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바닥이 가열되는 정 6면체 공간내의 열전달
Heat Transfer in a Cube Heated from Below
HWAHAK KONGHAK, April 1990, 28(2), 196-204(9), NONE
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Abstract
본 연구에서는 바닥이 가열되는 정 6면체 공간내의 열전달을 이론적으로 해석하였다. 상온 부근에서도 복사의 영향과 벽면의 열전도가 중요함에 착안하여 벽면간의 복사, 공간내의 난류성 대류와 벽체의 열전도에 관한 방정식들로 구성된 모델방정식을 유도하고 이의 해를 구하였다. 경계층을 제외하고는 공간내의 온도가 일정하다는 새로이 제안된 "Isothermal core postulate"와 내벽면이 grey body로 구성되어 있다는 가정을 기본으로할 때, 복사에 관한 방정식은 2-D의 적분방정식으로, 벽체내의 열전도에 관하여는 3-D의 라플라스 방정식으로 주어지고, 열전도식의 경계조건과 총괄에너지 수지식에 대류에 관한 항이 포함되었다. 기준변수 set을 온돌방에성의 값을 고려하여 정하고, 이를 중심으로 파라미터값을 변화시키면서 parametric study를 수행하였다. 본 연구의 결과 기본가정 "Isothermal core postulate"의 타당성이 확립되고, 온돌방의 경우 바닥으로부터의 열속 중 복사와 대류가 서로 대등한 값을 가짐을 알 수 있었다.
In this research, a theoretical analysis was performed on the heat transfer in a cube heated from below. Being noted that radiation and conduction effects were not negligible in the room temperature range, model equations were derived and solved on the radiation between walls, turbulent convection inside the cube and conduction through walls based on the newly proposed "isothermal core postulate". The radiation equation was a classical 2-D integral equation and the conduction equation was a 3-D Laplace equation. The convection term was included in the overall energy balance and boundary conditions imposed on the Laplace equation. Parametric studies were performed by varying system parameters from a reference set which could be suitable to "ondol" system. Two major conclusions from this study were that the isothermal core postulate was appropriate and half of the heat flux from the bottom was due to radiation.
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Elder JW, J. Fluid Mech., 35, 417 (1969)
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Cess RD, Adv. Heat Trans., ed. T.F. Irvmeand J.P. Hartnett, 1, 38 (1967)
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