Fluid flow and convection heat transfer in concentric and eccentric cylindrical annuli of different radii ratios for Taylor-Couette-Poiseuille flow

Hosny Abou-Ziyan,Reda Ameen,Khairy Elsayed

doi:10.1177/16878140211040731

Abstract

This paper presents the results of fluid flow and convection heat transfer in concentric and eccentric annuli between two cylinders using a three-dimensional computational fluid dynamics model. Effects of rotational speed ( n = 0, 150, 300, and 400 rpm) and eccentricity (ε = 0, 0.15, 0.3, 0.45, and 0.6) on axial and tangential velocity distribution, pressure drop and forced convection heat transfer are investigated for radii ratios (η) of 0.2, 0.4, 0.6, and 0.8, Reynolds number 2.0 × 103–1.236 × 105, Taylor number 1.47 × 106–1.6 × 1010, and Prandtl number 3.71–6.94. The parameters cover many applications, including rotary heat exchangers, mixers, agitators, etc. Nusselt numbers and friction factors for stationary and rotated concentric and eccentric annuli are correlated with four dimensionless numbers. The results revealed that when the speed of the inner cylinder increases from 0 to 400 rpm, the friction factor increases by 7.7%–103% for concentric and 8.2%–148% for eccentric annuli, whereas Nusselt number enhances by 37%–333% for concentric and 44%–340% for eccentric annuli. The radius ratio has a substantial effect on the heat transfer and pressure drop in annuli. The eccentricity enhances the heat transfer up to 12%, whereas its effect on the friction factor is not monotonic as it depends on Reynolds number, radii ratios, and rotational speed.

Highlights

Fluid flow and heat transfer in the annular space between two circular cylinders, where the inner cylinder is rotating and the outer cylinder is stationary, is encountered in many types of equipment and engineering applications
The investigation of fluid flow and heat transfer in concentric and eccentric annuli with a stationary adiabatic outer cylinder and a stationary or rotating isothermal inner cylinder is conducted for rotational speeds 0, 150, 300, and 400 rpm, radii ratios 0.2, 0.4, 0.6, and 0.8 with eccentricities 0.0, 0.15, 0.30, 0.45, and 0.6
The correlations facilitate the design of rotating and stationary heat exchangers and other applications based on the annular space between fixed and rotating cylinders

Summary

Introduction

Fluid flow and heat transfer in the annular space between two circular cylinders, where the inner cylinder is rotating and the outer cylinder is stationary, is encountered in many types of equipment and engineering applications. The wide annular space takes place in numerous industrial applications, including rotating heat exchangers, mixers, agitators, around nuclear fuel rods in reactors, and wells drilling (the annulus between a borehole and a drill pipe).[1]. The fluid flow in the annular space between two cylinders may be classified into a Couette flow, TaylorCouette flow, Poiseuille flow, and Taylor-CouettePoiseuille flow. In Poiseuille flow, both cylinders are stationary with the imposed axial flow, whereas for TaylorCouette-Poiseuille flow, the outer cylinder is stationary, and the inner cylinder is rotating with the imposed axial flow.[2] In addition, other applications may include imposed flow in the radial direction.[3]

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