Re: High tech gadget?

["S. Hieber" <shieber at yahoo_com>]

Bill Wichers, giving some good info on solid state thermoelectric
devices said, in part:

<billw at waveform_net>
> Subject: Re: High tech gadget?
> 
> As someone that has played with these (not for aquariums, but the
> same
> technology), there are a few things I thought I should mention.
>  
> >not require plumbing (other than drilling the holes for the bulkhead
> 
> >fittings), and they are relatively energy efficient compared to a 
> >compressor.  Goeman did state that the IceProbe would cool a 
> >"fully-insulated" 10 gallon tank 20 degrees F below ambient, so the
> actual 
> >performance of the unit can be tweaked some.
> 
> They are not as efficient as you might think. . . 
> What you need to know is that peltier junctions generate a *LOT* of
> heat
> themselves in the process of moving heat. The units are only 50%
> efficient . . .

Well 50% is pretty darn good for a cooling device or almost any device,
with a few exceptions, of course.  I would guess that the effective
efficiency of a dvice using these chips would be less than the 50% --
there would be additional input for the fan, for example, and an
elecric motor would be lucky to have 30% efficiency, would it not?

> . . .All that heat then must
> be
> dissipated in a very small area RIGHT NEXT TO the COLD SIDE. You
> can't have
> a large seperation between the hot and cold areas like you can with a
> freon-based chiller.

That's an important point.  Unless you have a remote sump or inline
device, you are going to dump the heat right into the same room as the
tank and the chiller will be in the same room.  But these are much
quieter than the compressors on conventional chillers -- with the solid
state devices, you have the fan noise only.

 
> Freon-type chillers will be a better (and certainly more economical)
> way to
> achieve a large cooling capacity. I don't think you'd be able to get
> enough
> peltier-based chillers in your tank to match the cooling capacity of
> a
> small freon chiller. . . 

Most of the commercial models I have seen, although not intended
origianlly for aquarium use, were in the range of a few hundred to just
a few thousand BTUs/hr. of cooling capacity.  But conventional chillers
are pretty big -- if you put the water against the peltiers at a remote
location (i.e., not in the aquarium), as is done with most conventional
chillers, then the size issue isn't so important.  The price should get
cheaper provide the market for them grows, chloroflorocarbon gases
don't keep rising steeply in price (which would increase demand for
alternative chillers), and peltier chip mass production methods
improve.

> . . .The peltier units are excellent for portable
> applications like transporting sensitive fish in a bucket though,
> especially considering that most can run on the 13-14 volts DC in
> your car.

Now, besides my house and office, I can have an aquarium in my car! 
All I need is a way to explain the sense of this to my family ;-|


Stay cool,
Scott H.

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