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RE: Peltier element in space ?



These have been used before in space, by using a nuclear source to generate
the heat, and cooling the other side by radiating heat away. 

The solar-system-exploring craft (pioneer / voyager) used this (at first
try, I found http://voyager.jpl.nasa.gov/spacecraft/index.html).
This was necessary because there aint much sun light near pluto, and nuclear
source can last a long time.

As bob suggests, If you already intend on using sun light as the power
source, solar cells are much more efficient.
(Although Possibly an advantage of peltier is their reliability? - I dont
know).

If you look at the problem of getting power in a limited size and weight
without using sun, other alternatives are 
- nuclear ( various conversion-to-electriticy methods are possible eg
steam-turbine-generator!).
- Beaming power from earth using laser or microwave.
- Possibly absorbing energy  through gravity using mechanics of orbit.?
- Chemical (Batteries , petrol etc)
DAve
vk5dsm

-----Original Message-----
From: Robert Bruninga [mailto:bruninga@usna.edu]
Sent: Wednesday, 25 February 2004 10:37
To: pe1rah@hotmail.com
Cc: amsat-bb@AMSAT.Org
Subject: Re: [amsat-bb] Peltier element in space ?


>>> "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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