ISSN Online: 2379-1748
ISBN Flash Drive: 978-1-56700-431-1
ISBN Online: 978-1-56700-430-4
First Thermal and Fluids Engineering Summer Conference
NUMERICAL STUDY OF THE EFFECT OF VENT SIZE ON NATURAL CONVECTIVE HEAT TRANSFER FROM A SQUARE HORIZONTAL ISOTHERMAL HEATED SURFACE MOUNTED IN A FLAT ADIABATIC BASE AND SURROUNDED BY A PROTECTIVE COVER
Abstract
In some applications electronic components are surrounded by a protective surface. This surface is usually
vented to allow natural convective cooling flow of air over the . The vents in the protective surface
must usually be small to ensure adequate protection. To investigate in a basic way the effect of vent size on
the heat transfer rate in such situations heat transfer from a square, isothermal with a vented
covering surface has been numerically studied. The covering surface is assumed to have a square crosssectional
shape that just covers the heated element. The covering surface has a single inlet vent around the
base of the covering surface and a single outlet vent around the top of the covering surface, these two vents
having the same size. Conditions under which laminar, transitional, and turbulent flow can exist have been
considered. The k-epsilon turbulence model with full account being taken of buoyancy force effects was
used. The governing equations have been numerically solved using the commercial CFD solver ANSYS
FLUENT©. The solution parameters are the Rayleigh number, the dimensionless size of the vents, the
dimensionless height of the cover top above the heated element, and the Prandtl number. Results have only
been obtained for a Prandtl number of 0.74. The effects of the dimensionless size of the inlet and outlet vents
and of the dimensionless height of the top of the covering surface above the heated element on the mean
Nusselt number for a range of Rayleigh numbers has been studied.