Free Convection Heat Transfer in a Stably Stratified Fluid between Coaxial Cylinders (Heating from the Inner Cylinder and Cooling from the Outer Cylinder).

Abstract

An experimental study was performed on free convection heat transfer in a stably stratified fluid between coaxial cylinders. The stratified layer was formed using a sucrose aqueous solution, and was heated from the inner cylinder at constant heat flux and cooled from the outer cylinder at constant temperature. As a result of generation of cellular convection layers in the stratified fluid the local heat transfer coefficient at the heating surface becomes larger in the upper part and smaller in the lower part, since the heating surface is below in the former case but above in the latter case. This distribution of the local heat transfer coefficient is quite different from that for a nonstratified fluid, where the local heat transfer coefficient decreases in the upward direction. The transient characteristics of the heat transfer and flow in the stratified fluid was also clarified comprehensively in the present study.