Cheap, Thermo-Electric coolers...

So I was reading through a sports-outfitting catalog, and I found a product that seemed like it was begging to be applied to tank cooling. They are designed to plug into a 12V DC car battery but if one were savvy it could probably be hooked into a standard wall socket. It's basically a car-cooler with built in refrigeration/or heating for drinks and such... they claim to be able to lower temperatures in the cooler compartment by 40 degrees (below ambient temperature)... They range in price from $40 to $120 depending on the capacity.

I'm not sure how they are built because I haven't looked at one in person but this seems like a viable alternative to piping water through a mini fridge, if you could engineer it.

I originally was looking at them as way to transport caudate specimens from the field on long road trips but started thinking about other applications.

just do a web search for Thermoelectric car coolers.

The efficiency of Peltier/Thermoelectric Effect coolers are limited in aquaria application. To get truly effective liquid cooling from one, it is advisable to have a separate heat exchanger circuit for the hot side plate also. This is the catch of the Peltier Effect. The procees works better for cooling gases rather than liquids.

Without getting into the engineering math, (which even that horrid source Wikipedia has available) the "cold" side of the plate actually absorbs heat energy when a current is applied; the hot side of the plate radiates this heat plus the heat from the electric circuit. To be trully efficient, the heat must be removed from the hot side as fast as possible and the cold side must be protected from humidity. The cold side often reaches sub zero surface temperatures which forms frost on the surface and interferes with the heat energy absorption process.

In the case of most freshwater animals, amphibians especially, copper becomes an issue. Since the most efficient affordable ones are made of it. Use of aquarium tubing fails invariably and results in a thermal runaway effect since the plastics are such poor thermal conductors. Since closed loop systems are filled with ethylene glycol mixes as thermal transfer media, the risk of critter fatal leaks is high. Open loop direct cooling loops can be done, however the water will freeze in the lines after only a few minutes of continuous operation.

I have seen Peltier/Thermoelectric cooling systems for computer CPUs succesfully converted to aquarium use. These systems utilized custom made aluminum billet heat sinks, however temperature drops no higher than 3 degrees were achieved in a standard US ten gallon aquarium. The catch here is the cost, which makes it actually cheaper to purchase an off the shelf aquarium chiller instead. Frozen water issues were solved by a timer and intermittent operation.

(many thanks to a certain defense company I worked for years ago and our attempts there at Peltier Cooled RADAR)

good to know, before I buy one and cut her open....

I've made a few thermoelectric cooling units for terrariums in the past, mostly from tearing apart the Igloo ones (which I think they've discontinued). They don't work very well for water, but work ok for air cooling. The key is that you have to insulate the tank like crazy. I used three of the largest units for a 65g tank insulated on 4 sides and could get the temp down into the 50s, but it was pretty darn expensive (few hundred $) to make. I attached a couple of photos. It probably has some application to terrestrial salamander keeping, and probably cheaper than cooling an entire room if you have a single tank.

The one unit I still use regularly is a modified cooler with a temp controller that I take into the field when collecting salamanders. Works great on the road or in hotel rooms, since you can run it off cigarette lighter or a 120V outlet with the adapter.

-Tim

Hi Taherman and folks,

seeking your experience and advice.

i currently have a resun 450 2nd hand chiller which i used to chill to 22*C for my P.chineses tank.
but i do not have an idea to "split" my resun 450 chiller to chill 2 tanks?
if there's a way to "split" the chiller to chill 2 tanks, will the water from P.chineses be toxic to Axotlos or vice versa?

therefore i was thinking of buying a cheap TEM chiller $80-$100 for my axotlos tank.
my axotlos tank is about 28L 2FT 15cm water.
water temperature is about 25-26*C without chiller.
do worry i haven't got the Axotols yet.

i just do not know if these cheap TEM chillers can chill from 26*C to 22*C?
will a combination for 2*12cm top mounted fans be possible (evaporation cooling)?

here's the TEM chiller dolphin MC788 i am looking at

http://www.absolutereef.com/forums/index.php?showtopic=11044&pid=163306&mode=threaded&show=&st=&


thanks and have a nice day

taherman said:

I've made a few thermoelectric cooling units for terrariums in the past, mostly from tearing apart the Igloo ones (which I think they've discontinued). They don't work very well for water, but work ok for air cooling. The key is that you have to insulate the tank like crazy. I used three of the largest units for a 65g tank insulated on 4 sides and could get the temp down into the 50s, but it was pretty darn expensive (few hundred $) to make. I attached a couple of photos. It probably has some application to terrestrial salamander keeping, and probably cheaper than cooling an entire room if you have a single tank.

