NATURAL CONVECTIVE HEAT-TRANSFER FROM OPEN VERTICAL TUBES

Natural convection heat transfer in vertical tubes is described by a o ne-dimensional dispersion model similar to that used previously for fl uid mixing in the presence of an unstable density gradient. Temperatur e profiles have been measured in air in 2 m high insulated vertical tu bes (21.3, 24.5, 27.7 cm internal diameter), closed at the bottom and open at the top, and heated at the bottom with a known heat flux. The effective mixing lengths for eddy heat transport are of the same order as the tube diameters.