Heat Transfer Characteristics of Inclined Annular Insulation Layer

Numerical analysis has been performed on three-dimensional natural convection in thermal insulation layer enclosed with concentric inclined cylinders. Darcy’ law and Boussinesq, approximation are assumed to be applicable. Governing equations are numerically solved by means of successive over-relaxation methods for ranges of RaDa (a product of Rayleigh number Ra and Darcy number Da) from 1 to 1,000 and δ (an angle of inclination of cylinders from the horizon) from 0 to Π/2. Results show that the fluid particle path draws the co-axial double spiral and that the local Nusselt number Nu₁ on the inner cylinder wall has its maximum value at Φ=0 and ξ=0 (bottom end), while Nu₂ on the outer cylinder wall has its maximum at ξ=ξ_max (top end) and Φ with some deviation from Π. However, the average Nusselt number depends largely on only RaDa and is hardly affected by the inclination.