The one unit I still use regularly is a modified cooler with a temp controller that I take into the field when collecting salamanders. Works great on the road or in hotel rooms, since you can run it off cigarette lighter or a 120V outlet with the adapter.

-Tim

Click to expand...

Hi,

The most important information for figuring out if it will work is the volume of water in the axolotl tank, and the power of the Dolphin MC788 chiller. In my experience the IceProbe chillers do not work very well on volumes of water larger than a few gallons. If this chiller is of similar power it probably would not work.

-Tim

You could probably split the chiller to work with a little creative piping and an auxiliary pump, however I would advise against it for two reasons:
1. sharing water between two tanks with two different species is a bad idea. (newt toxins and disease can spread this way)
2. As Tim stated, this will significantly decrease the total cooling value as the overall volume of water increases

So for a small tank or sweaterbox set up, this does seem like a viable and relatively inexpensive cooling system. Perhaps not in the way I had thought, but good to know...

taherman and sludgemonkey, excellent and expert imput as always. Thanks.

hi taherman,

i have checked the specs.
my tank is 28-30 liters
my room temperature 28*C
water temperature without any cooling is 25-26*C

the power of the Dolphin MC788 chiller is 75watts
will it be able to cool to 22*C ?

Thanks

taherman said:

Hi,

The most important information for figuring out if it will work is the volume of water in the axolotl tank, and the power of the Dolphin MC788 chiller. In my experience the IceProbe chillers do not work very well on volumes of water larger than a few gallons. If this chiller is of similar power it probably would not work.

-Tim

Click to expand...

ksc133 said:

hi taherman,

i have checked the specs.
my tank is 28-30 liters
my room temperature 28*C
water temperature without any cooling is 25-26*C

the power of the Dolphin MC788 chiller is 75watts
will it be able to cool to 22*C ?

Thanks

Click to expand...

(I'll jump in here again on this one...)

Here is the math that can be done to calculate the cooling power. It is actually pretty simple.
Keep in mind I am not sure of the metric formulas, so I will do it in US measurement and then convert the results.


about 10 Btus is needed to raise/lower 1 pound of water 1 degree

1 Watt is 3.41 Btu/hour

So we need about 34.1 watts per gallon to drop the water temp 1 degree

I will estimate your tank values to these for the formulas:

8 US gallons @ 82°F, MC788 chiller is 75watts or 255.75 Btus/hour

So knowing all this we know that theoretically that chiller can drop 7.5°F per hour in perfect conditions at a full 75 watts

In reality. it is probably more like 5°F per hour if you figure in evaporation, ambient air temp, surface area, and a ton of other factors.


So, your roughly 30 liters of water in the tank can be cooled to around 22°C in about 2 hours of the chiller running on full power. As long as the air temperature does not go over 30 °C you can easily use this chiller to cool this small tank and maintain this temperature. When you estimate in evaporation through a screen cover on the tank, you can very easily keep that temp over time.

Looking at the math this chiller would be suitable for cooling up to a 75 liter long tank with out issue as long as the air temperature does not go over 30°C for long periods of time. It does not have the power to handle larger volumes of water efficiently.

taherman said:

I've made a few thermoelectric cooling units for terrariums in the past, mostly from tearing apart the Igloo ones (which I think they've discontinued). They don't work very well for water, but work ok for air cooling. The key is that you have to insulate the tank like crazy. I used three of the largest units for a 65g tank insulated on 4 sides and could get the temp down into the 50s, but it was pretty darn expensive (few hundred $) to make. I attached a couple of photos. It probably has some application to terrestrial salamander keeping, and probably cheaper than cooling an entire room if you have a single tank.

