How to cool water fast!
How to cool water fast!
(OP)
OK, so I've been working on a few different things lately and one that I've been fumbling around with is being able to heat up water to about 70 deg C, then back down to about 38 deg C...all in less than 2 minutes too lol.
I can't really think of a way to get the water down to almost half the temperature of what it was in that short of a timespan. I'm sure by having a fan at one end of the tube of passage and having that moving quickly I could do it, but I haven't had much luck with that theory...
Any ideas would be GREATLY valued!
Thanks so much!!
I can't really think of a way to get the water down to almost half the temperature of what it was in that short of a timespan. I'm sure by having a fan at one end of the tube of passage and having that moving quickly I could do it, but I haven't had much luck with that theory...
Any ideas would be GREATLY valued!
Thanks so much!!





RE: How to cool water fast!
RE: How to cool water fast!
RE: How to cool water fast!
ione - I'm not trying to do it to a big volume of water, ~8 ounces.
RE: How to cool water fast!
Calculations NOT to follow(:<)).
RE: How to cool water fast!
Your nominal conditions will require about 253 W of cooling. Can you physically move the container from the heater to a cooler in a aluminum container? What kinds of container can you use, i.e., something with lots of fins in it?
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RE: How to cool water fast!
RE: How to cool water fast!
IRstuff - are TE coolers what's used in PCR to get the temperature to drop so quickly? I read about PCR, but didn't see anything relating to TE cooler.
And the container cannot be moved from under the nozzle to a cooler in an alumininum container. I can use any container that would allow me to pass the 70 deg C water through for a short period of time (even just a pulse), then I'd have to introduce some way of cooling that initial "pulse" down to about 38dC.
ione - the ice would definitely do the trick, but I wanted to avoid ice to reduce the temp, sorry for not including that in my description.
RE: How to cool water fast!
The thermal conductivity of ice is quite low, relative to water, but, lots of really cold water, say 5ºC, with lots of flow and lots of contact area is certainly a possibility. Hypothetically, a 32ºC reduction in 8 oz of water can be accomplished by raising 7 cups of 5ºC water to 10ºC.
How often do you need to do this, as this would scope the overall cooling capacity needed. If it's one cup per day, that's quite different than one cup every 2 minutes.
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RE: How to cool water fast!
Would a TEC do this for me?
RE: How to cool water fast!
http://www.avantiproducts.com/products/id/273
It looks like they keep the water hot. If you want the final product cooler, you add a bit of cold water from the cold water dispenser.
(By the way, there is pdf of the parts manual on the link. You might get some ideas from looking at what they use.)
Patricia Lougheed
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RE: How to cool water fast!
RE: How to cool water fast!
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RE: How to cool water fast!
RE: How to cool water fast!
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RE: How to cool water fast!
Have you thought about adding dry ice? I used to use that to kick start the process.
RE: How to cool water fast!
macmet - I thought about dry ice, but I'd like to refrain from using ice to do this as I want as little operator assistance during use. Thanks for the input though!!
RE: How to cool water fast!
Since 4.186 J is needed to drop water by 1dC, I did 4.186*32=133.952. And since 1 watt=1 Joule/1 sec, I don't see where you got the 253.
I probably calculated it wrong, but if so, where did I go wrong in my calculations?
RE: How to cool water fast!
Specific heat of water = 4187 J/kgK
Temperature decrease = 32 °C
Time = 2 mins = 60 seconds
Power = 4187 * 0,223 * 32 /60 = 498 W (approx). Obviously if time available for cooling process decreases power will increase
RE: How to cool water fast!
RE: How to cool water fast!
Shouldn't it be ~249 W since it's going to be over 2 minutes
> That sounds familiar!
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RE: How to cool water fast!
RE: How to cool water fast!
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RE: How to cool water fast!
RE: How to cool water fast!
RE: How to cool water fast!
You could even use a tube-in-tube heat exchanger where cold water flows through a copper tube into a heated metal block, gets hot, and then flows out of the block through a tube that surrounds the the copper tube with the water coming-in (a counter-flow heat exchanger).
RE: How to cool water fast!
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RE: How to cool water fast!
I used TEC's to cool the propylene glycol.
RE: How to cool water fast!
Compositepro and macmet - I like those ideas too, so I'm going to give yours and IR's a shot to see which is best for my application! Thanks!
RE: How to cool water fast!
The precool temperature should be as low as practical, since thermal transfer is proportional deltaT. The colder the serpentine, the faster it cools, provided you don't get freezing or other annoying side effects of cold objects.
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RE: How to cool water fast!
RE: How to cool water fast!
Stacking/staging doesn't work for larger heat loads - each layer has to remove the heat from the previous TEC as well as the electrical power supplied to that previous TEC.
This is important - a 200W TEC puts out way more than 200W of heat on the hot side and only removes 200W of heat on the cold side for large delta T.
People also tend to underestimate the electrical power supply for TEC's - they can really eat up the amps.
On the other hand, reverse the polarity and the TEC's become heaters so you could use the same TEC's to heat and then cool the fluid.
I don't quite follow why you would want to open/dismantle the TEC's? Are we talking about the same thing here - thermo-electric coolers, also known as Peltier coolers...
See this site for more info (albeit for computer cooling):
http://w
Adriaan.
I am a Mechatronics Engineer from South Africa.
www.martin-electronics.co.za
RE: How to cool water fast!
bithkits - I heard the same thing from one of the other engineers here yesterday, which kind of gave me second thoughts about that. Also, it seems to be a little more expensive than what we were looking to spend.
RE: How to cool water fast!
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RE: How to cool water fast!
RE: How to cool water fast!
My plan for this is:
1. Have the 70°C water running through the Silicone tubing that I have
2. Insulate the Silicone tubing with the PCM which would be encapsulated with a copper tube.
Does this look like something that would work or am I misunderstanding PCM's?
RE: How to cool water fast!
RE: How to cool water fast!
You'd need to come up with some sort of flow-through sieve-like structure that won't contaminate your samples with itty-bitty balls of PCM. Then you need to bring the PCM back down below its melting point, which requires some sort a cooling system.
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RE: How to cool water fast!
RE: How to cool water fast!
You really need do the analysis, and your unfamiliarity with how the cooling is being accomplished is severely hampering your path to a solution. You should read up on heat transfer; there are gobs of resources, including Wikipedia, a free HT textbook: http://web.mit.edu/lienhard/www/ahtt.html all on the web.
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