Experimental Study on Natural Convection Heat Transfer With Density Inversion of Water Between Two Horizontal Concentric Cylinders

Abstract

An experimental investigation concerning the effect of density inversion on steady natural convection heat transfer of water between two horizontal concentric cylinders with diameter ratio ranging from 1.18 to 6.39 is carried out. Water, as a testing fluid, has the maximum density at 4°C. Temperature of the inner cylinder is maintained at 0°C, while temperatures of the outer cylinder are varied from 1 to 15°C, with Grashof number ranging from 3.2 × 101 to 2.7 × 105. Photographs and qualitative description of the flow patterns, temperature profiles, local and average Nusselt number are presented. From the present experimental investigation, it is demonstrated that the effect of density inversion is unexpectedly large and the average Nusselt number is a peculiar function of temperature difference between outer and inner cylinder, unlike the previous results on common fluids without density inversion.