The one unit I still use regularly is a modified cooler with a temp controller that I take into the field when collecting salamanders. Works great on the road or in hotel rooms, since you can run it off cigarette lighter or a 120V outlet with the adapter.

-Tim

Click to expand...

Hi,
i may have missed this in the thread but what was the temp in the tank before you build this chiller systeme? you get down to 50F from? if you have a tank temp at say 68 can you then lower that to 50f? or from 77-59 and so on,, have i misunderstand?

Nice tank by the way!
Regards.

Don't have a lot of time to reply right now, but I want to say the room temp was roughly 75F and the temp got down to 55F. Each of those units was at least 50W, if not 70W, for a total of between 150-210W of cooling.

The problem with the calculations listed above is that they do not factor in the rate of heat gain from the room. If a tank of water at 22C warms by 1 degree every 15 minutes in a warmer room you have to factor that into the cooling power necessary. I totally made up those numbers but you get the idea This rate of heat gain is buffered if you can insulate the tank, which is what I did in my case.

HTH
Tim

taherman said:

Don't have a lot of time to reply right now, but I want to say the room temp was roughly 75F and the temp got down to 55F. Each of those units was at least 50W, if not 70W, for a total of between 150-210W of cooling.

The problem with the calculations listed above is that they do not factor in the rate of heat gain from the room. If a tank of water at 22C warms by 1 degree every 15 minutes in a warmer room you have to factor that into the cooling power necessary. I totally made up those numbers but you get the idea This rate of heat gain is buffered if you can insulate the tank, which is what I did in my case.

HTH
Tim

Click to expand...

Correct! As stated, that is just the raw numbers, there are quite a few outside the tank factors that are not figured in. Ambient thermal transference, evaporation, relative humidity, and water volume are all variables that would figure in to the "final" estimation. Didn't want to nuke it...

taherman said:

Don't have a lot of time to reply right now, but I want to say the room temp was roughly 75F and the temp got down to 55F. Each of those units was at least 50W, if not 70W, for a total of between 150-210W of cooling.

The problem with the calculations listed above is that they do not factor in the rate of heat gain from the room. If a tank of water at 22C warms by 1 degree every 15 minutes in a warmer room you have to factor that into the cooling power necessary. I totally made up those numbers but you get the idea This rate of heat gain is buffered if you can insulate the tank, which is what I did in my case.

HTH
Tim

Click to expand...

I think i understand what you mean here, the total lower of the temp is around 50F in your tank, and if the tank air tempt gets 39Fwarmer then the cooling advice wount be able to lower it futher? temp will raise as the room gets warmer..stupid swed? = )

A question taherman.

Do you have a link to the cooler you have used here? i have two myself (picknick coolers) but not with that much capacity.

hi folks

look at this to believe it

http://www.metacafe.com/watch/1986696/diy_peltier_portable_refrigerator/

Thanks for the video! and it looks so easy to construct! well much easier then i was told from a swedish aquaria forum, they said that i would need two peltier/fan part to make it work?..hmm..Most of the pickninck coolers can lower about 20degrees from ambient outside temp, if we only could find a way to make that possible in large terrarium/aquarium volume.

Hi grius

yes, looks easy to build.
but the ice box is very small in the video.
and it cools air rather than water.
just wondering how much it can cool down water?

i currently have a 2ft box to house my P.chineses, i have a 300+watt chiller.
but i don't have any idea how to split it between my tanks.

Will be adding another 2ft box this week to house an axotlot given by a friend who gave up this hobby.
maybe adding a 3rd tank to house T.verrucosus in future!

1) i was thinking if i can build a icebox as above which cools water in the box
2) add 2-3 flexible steel/aluminum pipes, coil and packed it around inside the box.
3) each pipe will connect to each of my 2ft box.
4) of course a mini-pump will be needed for each box.
5) the mini-pumps will also be connected to a sponge filter and act as a filter.

is this a dream?

thanks

hi folks,

please see this

http://www.shrimpnow.com/viewarticle.php?articleid=36