تصميم عن طريق برنامج ال mathcad

A thermal engineer is to design a 10

× 7

× 7

box in which two printed circuit boards

(PCB) made of aluminum are passively cooled by natural convection. An internal heat

sink with a cold plate attached to one of the walls of the box is considered. All the walls

are insulated except the cold plate, which is maintained at a certain temperature using

a thermoelectric cooler that is not included in this project. Each board has a thermal

dissipation up to 12 W. Design the box, including both the PCBs and the heat sink, by

determining the cold plate temperature in order to maintain the temperature of the PCBs

less than 180◦

F. You may look at Tutorial II in Appendix F. The dimension of the PCB

is open to students, so that every student may have a different size. Develop a MathCAD

model for the internal heat sink for the given heat dissipation. Note that the fin size

of the heat sink in the box should be adequate to allow sufficient air flow at the top

and bottom. Design the heat sink using MathCAD. You should figure out analytically

the average internal air temperature and the cold plate temperature to achieve the design

requirement. Construct the three-dimensional (3-D) geometry for the box, including two

PCBs and a heat sink with a cold plate, using SolidWorks as a design tool.

Finally,

find by trial and error a proper (optimum) temperature of the cold plate to maintain the

PCB temperature below 180◦

F. Note that this problem does not include the thermoelectric

cooling, but the cold plate temperature must remain as high as possible to minimize the

power consumption of the thermoelectric cooling device.