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Re: Peltier element in space ?



Hi Bob,

Yes, you need some physical steering of the solar panels to get one side 
always to the sun and the other side in the dark. When I am right a white 
colored surface does not radiate any heat radiation, so it will not get very 
cold. I think you must paint both sides black, one absorbs the sun radiation 
very much, and on the cold side the black colored side will radiate its heat 
away in space...

With qubic satellite bodies it also is not very efficient I think because 
you have the payloads in between. The best is I think panels asside, like 
the big commercial GEOs have.
The distance between the hot and cold side is very small, only the thickness 
of the peltier, that make it more efficient...

But maybe with the use off heat-pipes it can also be used in qubic 
satellites... its just a way of thinking out some solution :o)

73 de PE1RAH, William
in the beautiful city of Buenos Aires, Argentina
---


>From: "Robert Bruninga" <bruninga@usna.edu>
>To: <pe1rah@hotmail.com>
>CC: <amsat-bb@AMSAT.Org>
>Subject: Re: [amsat-bb] Peltier element in space ?
>Date: Tue, 24 Feb 2004 19:06:33 -0500
>
> >>> "William Leijenaar" <pe1rah@hotmail.com> 2/24/04 11:08:33 AM >>>
>Hi AMSATs,
>
> >Somebody knows if peltier-elements are ever used to power a satellite
>???
>
>The hard part is keeping one side always hot and the other
>always cold.  This means active attitude control and therefore
>a very expensive satellite that can afford solar cells..
>
>I also had a design for GEO orbit that used solar-sail concepts
>to keep one side always facing sun.  But a GEO is also very
>expensive and again, cheaper then to put solar cells on that side.
>
>My 3rd design used a CUBE with a center BLACK section
>surrounded by an equal area of WHITE on all 6 sides.
>Then internally all of the BLACK surfaces are conducted
>to the HOT side of the Peltier junctions and the WHITE
>surfaces are all conducted to the COLD sides of the
>junctions so that there is always a heat flux.  Its not much,
>but works:
>
>http://www.ew.usna.edu/~bruninga/craft/peltier.gif
>
>But again, efficiency is an order of magnitude better to
>just use solar cells.  So we never could find a practical
>application
>
>de WB4APR, Bob

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