Thermally Optimum Spacing between Inner Plates in Natural Convection Flows in Cavities by Numerical Investigation

Buoyancy-driven airflow that included two isothermal inner plates established in a vented cavity is investigated numerically. The thermally optimum wall-to-wall spacing of the immersed channel, as well as its dependence with respect to the relevant governing parameters, are determined. Results are presented as a function of the aspect ratiob/Hfor a wide range of Rayleigh numbers Ra-H. A logarithmic correlation for the optimum (b/H)(opt)as a function of Ra(H)is presented. In addition, since the outlined configuration might be subject to intense heating conditions, the influence of considering variable thermophysical properties is also included in the analysis. In fact, an appreciable influence of the variation of properties on (b/H)(opt)is also detected for a representative value of Ra-H= 10(9). Obtained results can be directly applied to the optimization of electronic equipment cooling, or even to thermal passive devices in buildings.