Refrigeration using Peltier device
Refrigeration using Peltier device
(OP)
Hello everyone,
I'm carrying out a project which provides the cooling of a fluid inside a tube. In particular I should cool water or a glycolytic solution from a temperature of 25 °C to about 0 °C. I thought to do this through the use of the thermoelectric effect, then the Peltier cells.
I have two ideas. The first involves the use of a fluid reservoir and the cold face of the Peltier cells is in contact with the bottom of the container (figure). I thought I could get at the bottom not just one but multiple cells .
The second one is to use a system which is a kind of enclosure of the tube in which the fluid flows (figure).
I can give you some more information:
Case 1) deltaT = 25 °C -> 25 °C to about 0 °C
fluid volume / container -> 1 liter
container size -> might be 10 cm x 10 cm x10 cm
thick container -> 1mm steel
Calculating the heat subtracted from the volume of water: Q = 4186 * 1 * 25 = 104kJ. So if I want that the refrigeration is about 10 minutes I have to subtract cooling power of 104kJ/600s = 174W. Because of the dispersion may well need more than enough, say 200W (but it is a random number, I have not done any calculation).
With cells taken, for example, I run the following calculations: I took that model because one side is 47mm and the bottom of the container there are 4.
Their power is 72W and the maximum temperature difference of 74K, which means that for each kelvin of difference between the temperatures of the two faces is lost approximately 1W.
The thermal resistance of the steel wall is negligible.
4-cell 72W make 288W, 200W serve to us, means that we have 88W for the internal conduction of the cells, which means 22W per cell; then the maximum temperature difference between the two faces must be of approximately 22K.
Since the bottom of the container is at about 0C, the other face of the cells at the maximum can go to 22C. If the air is at 20C, I have a temperature difference of 2K to dissipate from the area to 1dm^2 a power equal to 4x (13.1Ax8.8V +50 W) = 660W.
Then I need a heatsink with thermal resistance of 2K/165W = 12mK / W for each cell. Or a single heatsink of 2K/660W = 3mK / W.
CALCULATION ARE RIGHT?
Case 2) flow -> 1l/min
deltaT = 25 ° C -> 25 ° C to about 0 ° C
wall thickness -> 0.1mm
In this case I would understand if it is possible and if the cooling depends on the length of the tube and such other factors.
I know that in the market there are some chillers that use the traditional refrigeration cycle but also the thermoelectric effect.
Also, if someone knew other methods to achieve my goal can tell me please.
Thank you to all, Emanuel
I'm carrying out a project which provides the cooling of a fluid inside a tube. In particular I should cool water or a glycolytic solution from a temperature of 25 °C to about 0 °C. I thought to do this through the use of the thermoelectric effect, then the Peltier cells.
I have two ideas. The first involves the use of a fluid reservoir and the cold face of the Peltier cells is in contact with the bottom of the container (figure). I thought I could get at the bottom not just one but multiple cells .
The second one is to use a system which is a kind of enclosure of the tube in which the fluid flows (figure).
I can give you some more information:
Case 1) deltaT = 25 °C -> 25 °C to about 0 °C
fluid volume / container -> 1 liter
container size -> might be 10 cm x 10 cm x10 cm
thick container -> 1mm steel
Calculating the heat subtracted from the volume of water: Q = 4186 * 1 * 25 = 104kJ. So if I want that the refrigeration is about 10 minutes I have to subtract cooling power of 104kJ/600s = 174W. Because of the dispersion may well need more than enough, say 200W (but it is a random number, I have not done any calculation).
With cells taken, for example, I run the following calculations: I took that model because one side is 47mm and the bottom of the container there are 4.
Their power is 72W and the maximum temperature difference of 74K, which means that for each kelvin of difference between the temperatures of the two faces is lost approximately 1W.
The thermal resistance of the steel wall is negligible.
4-cell 72W make 288W, 200W serve to us, means that we have 88W for the internal conduction of the cells, which means 22W per cell; then the maximum temperature difference between the two faces must be of approximately 22K.
Since the bottom of the container is at about 0C, the other face of the cells at the maximum can go to 22C. If the air is at 20C, I have a temperature difference of 2K to dissipate from the area to 1dm^2 a power equal to 4x (13.1Ax8.8V +50 W) = 660W.
Then I need a heatsink with thermal resistance of 2K/165W = 12mK / W for each cell. Or a single heatsink of 2K/660W = 3mK / W.
