Natural Convection Heat Transfer in Vertical Parallel Plates with a Closed Lower End : 1st Report, Numerical Analysis

Abstract

On natural convection heat transfer of two vertical parallel plates with a closed lower end, a numerical analysis was performed for Grashof numbers ranging from 10⁴ to 10⁷, the ratio of hot and cold wall temperatures ranging from 0.1 to 1 and a Prandtl number of 0.71, under the condition of constant wall temperature. The local Nusselt number is slightly larger than that of the experimental results by Siegel in the range of 10⁶ < Gr < 10⁷. For small values of the wall temperature ratio, negative heat transfer coefficients of the cold wall are observed. The average Nusselt number can be expressed as a function of the distance of parallel plates and the Grashof number based on it ; Nu_s =C(Gr_sS²)ⁿ where C and n are functions of the wall temperature ratio. Circulating flows are found in the vicinity of the end of the parallel plates.