Anyone know how thermoelectric coolers work?

[SaltyNuts]

I think I kind of get the jist of it, but would love some confirmation. This would be to cool aquariums.

One side gets cold, the other side gets hot. The more you can cool the hot side, the colder the cold side can get.

So, in the aquarium setting, I would attach the cold side of the thermoelectric cooler to the glass (how - some kind of glue? Any ideas best kind?). I would mount on the hot side as big a heat sink as I could fit. Then likely mount a fan on that heat sink to help IT keep cool.

Does that sound about right? ANyone know of any good, cheap pre-made units that would work on an aquarium? How efficient are they generally from a watt perspective? In other words, instead of going that route, if I were instead just to get some fans that blow into/accross the top of the water, increasing evaporation, might those have a per-watt cooling effect more than the thermoelectric cooler approach?

Thanks!

 

[deadlyapp]

It's the electrons man.

By any means, peltier junctions (their more sciency name) have a fixed temperature delta which is derived by current. The more current you add, the larger the temperature difference, but as you note, you have to make sure you are properly heating one side and cooling the other.

I would not recommend putting a peltier directly on glass. Your best option would be to make a small re circulation unit that had a waterblock that was attached to the peltier and external to the aquarium.

Thermoelectric coolers have excellent energy density, so you won't be able to get any better cooling, but like i said you have to have a very strong power supply to drive one.

 

[nakedfrog]

That takes me back... how many of you nerds used peltiers to cool your Celeron 300 back in the day?

 

[herm0016]

they are not efficient at all. the thermal cycling of the glass could break it and glass is not a great conductor of heat. "glue" is also not a good conductor.

i think your best bet is something like deadlyapp suggested. should be able to set something up fairly inexpensively with computer water cooling hardware.


what do you have in an aquarium that you have to cool it? i have only ever seen people having to heat the water. also, how big? water has a huge thermal mass and you will need to move a lot of energy to cool it by a small amount.

 

[highland145]

what do you have in an aquarium that you have to cool it? i have only ever seen people having to heat the water. also, how big? water has a huge thermal mass and you will need to move a lot of energy to cool it by a small amount.

His beer....duh.

 

[zinfamous]

they put the electricity on the ice and it gets the cold.

 

[highland145]

they put the electricity on the ice and it gets the cold.

Can't you just spray it with tear gas?

 

[ctbaars]

Just drop the whole peltier cooler into the tank. Sheer volume and heat capacity of the water will cool the hot heat sink side while cooling the water on other side. Just make sure the DC power supply can deliver enough current. Check the specification sheet of the cooler and the power supply. You may have to drop the power supply into the tank too. But if you do, and this is very important, make sure it goes on the cold side.

 

[BurnItDwn]

I never used a peltier cooler, but, I read all about them back when I had the 300a and then read more after upgrading to a 533a "coppermine celeron."

 

[Red Squirrel]

They are a neat tech, but actually super inefficient, it's why they arn't really used anymore. You can also generate electricity with them. If you heat one side and cool the other, you should get an output. Never tried it myself though but I imagine it would be useful if you want to power something with a wood stove. Like say, a pump to circulate water for heating. Even if it's not efficient, if the power is essentially free, it is still useful.

 

[BurnItDwn]

They are a neat tech, but actually super inefficient, it's why they arn't really used anymore. You can also generate electricity with them. If you heat one side and cool the other, you should get an output. Never tried it myself though but I imagine it would be useful if you want to power something with a wood stove. Like say, a pump to circulate water for heating. Even if it's not efficient, if the power is essentially free, it is still useful.

IIRC, there are a bunch of projects to develop and mass produce little wood gasifiers with peltiers for charging usb devices have been trying to get a foothold in many parts of the world where the power grid is unstable...

 

[Scarpozzi]

I'd probably ping some local aquarium shops and ask what they suggest.

I mean, honestly, it's probably easier to put the aquarium in a room with a thermostat and chill the room to the desired water temp....since water is usually at "ROOM TEMPERATURE". It'd probably be cheaper to throw in a window AC unit than buy some of those specialized tank chillers.

 

[SaltyNuts]

Thanks everyone! So I'm hearing a few different things. deadlyapp said "Thermoelectric coolers have excellent energy density, so you won't be able to get any better cooling, but like i said you have to have a very strong power supply to drive one. "

But Red Squirrel said, "They are a neat tech, but actually super inefficient, it's why they arn't really used anymore."

Is the deal with them that they can be MADE to be great cooling devices, but doing so would be INEFFICIENT in that it would consume a lot of watts? Like, relative to other things, like a simple fan blowing accross of the water increasing evaporation?

I am asking because I am going to have to put some of my aquariums outside, and I live in Houston and it gets HOT here. Looking for the most efficient way to keep the aquariums several degrees (or at least a few degrees) colder than outside temp during day.

Thanks!!!

