Peltier Cooler - Page 3

Rain_Frog · #21 (**permalink**) 01-13-2006, 04:59 PM

Yes, I have seen those, but they all look pretty large and i don't really need the "food warmer" unless I want to keep some baby crickets or something. Most I've seen are in the $50-70 range, whereas the beer cooler (according to hackaday) is only about $35. (but a few other parts like a powerhead are not included)

I'll reconsider, but the design for the beer cooler is a bit more compact.
Perhaps Ed knows what the ceramic is made out of?

Just one thing...how do I wire the temp controller and adjust it? I don't know much about electronics except how to wire ballasts to CF, etc.

Now. What SIZE peltier do I need? I'm going to start with that new tinctorius vivarium. I want to cool water about 4-6 degrees. There will be around 1-2 gallons in the sump. The water will be piped up down a drip wall to spread it out and act like a nice heatsink.

Ed · #22 (**permalink**) 01-13-2006, 05:21 PM

The come in sizes as small as 5 liter (1.32 gallons) (see http://www.cooler-store.com/vector_ther ... 6_prd1.htm for an example). I suspect that the difference between the cooling and the warming function is simply the result of the air circulation via the sides of the peltier as this allow for the warming and cooling.

I'm not sure what ceramic you are referring to as I didn't see it on the web page.

Ed

Rain_Frog · #23 (**permalink**) 01-14-2006, 05:33 AM

Assuming if we make our own cooler from scratch, the peltier's cold side is ceramic, but I know the device itself is made from bismuth telluride. (is it?) I'm not sure if the ceramic cold side or the other parts of the peltier are 100% safe for coming into contact with vivarium water (corrosion, damage to the device, leaching of trace elements like the bismuth telluride, etc...considering vivarium water is acidic and rather hard).

Well, one could point out that the design anyway has the peltier elevated to cool the small amount of air in the box first above the water, but condensation and ice formation will certainly allow stuff to drip into the water system (so, distilled water from condensation. If this were aluminum for example, distilled water/ RO will corrode it).

Most peltier coolers were designed to where they cool contained beverages, not directly to where anything could drip onto food/ water.

Problem with the these coleman coolers. They mount the peltiers on the side, not the top like in the diy model by Hackaday. Wouldn't that reduce the water level in my sump? (basically, to nothing)

Ed · #24 (**permalink**) 01-14-2006, 01:29 PM

I don't know as I haven't actually had the chance to mess with one yet, my knowledge of them came from an old post from the ICPS listserve. There were too variations on this (if I am remembering corrctly), one a guy used a large one to house highland Nepenthes and and another guy dismounted it from the cooler and mounted it on his Edwardian Case for highland Nepenthes. The reason they did this was because these units have thermostates already included and werer already wired up and this allowed for a little more control of the temperatures as opposed to wiring them in from scratch. (Also you can readily buy converters allowing them to be plugged into the wall).

With the coolers, even if they are mounted on the side, you could remove the aluminum liner, and line the thing with acrylic which could be attached directly to the plastic liner with acrylic glue and then build a wall to prevent the water from contacting the chiller or use a larger one and just drop a smaller tank into it as a resivoir and plumb through the top.
With the coolers as these are made to control the temps in an enclosed space there should be something in there to deal with the condenstation from humidity and either prevent it from contacting the chiller or to wick it away.

There is a guy on caudata who just mounted it vertically inside his tank
see http://www.caudata.org/forum/messages/7 ... 1123636262

Here is another alternative using a room dehumidifier as the chiller.

http://www.fnzas.org.nz/fishroom/2-vt6927.html?start=15
Ed

Rain_Frog · #25 (**permalink**) 01-14-2006, 06:42 PM

Yes, I read both of those. I made a chiller from a dehumidifier (for the clawed frog tank, 100 gallon), but that is way too large for such a small application in this case.

I find the way the guy mounts the iceprobe directly into the tank to be very dangerous. All it takes is that to fall into the tank or a frog to jump ontop of the fan...and well...

I'm trying to avoid buying an iceprobe, not worth the cost unless you buy a used one.

You sure weldon will bond to that type of plastic in coolers or shoeboxes? It works great with acrylic, but it won't adhere to every type of plastic though. I'll do a test on a shoebox to see if it melts it (it will melt/weld plastic dixie cups though).

Rain_Frog · #26 (**permalink**) 01-19-2006, 07:08 PM

Some of the Ti on ebay is 8% magnesium. Will magnesium degrade the properties of Titanium?

defaced · #27 (**permalink**) 01-19-2006, 08:33 PM

Well that depends on what property on the Ti you're interested in. The magnesium is added for a reason; what reason I'm not sure though. Since you're interested in Ti's thermal conductivity property, it's going to make very little difference. I do know that Ti-6-4 is the most commonly used grade of Ti, and the same grade that's used for implants, so it's definately safe. As for the magnesium alloy, I'm not sure; I'd need more info, specifically what else is in the alloy.

Rain_Frog · #28 (**permalink**) 01-20-2006, 02:43 AM

http://cgi.ebay.com/Titanium-Sheet-TI-M ... dZViewItem

Its the same Ti you and I both saw on Ebay. I believe it has been used for air crafts?

Rain_Frog · #29 (**permalink**) 01-20-2006, 02:49 AM

http://www.smallparts.com/products/desc ... s/smti.cfm

this is the original place I looked into. It is 99% titanium alloy, and not much more expensive for the thinnest sheet. How strong is .035" Mike?

BTW, did you get my PM?

defaced · #30 (**permalink**) 01-20-2006, 03:24 AM

Yea I got your PM. I must have accidently unchecked the option to have me notified by email if I have a PM because there were a few waiting on me. I'll get back to you on it. Hopefully tonight, if not then tomorrow night.

.035 is pretty thin. That's about 1/32 of an inch. I'd personally go with something thicker because it's easier to work with, harder to bend. The .065 is just a tiny bit bigger than 1/16", that's what I'd go with.

The CP Ti you linked to on small parts is fine. It's what's used as a base for Ti alloys. The Ti-Mg alloy on eBay is something special. I can't find any information on it. That's even checking Cambridge's online data base of phase diagrams clicky. How much is Ti-6-4 (6% Aluminum, 4% Vanadium)?