대한기계학회논문집B (Transactions of the Korean Society of Mechanical Engineers B)

  • 제35권7호
  • /
  • Pages.701-708
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  • 2011
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  • 1226-4881(pISSN)
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  • 2288-5324(eISSN)
대한기계학회 (The Korean Society of Mechanical Engineers)
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경사진 평판에서의 자연대류 열전달

Natural Convection Heat Transfer on Inclined Plates

  • 임철규 (제주대학교 에너지공학과) ;
  • 허정환 (제주대학교 에너지공학과) ;
  • 정범진 (제주대학교 에너지공학과)
  • Lim, Chul-Kyu (Dept. of Nuclear and Energy Engineering, Applied Radiological Science Research Institute, Jeju Nat'l Univ.) ;
  • Heo, Jeong-Hwan (Dept. of Nuclear and Energy Engineering, Applied Radiological Science Research Institute, Jeju Nat'l Univ.) ;
  • Chung, Bum-Jin (Dept. of Nuclear and Energy Engineering, Applied Radiological Science Research Institute, Jeju Nat'l Univ.)
  • 투고 : 2010.12.15
  • 심사 : 2011.05.03
  • 발행 : 2011.07.01
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초록

기울어진 평판에서 발생하는 자연대류 열전달현상을 $R_{a_L}$ $1.69{\times}10^{11}$과 $7.23{\times}10^{12}$에 대하여 실험적으로 연구하였다. 유사성을 이용하여 열전달실험을 물질전달 실험으로 대체하였고 물질전달계로 전기도금계를 사용하였다. 평판의 기울기는 상향수평에서 하향수평까지 $10^{\circ}$씩 변화시켰다. 하향평판에서는 수직 벽면에 대한 자연대류 열전달 상관식에서 g 대신 g $cos{\theta}$로 대체함으로써 열전달계수를 구할 수 있다는 기존의 이론과 일치하는 결과를 얻었다. 상향평판의 경우 경계층이 벽면을 따라 발달되는 경우와 벽면으로부터 박리되는 2가지 영역으로 구분되는데 박리에 따른 열전달 증가를 확인하였다. 아울러 도금패턴을 이용하여 박리지점을 시각화하였고 박리지점에 대한 분석이 수행되었다.

Natural convection heat transfers on inclined flat plates were measured for Grashof numbers of $8.06{\times}10^7$ and $3.45{\times}10^9$ by using a copper sulfate electroplating system. The inclinations of the plates were varied from upward-facing horizontal to downward-facing horizontal. Test results for the downward-facing plate agree well with the existing theory that the Nusselt number can be calculated by replacing gravitational acceleration, g with g $cos{\theta}$ in the heat transfer correlation for the vertical plate. The natural convection flows for the upward-facing plate follow two distinct flow regimes: boundary layer regime and flow separation regime. The copper plating pattern for the upward-facing plates clearly reveals the flow separation points.

키워드

참고문헌

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