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

  • 제34권5호
  • /
  • Pages.481-489
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  • 2010
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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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수직관내 발달 유동의 층류혼합대류 연구

Study on Laminar Mixed Convection of Developing Flow in Vertical Pipe

  • 투고 : 2009.09.02
  • 심사 : 2010.03.03
  • 발행 : 2010.05.01
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초록

수직관내 발달 유동의 층류혼합대류에 관한 본 연구는 Re 1,000에서 3,000, $Gr_H\;10^5$에서 $10^8$, Pr 2,000 에서 7,000 그리고 종횡비 1부터 7에 대한 범위에 대해서 수행되었다. 유사성(Analogy)의 원리를 이용하여 수직관내 발달 유동의 층류혼합대류 열전달계를 물질전달계로 모사하였다. 물질전달계로써 Nu 수는 기존의 문헌들의 그것들보다 상당히 큰 값이었는데, 이는 본 실험의 높은 Pr 수 때문이다. 본 연구에서의 종횡비는 완전발달 할 만큼 크지 않았기 때문에, 실험 결과는 긴 수직관내 혼합대류 유동보단 평행평판에서의 혼합대류 유동과 유사하였다. 본 연구의 결론으로서 낮은 종횡비와 $Gr_H$ 수를 갖는 수직관내 발달 유동의 층류혼합대류 유동은 수직 평판에서의 층류혼합대류 유동과 유사한 거동을 보인다는 것이다. 그리고 종횡비와 $Gr_H$ 수가 증가할 때 유체의 거동은 수직관내 완전발달 유동과 유사한 현상을 보였다.

Experiments on laminar mixed convection in a vertical pipe were performed for the Re range 1,000-3,000, the $Gr_H$ range $10^5-10^8$, the Pr range 2,000-7,000, and aspect ratio range 1-7. Using the analogy concept, heat transfer systems were simulated by mass transfer systems. A cupric acid.copper sulfate electroplating system was adopted as the mass transfer system, and the mass transfer rates were measured. The measured Nu values were far greater than those previously reported because of the large value of pr in this experiment. As the aspect ratio in this study was not sufficiently large for the flow to be fully developed, the test results were similar to those for mixed convection on a vertical plate rather than that inside a long vertical pipe. It was concluded that the behavior of laminar mixed convection of a developing flow in a vertical pipe at a low aspect ratio and low $Gr_H$ is similar to that of laminar mixed convection in the vertical plate. As the aspect ratio and $Gr_H$ increase, the laminar mixed convection phenomena becomes similar to that observed in a fully developed flow in the vertical pipe.

키워드

참고문헌

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피인용 문헌

  1. Effect of Adiabatic Sidewalls on Natural Convection in a Rectangular Cavity vol.34, pp.9, 2010, https://doi.org/10.3795/KSME-B.2010.34.9.825
  2. Experiments on Natural Convection on the Outer Surface of a Vertical Pipe by Using Fluids with High Pr Number vol.35, pp.1, 2011, https://doi.org/10.3795/KSME-B.2011.35.1.033
  3. Visualization of Natural Convection Heat Transfer on Horizontal Cylinder Using the Copper Electroplating System vol.35, pp.1, 2011, https://doi.org/10.3795/KSME-B.2011.35.1.043
  4. Natural Convection Heat Transfer on Inclined Plates vol.35, pp.7, 2011, https://doi.org/10.3795/KSME-B.2011.35.7.701