P.S. nakedfrog, you nailed it, of course I remember putting these on my 300a to 450. And 226 to 448. And K6-2 or whatever before that. Those were the days, so much fun! Do they not put these on chips any more? How the heck do they cool them? Thanks!

 

[BurnItDwn]

Thanks everyone! So I'm hearing a few different things. deadlyapp said "Thermoelectric coolers have excellent energy density, so you won't be able to get any better cooling, but like i said you have to have a very strong power supply to drive one. "

But Red Squirrel said, "They are a neat tech, but actually super inefficient, it's why they arn't really used anymore."

Is the deal with them that they can be MADE to be great cooling devices, but doing so would be INEFFICIENT in that it would consume a lot of watts? Like, relative to other things, like a simple fan blowing accross of the water increasing evaporation?

I am asking because I am going to have to put some of my aquariums outside, and I live in Houston and it gets HOT here. Looking for the most efficient way to keep the aquariums several degrees (or at least a few degrees) colder than outside temp during day.

Thanks!!!

P.S. nakedfrog, you nailed it, of course I remember putting these on my 300a to 450. And 226 to 448. And K6-2 or whatever before that. Those were the days, so much fun! Do they not put these on chips any more? How the heck do they cool them? Thanks!

Can you like ... dig a hole 5 or 6 feet deep? then, use the cooler temperature of underground to keep from boiling the fishes to death?

 

[ctbaars]

Water holds a huge amount of heat. About 4000 J/kg*K. Air is about 1 J/kg*K.

 

[ctbaars]

What about a smaller version of this?
https://www.poolsupplyunlimited.com...CdBKxiT82OqiJZEehaqJni4Z3tCnvLyIaAosiEALw_wcB

 

[SaltyNuts]

Can you like ... dig a hole 5 or 6 feet deep? then, use the cooler temperature of underground to keep from boiling the fishes to death?

I actually asked this question in another thread lol! For some of my aquariums, I'm going to bury them, not THAT deep, but like a foot or two down so that only have of the sides of the aquarium are above ground. I need some above ground so they get sunlight - they will have plants/algae growing in them. This might not help as much as if they were 5 or 6 feet deep, but should still help a good bit correct?

Thanks!

 

[SaltyNuts]

Water holds a huge amount of heat. About 4000 J/kg*K. Air is about 1 J/kg*K.

OK, but now I need to get that 4000 whatever cooled!!!

 

[BurnItDwn]

I actually asked this question in another thread lol! For some of my aquariums, I'm going to bury them, not THAT deep, but like a foot or two down so that only have of the sides of the aquarium are above ground. I need some above ground so they get sunlight - they will have plants/algae growing in them. This might not help as much as if they were 5 or 6 feet deep, but should still help a good bit correct?

Thanks!

I know here in IL, you need to dig like 3 feet to get below the frost line .... anything less than that ... and you have a lot of seasonal variation ...
In Tx, if you bury 1-2 feet deep, my instinct tells me it would help to some degree, but, by mid summer, it might be too hot.

 

[Fir]

I can't believe they actually make one but here you go!

https://www.amazon.com/IceProbe-Thermoelectric-Aquarium-Chiller/dp/B001JSVLBO

They do make chillers that work just like your fridge. It's a box with a fan and has fittings. You just plumb it so water is circulated through it.

TECs are used for a LOT of things actually. Wherever precise temp control is needed they work well.

 

[Red Squirrel]

Peltiers are inefficient in the sense that you will consume way more power per BTU than say, an air conditioner. That said, they do have their place, as they are solid state and probably very reliable compared to a standard refrigeration loop.

So depending how cold you need to go, it might make sense to get a small fridge or air conditioner, and circulate the water through it. You could make a heat exchanger. Depending how smart you want the system to be you could have various temperature sensors that control the pump and the chiller (whether it's a fridge, freezer or maybe even AC unit).

I'm guessing it does not need to be super cold, so I'm thinking a bar fridge would work. Setup a water tank inside the fridge, then coil up some copper tubing inside the tank to act as heat exchanger and have the fish tank water circulate through it. The idea is the tank inside the fridge acts as thermal storage. Then have a temp sensor in the fish tank that activates the pump when the water gets too warm. I imagine not shocking the fish is also important, so by using this indirect cooling method it should work decently while having good capacity. Suppose you could have the fish tank water go directly inside and out of the tank that is inside the fridge, but I feel it's probably best to keep it separate.

Disclaimer: I never did this before, so I can't guarantee it will work, but I'm thinking it probably would, worth a shot unless someone can confirm it won't work.

 

[deadlyapp]

Thanks everyone! So I'm hearing a few different things. deadlyapp said "Thermoelectric coolers have excellent energy density, so you won't be able to get any better cooling, but like i said you have to have a very strong power supply to drive one. "

But Red Squirrel said, "They are a neat tech, but actually super inefficient, it's why they arn't really used anymore."

Is the deal with them that they can be MADE to be great cooling devices, but doing so would be INEFFICIENT in that it would consume a lot of watts? Like, relative to other things, like a simple fan blowing accross of the water increasing evaporation?

