At 04:13 PM 1/25/2012, Alan J Fletcher wrote:
Am I right in thinking that if the Hyperion is roughly cylindrical,
then the heat flow between the inner and outer surfaces is calculated as in
A hollow cylinder
<http://en.wikibooks.org/wiki/Heat_Transfer/Conduction#A_hollow_cylinder>
For a cylinder of length L : inner R1 at T1, outer R2 at T2
Q = 2 pi k (T1 - T2) / ln ( R2/ R1 )
Since this cylinder is surrounded by another insulating cylinder we
don't have to worry how it gets rid of the heat
(radiation,convection,conduction) to the surrounding air.
Here's a method:
http://www.chooyuchem.com/product_tputty.html
1. Suppose the hyperion is roughly cyclindrical, with inner radius R1
and outer R2
2. Wrap the roughly cylindrical hyperion in a HIGH conductivity putty
(5 W/mK), forming a cylinder of R3 at T3
High conductivity is chosen to even out any hot spots.
3. Wrap that cylinder with another cylinder of LOW conductivity (2
W/mK), forming a cylinder of R4 at T4
4. Wrap that with another HIGH conductivity cylinder with radius R5 at T5
5. Use VERY good insulation on the ends of the cylinder (eg aerogel)
The two high-conductivity zones will even out any irregularities on
the surface of the hyperion (shape and thermal profile) AND
any irregularities on the outside surface (different convection, conduction)
I think that calculating Q from T3 to T4 would be very accurate.
