that's what I said
a single Peltier running using 72W of electricity (common size) will
dissipate at a maximum 144 watts of heat from the hot side. 72 watts from
the power in then 72 watts pumped from cold to hot side, as far as I am
aware.

so if you want to stack them and get optimum cooling you need to have them
pyramid style. 1x on the first layer, 2x on the 2nd, 4x on the 3rd etc etc.
the thermal design for such a setup is left as an exercise for the reader.


> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Oyvind Tjervaag
> Sent: Saturday, 17 January 2004 1:36 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE:] About test boxes (hot and cold)
>
>
> On Fri, 2004-01-16 at 13:53, Jake Anderson wrote:
> > a peltier will shoot for roughly 65C temperature difference hot
> side to cold
> > side.
> >
> > A peltier that pumps 72W of heat will also produce 72W of heat
> (IE 144 watts
> > must be disipated from the hot side)
>
> Actually I believe (or I might be very wrong...) a peltier will produce
> more power than it is pumping from the cold side due to heat also being
> produced internally in the plate.
>
> I did a project once where I cooled a metal plate to about -25C it took
> 3 stacked peltiers to get that low. The most tricky part was to actually
> 'tune' the three plates (in terms of current and voltage) to get them to
> work the best. I only used air cooling at the hot side for this
> application. Using water would probably lower that temerature
> significantly. Remember to get silicon sealed units if used for cooling.
> Water could kill them quickly...
>
> One place tor more information: http://www.melcor.com/handbook.htm
>
> Xyvind
>
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