TITLE : Flow and heat transfer in an electronic cabinet
 

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

NOTES :

Three-dimensional, forced convection, Cartesian computational grid

Description of the problem:

 
• This case contains six chips mounted on a PCB;
• The cabinet is half cylindrical cross sectional; air is extracted from fan mounted at top and pushed out of the system via a bottom vent, click here to see External structure of the cabinet and Internal structure of the cabinet;
• Each chip has 1 W heat output;
• Fan works at a fixed velocity of 1 m/s; and
• Dimensions of parts are as follows:

Part	Dimension (side*side*thickness) (mm)	Model thermal conductivity (W/mK)	Object type in HOTBOX
Cabinet size (half cylinder)	Radius of 140, thickness of 70	-	Blockage
Chip	20*20*5	30	Blockage
PCB	140*100 (2-D)	-	Plate
Fan	70*70 (2-D)	-	Fan
Bottom Vent	70*70 (2-D)	-	Aperture

Solution procedure:

 
• Turbulence is modelled by the LVEL method;
• Material properties are imported from the User-defined property file 'Props'; and
• Fixed pressure boundary condition is applied at the bottom vent.

Results

The following figures show the temperature distributions and velocity vectors of the thermal cabinet with six chips each containing 1W within the half-cylinder enclosure.

Temperature contours across the chips

Temperature contours not across the chips

Velocity vectors across the chips

Velocity vectors not across the chips

Conclusions:

This case demonstrates how HOTBOX-VR handles

 
• irregular boundary using cartesian co-ordinates; and
• large disparity in component dimension and thermal conductivity.