Three-dimensional flow in a closed thermosyphon

Abstract

A numerical and experimental study has been made of the three-dimensional flow and heat transfer by natural convection in a closed, rectangular thermosyphon. At low Rayleigh numbers, the flows in the two halves of the cavity remain separate, with heat transfer across the mid-height plane occurring only by conduction. At increasing Rayleigh numbers, an exchange process of increasing complexity occurs. The numerical solutions were used to explore this process and to predict flow patterns which were found to resemble closely those observed during previous investigations of cylindrical thermosyphons. The results were verified by a flow visualization study. Heat-transfer rates are presented and augment previous data for higher values of the governing parameters.