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Peltier cell questions

  • Thread starter lithopsman
  • Start date
  • #21
How soon are you building this?

If its going to be a few weeks, I can try to do an experiment for you. I have the watercooling system here, but I need to get another HS/F and a pelt.

About the ground. A lot of people will pull the 3rd prong out of a plug to fit it in a 2 prong timer (the cheap kind) DO NOT DO THIS WITH A POWERSUPPLY AND PELTS!! Basically, if there is a short, instead of catching fire, the electricity gets sent back to the plub and it trips a breaker. Pelts draw as much power as the power supply can possibly give it, which in turn heats the power supply up, and with a cheap power supply in very rare cases it can melt the wires and short out (not a problem if its grounded)

Same thing with your lights, especially if you have them inside your terrarium, they should be grounded.

I did actually use the cheap timers and pull the grounds off my surge protecter to use it, but I spliced the 2 grounds together and hooked em to a bare plug so its still grounded to the house. (I didn't check the timer, and didnt feel like going back to home depot)


Casper
 
  • #22
Ok, thanks for the offer, but I plan on doing this sooner... Anyways, what is the power supply only comes with 2 prongs? I guess I could find one with three... Also, since I only plan on running this 30 mins to an hour at a time, and all of my (many) electronics (both current and upcoming) are and still will be hooked up to a 6-way surge protector, which I was under the impression was the same thing as a master grounding system for everything plugged into it... (which is a lot, currently 5 or six, but will be 9 or 10... At least we have breakers for every individual outlet, and they are on a surge protector... BTW, the most things actually running at once will be onl 5 or six, not counting the opposite timer turning on/off the other things that will then be off. So basically, I'm not to worried about it, because my current setup has endured many a hail storm and tornado (read power outage) no problem... Any more suggestions? THANKS A MILLION BAZILLION QUADRILLION!! P.S. I am just going to try what is mentioned in Figure 2, and see if it works, hopefully well enough for a 15-25*F drop... Thanks again!!
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  • #23
Well, here's an update:
Today or tomorrow I will order two peltiers and two heatsinks (unless anyone thinks that it is ultra-neccessary to have three...) Than, after I get power supply, thermal grease, etc., I will do some experimenting on positioning of peltiers, fan, etc, and I am hoping that I can get the results that I am looking for out of two peltiers, if not, I will order a third... Any last suggestions? Thanks for all of your help thus far!!
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P.S. I will update you again once I setup, experiment, etc... I hope that this will:
A. Make more people find it easier to cool highlanders(including me)
B. Help you setup one of these setups for yourself.
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  • #24
I just have two things to comment:

1) Peltiers are much less efficient than compressors (ie conventional refrigerators)

2) The setup with water cooling, etc is cool, but an old chest freezer modified as described in an earlier issue of ICPS Carnivorous Plant Newsletter will probably be easier, cheaper and work better ... and be much cheaper to operate (better insulated, better efficiency).
 
  • #25
Whats the point of growing plants in a deepfreezer? You can't look at them or display them at all. Isn't the whole point of growing beutifull plants to display them and let them be seen?

Just one mans opinion.

Btw: Nothing is more efficiant than a pelt. It converts electricity directly into tempeture change. With the right equipment a 2" plate can bring 300gph of water very close to freezing (disapaiting something like 200W) Chestfreezer is probably easier and cleaner though, but where is the fun in that? Plus, you have to find on for cheap. #### of an idea though, do you have that newsletter in .pdf or something you could send me?


Casper
 
  • #26
I don't think that I am water cooling, I probably will do two pelts, with heatsink on top, and a homemade aluminum coldsink on the bottom, with another CPU fan that blows the cold air off of the coldsink and down towards the plants. Thanks for all the suggestions, I'll keep you updated!!  
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  • #27
potential problem:

Ice formation and defrosting cycles.

Ice cold water/ice dripping/falling off will damage the plants if it hits them (I think).
Tony
 
  • #28
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Casper @ Sep. 25 2003,08:44)</td></tr><tr><td id="QUOTE">Btw: Nothing is more efficiant than a pelt. It converts electricity directly into tempeture change. With the right equipment a 2" plate can bring 300gph of water very close to freezing (disapaiting something like 200W) Chestfreezer is probably easier and cleaner though, but where is the fun in that? Plus, you have to find on for cheap. #### of an idea though, do you have that newsletter in .pdf or something you could send me?[/QUOTE]<span id='postcolor'>
Sorry to disagree with you, but thermoelectric junctions have not yet approached conventional mechanical compressor systems in efficiency. There is a new technology that may be reaching market now that is closer than was theoretically possible about ten years ago, but it still falls a long way short. I read the article on it with interest, though, because there are obvious advantages to thermoelectric junctions.

I'm not saying they can't cool things a lot, just that the efficiency (power consumption) is poor. That's what is going to count in the long run, just like with lighting options: the energy costs.

The ICPS newsletter is probably not available in PDF... (Barry, are we ever going to have that option?) i think the subscription rate would probably decline if it was.

The basic idea was to take the top off of a chest freezer, and use a sheet of glass to cover it. Great way to grow ultrahighlands, but yeah, probably a bad way to see them.
 
  • #29
Hi Tony, thanks for the suggestion!! I plan to put these near the back, and I will allow an area underneath them for the ice/water to fall. THANKS AGAIN, I ordered last night!!
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  • #30
Hey lithopsman! I was just wonder how your system is working.

I saw a peltier cell for sale at a science surplus store on the internet while I was looking for some small computer fans to cool my fluorescent lights above my terrarium. I have 6 tubes and they really seem to put out a lot of heat. I put the sensor of a digital thermometer between the tubes and the glass top of the terrarium and it said it was 116.1 degrees!! Inside the terrarium it is usually around 85-90 when the lights are on and around 70 when they're not. I’m hoping a couple of fans will help cool the tubes since the excess heat seems to shorten the life of the bulbs.

Ok anyhow, about the peltier again. I thought they sounded pretty cool so i bought one on ebay since it was cheaper. I didn't really buy it to use for cooling my terrarium though. Basically I bought it because I wanted to play around with it. After buying it I remembered seeing some posts about them here on the forums that I never really read. So I did a search and that’s when I found this post. And it made me wonder if I could use it to help cool my terrarium too.

-buckeye
 
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