Fluid Flow and Heat Transfer in an Annulus with a Heated Core Tube

Abstract

Fluid friction, velocity distribution and heat transfer at the inner wall of a smooth concentric annulus in turbulent flow are dealt with in this paper. The results and correlations of a number of previous investigators are briefly reviewed. New friction, velocity-distribution and heat-transfer data from experiments with air flowing turbulently in an annulus of radius ratio 2.248 are presented. The outer-wall friction factors and velocity data have been correlated by the methods used for smooth circular tubes. Based on these correlations, and the analogy between heat transfer and fluid friction, a semi-theoretical equation for the heat-transfer coefficient is proposed. The suggested equation suits the author's experimental results well, and is applicable for all commercial radius ratios. The range of Prandtl number for which the equation is valid has not been determined.