Author Topic: Build your own refrig. recirculator!No more ice.  (Read 2046 times)

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Triton

  • Guest
What's wrong with immersion coolers?
« Reply #20 on: October 31, 2002, 06:40:00 AM »
Would'nt it be much easier and safer to just use an immersion cooler instead of messing around with CO2 and all thats required to use it?
Used ones aren't very expensive at all.

goiterjoe

  • Guest
thermocouples are cheap
« Reply #21 on: October 31, 2002, 07:25:00 AM »
It's easy to attach a thermocouple to each side of the peltier device to get temperature readings to use for closed loop feedback control.  PWM modulation would be a lot easier than PAM, since you could just use relaying circuits to regulate temperature instead of having to use amplifying circuits.  You could pick up a programmable controller board for under $100 to automate your cooling device; this would also make the setup extremely portable.  You could write different programs to load onto the controller board for different setups and reactions.

I've started a couple of threads on peltier devices in the past.  If you're going to open a thread on them, we ought to talk about everything from power relaying to PID controllers.  That way we can talk about the complete electrical design of the system.

If at first you don't succeed, try, try again. Then give up. There's no use being a fool about it.

Rhodium

  • Guest
Yes please, this was hugely interesting.
« Reply #22 on: October 31, 2002, 07:43:00 AM »
Yes please, this was hugely interesting.

jimwig

  • Guest
lets see if the ambient coolant temperature is ...
« Reply #23 on: November 01, 2002, 07:18:00 PM »
lets see if the ambient coolant temperature is 20C
and the high side of returned coolant is 100C
the required ideal drop (high efficiency) would be -80C
that's a lot --especially for continuous use

though it is a small volume and a small area-- hmmm?

can a peltier or a series of peltiers be counted on for that sort of use?

two conventional compressors such as in lab freezers (the minus zero variety) seems more likely - hooked up in series so as to have an intial drop on one and then a secondary drop to the desired level on two.


jimwig

  • Guest
ya know the volumes here are really the problem.
« Reply #24 on: November 01, 2002, 07:27:00 PM »
ya know the volumes here are really the problem.
i mean if you have say a ten thousand gallon coolant tank and you are lowering the temp 80C at a flow rate of 2gmp then you are considerably along the way.

i don't have a lake handy and using that kind of flow would make me feel wasteful. recirculation and cooling has always been the desired method.

something along the way of a precooler before return to the coolant pool and then letting the adsorptive recycling coils be submerged in the vast ==== nevermind.

i still really like the solar ammonia collector. its just a fantasy but who knows....

TrickEMethod

  • Guest
I am not entirely sure I understand you ...
« Reply #25 on: November 03, 2002, 06:46:00 AM »
I am not entirely sure I understand you statments/questions.  But on a hunch, let me offer some comments...

If you are trying to 'drive' a condenser, you have to do two things.

1) Have enough heat ejection capacity to keep pace with the 'load' caused by: 

  a) vapor condensation
  b) super-cooling of the condensate before it exits the condenser
  c) heat exchange with the surounding environment

2) Deliver accurate temperature control through real-time current adjustment based on sensor feedback from the system.

I like the strategy of using a secondary coolant reservior filled with anything from water at room temp to MeOH/ice at -20deg Celcius to deliver the real heavy lifting and use the Peltier as more of a controling device or when necessary, range booster.

Depending on a Peltier to deliver a 30deg Celcius temp drop is practical, anything greater is most likely going to require multiple stages.  And even with multiple stages, going above 45deg Celcius is pretty tough.

This means that a Peltier only system working from Ambient (22 deg Celcius) might get you down to -20 or so.  And achieving this will absolutly require a liquid-air heat exchanger.  You just can't get enough heat ejection from forced air heat-sink dissipation from a 1.5" x 1.5" surface coupling. 

Believe me.  I tried, and tried, and tried... and never even got 10% of what I needed.  If you arn't willing to back a Peltier with a surface/liquid exchanger, pump and secondary coolant, then you should not bother with the device.  It's just took fucking lightweight without it.

TrickE

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