Heat transfer characteristics of the closed tube aerosyphon

Abstract

The paper deals with heat transfer in the closed tube aerosyphon in which the upper section is cooled, the lower section is heated, and buoyancy forces are largely attributable to air bubbles introduced at the base of the device. Consistent with previous work, experimental data are used to demonstrate that substantial increases in heat transfer rates anse from increased advection and turbulence produced by the buoyant streaming. An attempt is made to describe the behaviour of the system in terms of bubble hydrodynamics. Predicted trends based on the behaviour of single bubbles are in general agreement with observations thus suggesting a simple physical basis for a complex convection system This flow model is consistent with the observed effects of aerator geometry and aeration rate, and may be used in establishing levels of confidence for extrapolation of an empirical correlation above or below the range of the variables measured.