I am asking because I am going to have to put some of my aquariums outside, and I live in Houston and it gets HOT here. Looking for the most efficient way to keep the aquariums several degrees (or at least a few degrees) colder than outside temp during day.

Thanks!!!

P.S. nakedfrog, you nailed it, of course I remember putting these on my 300a to 450. And 226 to 448. And K6-2 or whatever before that. Those were the days, so much fun! Do they not put these on chips any more? How the heck do they cool them? Thanks!

Energy density in terms of cooling for size. There's a reason why TECs are used in many compact fridges and wine coolers where the cooling needs are low, but the space constraints are high. They are very inefficient in terms of BTU/hr cooling capacity vs energy consumption (peltiers are around 10-15% efficient vs 40-60% for an AC cycle).

Either way, a peltier is probably more efficient cooling wise than simply blowing a fan over the water, because you're relying heavily on conduction (through water) and convection (top of water) and circulatory currents in the tank itself if you use only a fan, while with a peltier you'd likely be forcibly circulating the water and using conduction through some sort of water block.

Peltiers are inefficient in the sense that you will consume way more power per BTU than say, an air conditioner. That said, they do have their place, as they are solid state and probably very reliable compared to a standard refrigeration loop.

So depending how cold you need to go, it might make sense to get a small fridge or air conditioner, and circulate the water through it. You could make a heat exchanger. Depending how smart you want the system to be you could have various temperature sensors that control the pump and the chiller (whether it's a fridge, freezer or maybe even AC unit).

I'm guessing it does not need to be super cold, so I'm thinking a bar fridge would work. Setup a water tank inside the fridge, then coil up some copper tubing inside the tank to act as heat exchanger and have the fish tank water circulate through it. The idea is the tank inside the fridge acts as thermal storage. Then have a temp sensor in the fish tank that activates the pump when the water gets too warm. I imagine not shocking the fish is also important, so by using this indirect cooling method it should work decently while having good capacity. Suppose you could have the fish tank water go directly inside and out of the tank that is inside the fridge, but I feel it's probably best to keep it separate.

Disclaimer: I never did this before, so I can't guarantee it will work, but I'm thinking it probably would, worth a shot unless someone can confirm it won't work.

The feasibility is there, but you'd need to run some heat transfer equations to determine the length of tubing, the flowrates, etc. More than likely you would not get enough cooling to make any sort of useful change unless you had a huge amount of tubing within the fridge, which means then having a higher pressure pump.

 

[SaltyNuts]

Energy density in terms of cooling for size. There's a reason why TECs are used in many compact fridges and wine coolers where the cooling needs are low, but the space constraints are high. They are very inefficient in terms of BTU/hr cooling capacity vs energy consumption (peltiers are around 10-15% efficient vs 40-60% for an AC cycle).

Either way, a peltier is probably more efficient cooling wise than simply blowing a fan over the water, because you're relying heavily on conduction (through water) and convection (top of water) and circulatory currents in the tank itself if you use only a fan, while with a peltier you'd likely be forcibly circulating the water and using conduction through some sort of water block.



The feasibility is there, but you'd need to run some heat transfer equations to determine the length of tubing, the flowrates, etc. More than likely you would not get enough cooling to make any sort of useful change unless you had a huge amount of tubing within the fridge, which means then having a higher pressure pump.

Thanks deadlyapp!

So the "AC style" is that what is used in a refrigerator? Is it generally known as the most efficient cooling method possible?

Red Squirrel is definitely on to something... check out this link!

 

[SaltyNuts]

What about a smaller version of this?
https://www.poolsupplyunlimited.com...CdBKxiT82OqiJZEehaqJni4Z3tCnvLyIaAosiEALw_wcB

Whoa, just saw this, thanks ctbaars. That thing looks interesting as heck. Here is link to smallest one:

https://www.poolsupplyunlimited.com/glacier-gpc-25-residential-pool-cooler/20947p1

It is $1,600 bucks, but it claims to be able to cool 30 THOUSAND gallons by like 15 degrees. That would be the equivalent of cooling 545 55 gallon tanks lol!

It doesn't list the watts, but it says it costs "pennies a day" to operate, and "you will not even notice it on your electric bill". That sounds efficient AS HECK.

So does anyone know what process these use? Same thing as a refrigerator? Almost sounds too good to be true! Would love to get or build a smaller one, although if I could use that one linked that might work just fine, it would certainly give me an incentive to buy more aquariums lol!

Thanks!!!

 

[SaltyNuts]

Hmmm, here is a link to the energy useage of a refregirator I got and add for from Fry's. $1599, so about the cost of the device ctbaars linked. Energy usage per year?

https://images.frys.com/art/rebates_pdf/7168462_energyguide.pdf

$51. And that refrigerator is huge, it could hold so much wrapped-around tubing to have water running through it to chill it.

But I wonder how that cost, and how the cooling, might compare to the device ctbaars linked?

Thanks!!!