Date: Thu, 11 Aug 94 17:08:18 EDT
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: cs@karin.att.com (Cetin Seren)
Subject: Solid State A/C
Interesting stuff about the Peltier devices and the Rovox Technology.
It seems that the Rovox technology is still based on the Carnot cycle, and, if
my memory of those horrendous thermodynamics courses is accurate, the
theoretical limit of efficiency to the Carnot cycle is 25%, i.e., you have to
put in 4 units of energy for every unit of energy you suck out of the
chamber that is being cooled. In general, if I'm not mistaken, the
efficiency of air conditioners run around 12-15% (my data is probably old
and misunderstood -- please correct if so)...
I do not know what the Peltier technology is based on -- it sounds like
a reversed thermocouple to me. I wonder what it's theoretical limit of
efficiency is, just out of curiosity.
BTW, thanks to Charles Vaughan for the quick calculations -- they
gave me a good perspective. I'll tend to agree with the person who
made the comment with the 10hp out 130 example. It does seem like
it should be possible to roll completely SOLID State technology for
air conditioning -- remember, the bright side is that Peltier technology
involves only one moving part component: the fan. It uses no compressed
gases, no tubing, no compressors. It is essentially a big semiconductor
slab that heats on one side and cools on the other (as I understand it --
I hope I'm not too far off) as you pass current through it.
As to the point made in bringing 100+ Amps to the place where cooling
is needed, here's two alternatives:
1) how about converting 12V to high voltage A/C and moving it around?
(still not too clean -- would not require thick wires, but
would be quite 'shocking' if anyone were to touch bared wires)
2) how about moving the coolinfg unit next to the Alternator (I imagine
would have to be a BIG one) and forcing the cool air into
the passenger area?
Thanks for the discussion -- this is getting to be fun...
Cetin Seren
cs@karin.att.com
