Experimental and numerical studies of laminar natural convection heat transfer from an isothermally heated narrow flat plate oriented at different angles of rotation

Abstract

The laminar natural convection heat transfer from isothermally heated narrow flat plates oriented at different angles of rotation is experimentally and numerically studied. The heated flat plate is narrow, i.e., has a relatively small width, w, to length, l, ratio, and is embedded in a plane adiabatic surface within which the heated plate can be oriented at different angles of rotation. The three-dimensional governing equations for geometrical assessment were solved numerically in terms of non-dimensional variables using finite volume-based solution. Model results for the average Nusselt number were obtained for a relatively wide range of non-dimensional variables included the Rayleigh number ranging from 1×10³ ≤ Ra ≤ 1×10⁸, non-dimensional plate width ranging from 0.15 ≤ W ≤ 1, and angle of rotation ranging from 0° ≤ α ≤ 90°. On the other hand, experimental results for the average Nusselt number were obtained for a narrower range of non-dimensional variables included the Rayleigh number ranged from 5.98×10³ ≤ Ra ≤ 1.18×10⁵, the angle of rotation ranged from 0° ≤ α ≤ 90°, and the non-dimensional plate width was fixed at 0.4. Additionally, a Prandtl number of 0.7 was used, which is the value for air in some of the applications that initiated this study. The model results are validated against present experimental results and existing correlations. The effects of these non-dimensional variables on the average and local Nusselt numbers for the heated flat plate were investigated. It was found that in some situations the non-dimensional variables have a significant effect on heat transfer rate from the heated flat plate. Correlations to calculate the average Nusselt number for the heated flat plate were developed.