This would work as a chiller

My mom has this for her knee, but It would work great if you order an extra large pad and just set in in the bottom of the tank, in shallow water.

http://www.breg.com/products/cold_therapy/polar_care_300/default.html

It looks as if it would work well Jeff. I am betting that those units are fairly expensive however (I didn't see a price).
Chip

interesting... quick google search this site http://bracesupport.com/breg/polar.htm that unit cost about $160 alone and the pad are extra. also searched ebay and there are some used units available.

you could possibly make your own too with the pad, a picnic cooler, and pump

The issue with this is similar to all other methods of ice-cooling: You have to keep the cooler filled with cold water/ice/whatnot. Although it says along the lines of providing 6-8 hours of cooling, it's definitely not made to cool water, so I don't know if that time frame would accurately reflect on water cooling.

Also, can you actually submerge the parts? I don't know how 'waterproof' the pads would be.

(Message edited by Joan on April 09, 2007)

I would tend to assume the pads are just filled with tubing and are essentially a heat exchanger thus they should be fairly waterproof. While not the optimum configuration, you could use it as undertank cooling rather than submersing the heat exchanger. Given that this item is intended to cool a part of the human body from 98F I think it would do a fine job of cooling a small tank of water or providing a nice temperature gradient in a larger tank of water.

I will however second the concern about it requiring ice. That's just a pain in rear. The price isn't too bad but I think for that amount you could rig up your own possibly superior cooling system using a dorm fridge, pump, and tubing.

Since I have the luxury of having a dedicated herp room, I don't worry too much about cooling.

But I wonder if you could take a mini-fridge (not too mini) and put a fairly powerful air pump inside the fridge. Then take tubing and coil it inside the fridge (for additional cooling, I suppose) and then run the cooled air through airstones (perhaps multiples, to reduce the 'disturbance). With a piece of styrofoam or other insulation on the top of the tank, you should be able to keep most of the cool air in.

My thoughts are that once the tank is cooled, the cool air should keep it fairly steady.

It seems most people want to just run the tubing through the fridge. But I don't think anyone's mentioned putting the actual pump in the fridge as well. Any thoughts?

Kaysie, like you, I don't need any cooling systems because I have a nice basement. But, I thought I should point some things out just in case someone wanted to try this.

Air is terrible working fluid because it's specific heat is so very low. To illustrate this, I did a quick back of the envelope calculation:

Assume: 10 gal of water to cool from 80F to 70F
Tank is PERFECTLY insulated from surroundings (no heat gain)
Air lines are PERFECTLY insulated on the run from fridge to tank (no temperature rise)
Air is supplied at 30F at a rate of 0.35 CFM (per Air Pump AP2 model at maximum operation - note: could be better pumps out there!!)

Total energy to reject to achieve 10F drop - 355kJ
Using thermophysical properties of air at 350K gives a required volume of 30F air of 9m^3 to cool the water. The referenced air pump would require 15 hours to supply that much air!! I can supply all details of the calculation if you'd like to see it.

Now, in reality, the tank is transferring energy with the surroundings during the process and thus the actual time will be MUCH longer! I didn't research air pumps very much so there may be better performing ones out there but I don't think you're going to find one in a decent price range that can move the volume of air needed to cool water in a reasonable time frame.

Now, you may point out that I'm talking about the transient cooling event where you state if you can get it that cool, the air will maintain it. The cooling rate on the air system detailed above works out to be right at 5W. We would have to make some wild guesses about someone's environment to tell if the system could actually hold it at the required temperature but my gut feeling is that most people who are looking into cooling systems will have a higher environmental load than 5W.

My advise as a thermal engineer is to not bother messing with forced chilled air for cooling water. Air is useful for cooling in the following situations only:
a)evaporative cooling
b)cooling things that are VERY hot
c)cooling things that are VERY small
d)when you can move massive amounts of air (like the system in our homes)

If I'm going to rig up a cooling system based around a mini-fridge, I'm going to use a closed water loop.

John, I have to say that is incredibly nerdy. lol.

Thats pretty cruel kaysie.I think its a neat idea. Let us know how it turns out John.

A setup I used to have for taricha, was a gravel and water river like setup, using a pump at one end and flowing the water around the tank like a stream. The water wasn't that deep, and I used to just put flexible ice packs in the middle, and the newts would go lay on them. I was thinking something like that that would last for 8 hours or so would be perfect.

It would also be possible to run 15 feet of 1/4 inch tubing back and forth along the entire bottom of the tank and pump water through a mini-fridge where the powerhead in submerged in a bucket of icewater in the fridge. That should give the newts a good 5-7 degree drop for most of the day.

Richard, it was not a 'cruel' intention. Nerds are awesome, and the fact that he would take the time to actually figure out the cooling is nerdy to the extreme. Awesomely nerdy. Hence the LOL on the end.

I know you were just joking Kaysie. Im sorry if I offended you. I meant to include a smiley in that sentence but I guess I forgot .

Rich

BTW Im glad you think nerds are awesome as I guess Im one myself!

No harm.

Yeah, friends of mine often joke of how incredibly dorky I am. It's especially bad when watching animal-based movies. "That would never happen!" "But turtles can't get out of their shell!" etc. My niece and nephew hate it.

LOL!! I'm a total nerd Definitely no offense taken!! Cooling things is what i do for a living so it's second nature to me. I can run through those calcs pretty quickly. Looking up the material properties takes longer than the actual calculations.

As far as people's cooling woes go, as I've said before, the first thing to do is to characterize your spaces. You'll probably be able to find a location in your home that runs several degrees cooler than anywhere else or that has less diurnal fluctuation. Unless this location is just silly, like in a cabinet, then that's where you should place your tank(s). Just doing this will help a good number of people who aren't breeding caudates, you can find something that's "good enough". The next easiest is to use evaporative cooling with a fan. That's great for people who are really attentive of their animals water quality. However, for people like me who tend not to monitor that too well, evaporative cooling can cause problems. So, next after evaporative would be something like the pumped loop. People have brought up TECs before but cheaper ones don't have a very favorable delta T and they also only provide several watts of cooling. What we really need to cool decent sized volumes of water is something like 20+W of cooling. Of course...If you want to get really cool, you can always rip the vapor loop off the mini-fridge and re-route the evaporator section to use it as undertank cooling!! Actually, that could wind up easier to implement than the water loop cooled by the mini-fridge!!