ISSN Online: 2377-424X
ISBN Print: 0-89116-559-2
International Heat Transfer Conference 8
NATURAL CONVECTION HEAT TRANSFER WITHIN ENCLOSURES AT REDUCED PRESSURES
要約
Natural convection heat transfer in air within enclosures has been investigation over the pressure range of 2,670 to 86,180 Pa (20−646.4 mm Hg). Dimensionless correlations have been generated from the data. The best correlation found was: NuL = .142 Ra.31 where L is the hypothetical gap width. The Rayleigh number in the experiments ranged over 1 × 103 − 2 × 106. These equations, obtained from low pressure data, represent very accurate correlations at very low Rayleigh numbers. The geometries used were heated isothermal cylinders and cubes mounted concentrically within a cooled isothermal cubical enclosure. Temperature profiles at four positions (0°, 34°, 80° and 160° from the upward vertical) were measured for the cylinder-cube case. The thickening of the boundary layer at low pressures and the region of constant temperature between the bodies at high Rayleigh number were clearly observed.