NATURAL CONVECTION IN ENCLOSURES CONTAINING TUBE BUNDLES.

The authors present a condensed review of the literature for the vertical cavity and annulus and a report of new work for the vertical annulus and vertical rod bundle. In both cases, power dissipation in the heated rods is uniform along the axis, and hence the thermal boundary condition for the rod wall is constant heat flux. For the rod bundle, new results are presented for local temperature distributions on individual rods, average heat transfer coefficients for individual rods, and average Nusselt numbers for the entire bundle. A general correlation for an N multiplied by N bundle in an isothermal cylinder is developed, and an approximate model is developed to express heat transfer in this system similar to that in a vertical annulus. Some new results for the vertical annulus have also been obtained which shed light on the effects radius ratio and aspect ratio on average Nusselt number.