TITLE : HOTBOX EXAMPLE :

NATURAL CONVECTION IN AN ENCLOSURE WITH SINGLE  HEATING BLOCK

BY :	CHAM Development Team - F Liu	DATE :	1999
FOR :	Demonstration Case
PHOENICS Version :	HOTBOX VR

NOTES :

Three-dimensional, steady flow, natural convection, conjugate heat transfer, Cartesian computational grid

Description of the problem:

• The enclosure has a heating component and a conducting board mounted on one boundary. The dimensions of the enclosure are 30mm(L) x 20mm(H) x 10mm(W); the component is of 6mm x 5mm x 2mm and mounted on the conducting board, whose thickness is 1mm. click here to see  Overall view of the enclosure
• Both walls at z=0 and 10mm are fixed at 30°C; and all other walls are assumed adiabatic.
• Thermal conductivities for the component, board and air are 30, 1 and 0.026 W/(m K), respectively.

Solution procedure:

• Turbulence is modelled by the LVEL method;
• Buoyancy effect is included using Boussinesq approximation; and
• Material properties are imported from the User-defined property file 'Props'.

Results:

All the pictures as shown below are created via the Virtual Reality Graphic Interface, a strong feature of HOTBOX-VR.

1. Velocity vectors
Velocity vector across the component in z direction
Velocity vector not across the component in z direction
Velocity vector across the component in x direction

From the figures above, the velocity predicted is symmetric along the x mid-plane, which is also evident from the temperature and pressure contours followed. The most of air flow is circling within and near this mid-plane.

2. Temperature contours
Temperature contour across the component in z direction
Temperature contour not across the component in z direction
Temperature contour across the component in x direction

It is clearly seen that the circling air is cooling the component and the temperature distribution around it is very much following the flow pattern.

3. Pressure contours
Pressure contour across the component in z direction
Pressure contour across the component in x direction

Conclusions:

• This case demonstrates how HOTBOX-VR handles natural convection flow and heat transfer in an enclosure with heating block;
• The configuration could be used as a component inside a complex electronic equipment; and