sponsan (Newbee)
11-26-02 03:21
No 383351
      kryotech PC cooler unit as generic lab cooler  Bookmark   


Is it feasable to use one of these units as an immersion cooler device:

I think they can be picked up for cheap nowdays.
(Hive Bee)
11-26-02 21:20
No 383622
      Yes you can use them, but you will probably be ...  Bookmark   

Yes you can use them, but you will probably be dissapointed unless you invest some real effort into controll and additional heat ejection.  They usually come out of the box with a fan for forced air cooling directly applied to the "hot" side of the Peltier chip(the active component). 

Unfortunatly forced air is a relatively poor option for heat ejection and will rarely carry away all the heat pumped accross the chip.  The device does not operate with perfect efficiency, as you might guess, meaning it adds heat to the heat being pulled from the material being cooled.  So you have to eject plenty of heat, or the heat will build up on the hot side which in turn affects the temperature on the cold side.

Control becomes important when you consider the following scenario...

Current Level X is the amount of current needed for a balanced system

   heat pumped + waste heat = ejected heat

Then X + K

   heat pumped + waste heat > ejected heat  (heat buildup)

If you have a simple temp controller in place, it would respond by increasing the current supplied to the chip adding to the waste heat and further heat buildup... etc.  Until the chip melts down.

I could never get a reasonabl result from peltiers without cooling the peltier by liquid coolant and monitoring the temperature of both sides of the device and inteligently adjusting the current dynamically every second or so. 

If you do this you get the most wonderfull cooling controller ever, and when you cool the peltier using a MeOH/ice coolant, the Peltier can cool the target to maybe 40deg C BELOW the temp of the MeOH/ice solution which is way fucking cold.  So it can hit low temps, and is very affective in targeting a specific temperature and holding it against determined exothermic reactions.  But complicated and frustrating to build, for sure.


PS.  I started a writeup of a pc controlled circuite and contruction details for the necessary cooling system, but lack of real interest pushed it down the priority list for the moment.  But I am very close to completing a much easier cooler setup capable of automated temp control and capable of condensing NH3 no problem.  But it requires a few pounds of dryice to achieve the very lowest temps.

And on the eight day, God created Meth...
... and hasn't done much of anything usefull since!