CALCULATION ARE RIGHT?
Case 2) flow -> 1l/min
deltaT = 25 ° C -> 25 ° C to about 0 ° C
wall thickness -> 0.1mm
In this case I would understand if it is possible and if the cooling depends on the length of the tube and such other factors.
I know that in the market there are some chillers that use the traditional refrigeration cycle but also the thermoelectric effect.
Also, if someone knew other methods to achieve my goal can tell me please.
Thank you to all, Emanuel





RE: Refrigeration using Peltier device
RE: Refrigeration using Peltier device
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RE: Refrigeration using Peltier device
RE: Refrigeration using Peltier device
RE: Refrigeration using Peltier device
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RE: Refrigeration using Peltier device
Keep the plate as thin as is reasonable, maybe 1/4". (this is about 2 ft/sec)
Then mount the TEC's to this plate. The surface that they mount to will need to be very flat and smooth.
If you arrange this right you could have each TEC cooling a different temp range, they would each need to be on separate plates for this to work.
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Plymouth Tube
RE: Refrigeration using Peltier device
EnergyMix - I started the project at the university but now I will made it myself.
IRstuff - Ok, I know that just because my fluid passes by a Peltier cooler doesn't guarantee cooling. But in the first case I have a reservoir and I do the math but I don't know in it is feasible in terms of voltage, supply, power, etc..
RE: Refrigeration using Peltier device
To dissipate the heat generated, we took an oil radiator (I think) off of an old car from the local wreckers and hooked up some large computer fans to it.
I was working at a department store at the time and a couple "accidents" happened, leaving a couple decorative fountains destroyed, and I kept the pumps, which we used on the cold side to circulate the fluid.
What we found worked well was putting the radiator in a chest freezer. Then we discovered it worked even better if we used sub-zero temperature glycol on the "hot side".
And finally we came full circle and just kept a bucket of glycol in the freezer with the fountain pumps and when we wanted a cold beer, we put the beer in the bucket, turned on the pumps, and two minutes later the beer was cold.
It was a very impressive looking device, but it took a long time to cool the glycol. Once you got it up and running it was pretty cool, but it was not very efficient. It just took a long time to get the temperatures we needed. It was definitely a lot of fun though.
RE: Refrigeration using Peltier device
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RE: Refrigeration using Peltier device
We used to stack them (cascade).
We could get -50C or so under full CPU power. The TECs drew twice as much power as the computer, but we could really overclock processors.
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Plymouth Tube
RE: Refrigeration using Peltier device
RE: Refrigeration using Peltier device
macmet - Thank you to describe your experience! I saw (on the web) that exist some water chillers for marine aquariums that uses thermoelectric module to cool water; but in this case the deltaT is lower than mine.
RE: Refrigeration using Peltier device
Think again, and consult a heat transfer book, or at least, read this: http://en.wikipedia.org/wiki/Biot_number
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RE: Refrigeration using Peltier device
May I ask what your actual application is? Just curious.
RE: Refrigeration using Peltier device
we looked at peltier diodes for a medical device and finaly came to the conclusion that they were not efficient enough for our purpose.
we ended up using a miniature refridgeration compressor.
B.E.
http://www.aspencompressor.com/Application.htm
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
RE: Refrigeration using Peltier device
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RE: Refrigeration using Peltier device
My study is about an endovascular device used to induce hypothermia. It is composed by a cvc catheter (central venous catheter) and an external device used to cool the fluid which will flow inside the catheter.
Inserting the catheter in a vein (femoral, subclavian or jugular), we can do an heat exchange between it and the blood which flow through the vessel and which is in contact with the external surface of the catehter (countercurrent heat exchanger).
I have already do some thermodinamical, geometrical and other analizes on the catheter and now I would to know how I can realize the external device.
In the marke there are 2 device, but they are expensive and also enough cumbersome; I though the use of TECs because of they are relatively cheap and less cumbersome.
berkshire
thak you!
RE: Refrigeration using Peltier device
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RE: Refrigeration using Peltier device
For the Biot number I read some information in your link. I had consider a stirrer for uniform the temperature inside the reservoir.
RE: Refrigeration using Peltier device
We definitely experienced some large blocks of ice during our creation.
RE: Refrigeration using Peltier device
RE: Refrigeration using Peltier device
RE: Refrigeration using Peltier device
RE: Refrigeration using Peltier device
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