cases of non-uniform heating conditions are considered. The temperature fields in the cavity were visualized by the interferometer and local temperatures of the vertical wall were measured by thermocouples. The heaters were arranged in two configurations: flush-mounted on a vertical wall or protruding from the wall about 4.5 mm. The vertical wall was constructed out of copper or epoxy-resin sheet. Experiments have been conducted for air with constant Prandtl number(Pr=0.7), the aspect ratio of 4.6, 7.5, 9.5, power input in the range of 0.9 W ~ 4.2 W. For the enhancement of the cooling effectiveness, the upper and lower of vertical wall would give the better position for the heaters of higher heat flux.

A Comparative Study of Frequency Response Models for Pressure Transmission System (압력전달시스템을 위한 주파수응답모델들의 비교 연구)

  • Kim, Hyeonjun;Choi, Hwan-Seok
    • Journal of the Korean Society of Propulsion Engineers
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    • v.24 no.2
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    • pp.83-93
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    • 2020
  • Dynamic pressure transducer needs to be flush-mounted on hardware due to frequency response characteristics of pressure transmission system. However, it is sometimes necessary to be mounted in recessed configuration due to insufficient space for sensor installation and for protection of sensor from thermal damage. Dynamic response characteristics should be considered due to distortion of original dynamic pressure signal in the pressure transmission system. In this study, small perturbation model and 2nd order reduced model were compared with experiments and a guideline for selecting a frequency response model was suggested.

Effect of Inlet Direction on the Refrigerant Distribution in an Aluminum Flat-Tube Heat Exchanger

  • Kim, Nae-Hyun;Kim, Do-Young;Byun, Ho-Won;Choi, Yong-Min
    • International Journal of Air-Conditioning and Refrigeration
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    • v.16 no.4
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    • pp.130-136
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    • 2008
  • The refrigerant R-134a flow distributions are experimentally studied for a round header/ten flat tube test section simulating a brazed aluminum heat exchanger. Three different inlet orientations(parallel, normal, vertical) were investigated. Tests were conducted with downward flow for the mass flux from 70 to 130 $kg/m^2s$ and quality from 0.2 to 0.6. In the test section, tubes were flush-mounted with no protrusion into the header. It is shown that normal and vertical inlet yielded approximately similar flow distribution. At high mass fluxes or high qualities, however, slightly better results were obtained for normal inlet configuration. The flow distribution was worst for the parallel inlet configuration. Possible explanation is provided based on flow visualization results.

Distribution of Air-Water Two-Phase Flow in a Header of Aluminum Flat Tube Evaporator (알루미늄 평판관 증발기 헤더 내 공기-물 2상류 분지 실험)

  • Kim Nae-Hyun;Shin Tae-Ryong;Sim Yong-Sup
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.1
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    • pp.55-65
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    • 2006
  • The air and water flow distribution are experimentally studied for a round header - flat tube geometry simulating a parallel flow heat exchanger. The number of branch flat tube is thirty. The effects of tube outlet direction, tube protrusion depth as well as mass flux, and quality are investigated. The flow at the header inlet is identified as annular. For the downward flow configuration, the water flow distribution is significantly affected by the tube protrusion depth. For flush-mounted configuration, most of the water flows through frontal part of the header. As the protrusion depth increases, more water is forced to the rear part of the header. The effect of mass flux or quality is qualitatively the same as that of the protrusion depth. Increase of the mass flux or quality forces the water to rear part of the header. For the upward flow configuration, however, most of the water flows through rear part of the header. The protrusion depth, mass flux, or quality does not significantly alter the flow pattern. Possible explanations are provided based on the flow visualization results. Negligible difference on the water flow distribution was observed between the parallel and the reverse flow configuration.

A Study on the Refrigerant Distribution in an Aluminum Parallel Flow Heat Exchanger Header (알루미늄 평행류 열교환기 헤더 내 냉매 분배에 관한 연구)

  • Kim, Do-Young;Kim, Nae-Hyun;Kim, Su-Hwan;Byun, Ho-Won;Lee, Eul-Jong
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.1123-1128
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    • 2009
  • The refrigerant R-134a flow distributions are experimentally studied for a round header/ten flat tube test section simulating a brazed aluminum heat exchanger. Three different inlet orientations (parallel, normal, vertical) were investigated. Tests were conducted with downward flow for the mass flux from 70 to $130\;kg/m^2s$ and quality from 0.2 to 0.6. In the test section, tubes were flush-mounted with no protrusion into the header. It is shown that normal and vertical inlet yielded approximately similar flow distribution. At high mass fluxes or high qualities, however, slightly better results were obtained for normal inlet configuration. The flow distribution was worst for the parallel inlet configuration. Possible explanation is provided based on flow visualization results.

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Distribution of Air-Water Two-Phase Flow in a Flat Tube Heat Exchanger (평판관 열교환기 내 공기-물 2상류 분지)

  • Kim, Nae-Hyun;Park, Tae-Gyun;Han, Sung-Pil;Shin, Tae-Ryong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.9
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    • pp.687-697
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    • 2006
  • The air and water flow distribution are experimentally studied for a heat exchanger composed of round headers and 10 flat tubes. The effects of tube protrusion depth as well as mass flux, and quality are investigated, and the results are compared with the previous 30 channel results. The flow at the header inlet is annular. For the downward flow configuration, the water flow distribution is significantly affected by the tube protrusion depth. For flush-mounted geometry, significant portion of the water flows through frontal part of the header. As the protrusion depth increases, more water is forced to the rear part of the header. The effect of mass flux or quality is qualitatively the same as that of the protrusion depth. Increase of the mass flux or quality forces the water to rear part of the header. For the upward flow configuration, different from the downward configuration, significant portion of the water flows through the rear part of the header. The effect of the protrusion depth is the same as that of the downward flow. As the protrusion depth increases, more water is forced to the rear part of the header. However, the effect of mass flux or quality is opposite to the downward flow case. As the mass flux or quality increases, more water flows through the frontal part of the header. Compared with the previous thirty channel configuration, the present ten channel configuration yields better flow distribution. Possible explanation is provided from the flow visualization results.