Simulating a Heatsink

Hi,

First, I'd like to say Im new to Usenet in general. I lurk about
quite a bit, but this is my first post.

Ok, the question. I would like to simulate and project the movement
of heat from a source, through the heatsink and into the air. I have
a general idea, but its only vague ideas. Are there any good
resources/tutorials/guides that can explain this.

Ultimately, I want to create an application (for the computer) that
takes a heatsink design and mutates its attributes slightly to create
a new 'generation'. I need to then simulate how well it can conduct
and radiate heat, as well as convection (which apparently is very
difficult to simulate).

Im a honors 10th grader, so thats where my math and science skills
lie.

Thanks, I really appreciate any help.
-Zach Tong

"Zachary" <[Only registered users see links. ]> wrote in message
news:[Only registered users see links. ]...

Start with Newton's Law of Cooling
[Only registered users see links. ]

Realize that you have THREE heat reservoirs to consider, the heat source,
the surrounding fluid, and the heat sink.

The purpose of the heat sink is to take heat away from the heat source. It
is therefore useful to have a heat sink that has a high C-sub-p in Eq (1).
A high heat capacity allows the heat sink to hold more heat energy per
degree of temperature increase.

Having a good thermal contact between the heat source and the heat sink is
also useful, which is why heat sinks are often applied with a special
thermally conductive adhesive:
[Only registered users see links. ] for example.

The other part of the usefulness of heat sinks comes in their ability to
transfer heat to the surrounding fluid medium. This is facilitated by a
good flow of the medium (cooling fans), by a high surface-to-volume ratio in
the heat sink (fins), and my a high thermal conductivity in the material of
which the heat sink is made (usually a metal - electrons in a metal conducti
on band are excellent conductors of heat). In special applications the
fluid in contact with the heat sink may be a special gas or liquid (I have
used liquid nitrogen and liquid helium for cryogenic applications; other
fluids used are often called refrigerants and may be selected to insure that
the temperature remains within a certain range - a slurry of dry ice and
either acetone or alcohol will equilibrate at about -34° C).

Finally, the geometry of the interface between the heat sink and the fluid
medium will affect its efficiency. Fins or other structures that maximize
the surface to volume ratio of the heat sink (increasing K in Eq (2)) will
expedite transfer of heat from the heat sink to the medium, provided they do
not restrict the flow which can result in localized heat accumulation in the
fluid around the heat sink, reducing the effective temperature difference
(T - T-sub-s) in Eq (2). You want to maximize the *product* of the two
quantities, and increasing one will usually result in a decrease of the
other, so there is a trade-off.

This should give you something to think about over the holidays.


Tom Davidson
Richmond, VA