Three-dimensional numerical simulation of natural convection heat transfer in an inclined cylindrical annulus

A numerical study of natural convection heat transfer in an inclined cylindrical annulus has been conducted. The inner cylinder of the annulus is maintained at uniform heat flux and the outer cylinder at constant temperature. The two end walls are assumed to be insulated. A numerical code has been developed to calculate the steady state three-dimensional natural convection in an inclined cylindrical annulus, and the research emphasis is placed on the influences of inclination angle α and modified Rayleigh number Ra* on the natural convection heat transfer in the annulus. Computations were carried out in the ranges of 0° ≤ α ≤ 90*, 2.5 × 10⁵ ≤ Ra* ≤⁷ and Pr = 0.7 with fixed aspect ratio of H = 28.97 and radius ratio of K : 3.33. The numerical results are compared with the experimental correlations from the literature and the inclination angle effect on heat transfer is found to be insignificant. Detailed results of heat transfer rate, temperature, and velocity fields are presented for the case of α = 45° and discussion is also made concerning the comparison between the numerical aad experimental results for the specific case of α=90°.