Forced, natural and mixed-convection heat transfer and fluid flow in annulus: A review

Natural convection heat transfer in horizontal concentric annulus between outer cylinder and inner flat tube using nanofluid

Numerical Simulation of Natural Convection Between Two Elliptical Cylinders: Influence of Rayleigh Number and Prandtl Number☆

Optimal hydro-thermal characteristics of a porous annular elliptic pipe using response surface method

Experimental and numerical simulation study for natural convection heat transfer formed by uniformly heated horizontal elliptic and circular cylinders concentrically located in an isolated horizontal cylinder were investigated. Both ends of the annulus are opened. Experiments were carried out for Grashof number based on the hydraulic diameter of annulus ranges from 0.6397×10 6 to 5.836×10 6 . The elliptic inner cylinder orientation angles, ψ=0 o , 45 o , and 90 o , and for axis ratio of elliptic cylinder (minor/major=b/c) of 1:2, while the annulus diameter ratio for inner circular cylinder was 2. A numerical simulation was conducted by using commercial Fluent CFD software to investigate the steady laminar natural convective heat transfer for air between a heated elliptic and circular cylinder and outer circular cylinder. The numerical simulation covered three inclination angles of the elliptic inner cylinder ψ =0 o (the major axis is vertical), 45 o , 90 o , three positions of the circular inner cylinder (center, upper and lower position) and two values of heat flux: 165 W/m 2 and 1080 W/m 2 . The experimental results showed that the heat transfer process improves as Grashof number increases and is better in elliptic annulus than circular annulus where the orientation angle ψ=90 o at the same heat input. Two empirical equations are deduced for average Nusselt number as a function of Grashof number for both cases considered in this work. Theoretical results showed that the heat flux, the position of inner circular cylinder with respect to horizontal axis of annulus, and the angle of elliptic inner cylinder inclination have significant effect on the physical behavior of streamlines and isotherms inside the equivalent annular gap.

Natural Convection Heat Transfer in Horizontal Annuli with Inner Elliptic and Circular Cylinder

The authors express the Boussinesq equations of the laminar thermal and natural convection, in the case of permanent and bidimensional jlow, in an annular space between two confocal elliptic cylinders. A new calculation code using the finite volumes with the primitive functions (velocity-pressure formulation) and the elliptic coordinates system is proposed. The Prandtl number isfixed at 0.7 (case of the air) with varying the Rayleigh number. The efJect of the geometry of the interior (...)

/pdf/numerical-study-of-bidimensional-steady-natural-convection-406e7ibp5g.pdf

Numerical Study of Bidimensional Steady Natural Convection in a Space Annulus Between Two Elliptic Confocal Ducts Influence of the Internal Eccentricity

M. Daguenet

Papers

Numerical Study of Bidimensional Steady Natural Convection in a Space Annulus Between Two Elliptic Confocal Ducts Influence of the Internal Eccentricity