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

The Korean Society of Mechanical Engineers (대한기계학회)
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Heat Transfer Enhancement of Water Spray Cooling by the Surface Roughness Effect

표면거칠기 효과에 따른 스프레이 냉각의 열전달 향상 연구

  • Lee, Jung-Ho (Dept. of Energy Plant, Environment and Energy Systems Research Division, Korea Institute of Machinery and Materials (KIMM))
  • 이정호 (한국기계연구원 그린환경에너지기계연구본부 에너지플랜트연구실)
  • Published : 2010.02.01
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Abstract

Water spray cooling has been widely used in a variety of industrial applications. The present study concentrated on quantitative measurements of the heat flux and heat transfer coefficient by water spray as it impinges on the rough surface of a hot steel plate at $900^{\circ}C$. A novel experimental technique was developed for a hightemperature heat flux gauge with a test block, cartridge heaters, and thermocouples that was used to measure the surface heat flux information on the hot steel plate for local heat flux measurements. The roles of the surface roughness on heat transfer are presented in this paper for well-characterized four rough surfaces with average rms roughness heights of $40-80{\mu}M$. The results show that the local heat transfer for rough surfaces is higher than that for a smooth surface. Heat transfer can be significantly increased by the presence of surface roughness elements, which can disrupt the thin thermal boundary layer. In addition, the heat transfer enhancement mechanism on a rough surface can be investigated by a different boiling regime.

수분류 스프레이 냉각은 많은 산업적인 응용분야에 넓게 사용되고 있다. 본 연구는 수분류 스프레이가 표면거칠기가 주어진 $900^{\circ}C$ 고온강판의 표면에 충돌하는 경우, 열유속 및 열전달계수의 정량적인 측정을 통해 표면거칠기가 수분류 스프레이 냉각에 미치는 영향을 고찰하였다. 이 때의 국소 열유속은 시편, 카트리지히터, 열전대의 조합으로 고안된 고유의 열유속게이지를 제작하여 엄밀하게 측정되었다. 평균 표면거칠기 높이를 기준으로 40, 60, $80{\mu}M$의 3 가지 표면과 매끈한 표면에 대한 수분류 스프레이 냉각 의 열전달 현상이 비교 및 평가되었다. 표면거칠기가 주어진 표면에서의 돌출물은 얇은 열 경계층두께를 통과할 수 있기 때문에 표면거칠기가 주어진 경우에 열전달은 뚜렷하게 증가하였고, 표면거칠기의 의한 열전달 향상 기구는 서로 다른 비등영역에 대해 구분하여 조사되었다.

Keywords

References

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Cited by

  1. Effect of Water Temperature on Heat Transfer Characteristic of Spray Cooling on Hot Steel Plate vol.35, pp.5, 2011, https://doi.org/10.3795/KSME-B.2011.35.5.503