Characteristics of Natural Convection Heat Transfer in an Array of Discrete Heat Sources

Abstract

This study aims to investigate experimentally the natural convection flow over an array of discrete surfaces mounted on a flat vertical substrate. The investigation covers the case where the discrete surfaces/substrate unit forms a wall of a closed cavity. Experimental measurements of the flow and thermal fields were conducted. The experimental study is aimed at investigating the influence of the Rayleigh number on the velocity and thermal fields inside the cavity. Two cases of heat source distribution were considered: uniform heat source distribution and non-uniform heat source distribution. Measurements of vertical and horizontal velocity components were obtained for three heating values: 10, 15, and 20 W corresponding to Rayleigh number values of Ra = 9.06 ×  10⁹, Ra 1.19 ×  10¹⁰, and Ra 1.41 ×  10¹⁰. For each case, the velocity measurements were conducted at three different vertical locations, located at the middle of each of the three heaters. Velocity measurements were also obtained for non-uniform heater distribution at Ra 9.53 ×  109. The energy loss was found to be about 10% of the power input in each case. Empirical correlations were obtained for the data for uniformly distributed heaters.

Keywords:

• natural convection
• heat transfer
• heat sources