Quick wort cooling

[GoPackGo]

I'm looking to cool a gallon of wort from ~210F to 70F as quickly as possible. The wort is contained in an aluminum can, about the size of a paint can. At first I was thinking of placing the can in a styrofoam cooler and filling dry ice in around it, but after seeing this thread

https://www.homebrewtalk.com/f11/dry-ice-pre-chilling-266409/

I'm starting to think that won't work as well as I thought. Alternatively, I'm now thinking I could fill ice water around the can. To make the ice water as cold as possible, it would be almost completely ice, with only enough water to fill in the space around it (so the entire submerged surface of the can is in contact with it). Do you think this is a good idea / am I going in the right direction? Or are there better ways to cool as quickly as possible? I'd like to do this as cheaply as possible, and the whole thing must be relatively compact.

 

[GoPackGo]

oops double post

 

[runningweird]

add salt to ice mixed with a bit of water - it will lower the freezing temp and allow the temp to go lower. or, throw it in an ice cream maker with the ice/salt mix around it - that would be interesting to see.

 

[audger]

what is the purpose of this (regular brewing chiller, or some special experiment...?) and how much volume of liquid do you have?

the problem with dry ice around the can is that gas is a poor conductor of heat. dry ice wouldnt be in direct contact with the can, only CO2 gas and air would.

a 50/50 mix of glycol and water will let you chill it down to 10-20 degrees, then dunk the can in it. if you need it to cool extremely fast, use a very large resevoir (in relation to the amount of wort) of glycol/water and keep the can moving the entire time to keep it all uniformly mixed.

if this was for some experiment and not necessarily regular beer making, and you needed extremely, extremely fast- you could use ethlyne glycol instead of (food safe) propolyne glycol, and chill it down to well below zero. food safe glycol turns to slush around those temperatures. just have to be careful about not contaminating something you would be ingesting with toxic anti-freeze. if it was for some experiment and not for consumption (or you were really sure the aluminum container was sealed), this wouldnt be an issue.

 

[GoPackGo]

Yeah, this is for an experiment (sorry, I probably should've been more clear about this earlier). I'm trying to cool 1 gallon of liquid. Antifreeze and salt are good ideas...I think I'm leaning more toward salt, just because it would be cheaper.

We ran a test of just putting the can in an ice bath last night, and it took about 11 1/2 minutes to cool. The biggest problem is that the paint can has a really poor volume to surface area ratio. We need to figure out how to increase the amount of surface area exposed to ice/water. We thought perhaps pouring the wort through a submerged copper coil and into a second container.

 

[GoPackGo]

So last night we did some more testing. Using 8 pounds of ice, 1.5-2 gal of cold water, and a pretty big chunk of dry ice at the bottom, we were able to cool our wort to 70F in 6 minutes. I almost think that this worked well because all the bubbling from the submerged dry ice caused forced convection heat transfer to take place, rather than just conduction with the can in stagnant ice water. We're going to try it again with more (wet) ice and salt in the bath and see where that gets us.