Passive cooling of discretely heated closed and partially open enclosures by combined conduction, natural convection and radiation

Computational and experimental investigations on combined conduction, natural convection and radiation heat transfer in discretely heated complete and vented three-dimensional enclosures are carried out. Both vertical and horizontal orientations of the heated surfaces are studied. Influence of computational boundary conditions is evaluated, especially the applicability of approximate boundary conditions on the enclosure apertures. Radiation is found to significantly effect the flow patterns and overall heat transfer. Venting configurations are found to affect heat transfer for vertically and horizontally heated enclosures in a different fashion. Asymmetric flow and temperature patterns are found in top vented horizontal enclosures, impacting the temperature profiles of the component and substrate. Two other thermal enhancement enclosure boundary conditions are found. Also, enhancement by heat sinking is studied computationally and experimentally. The results are found to be orientation dependent. Effectiveness of a porous media model is demonstrated for modeling pin-fin heat sinks.