Celticway
Well-Known Member
Any one ever tried using dry ice around an immersion chiller to pre cool your water before it goes into a CFC?
Wouldn't dry ice be exponentially expensive compared to the same effective amount of "wet" ice?
i have had success using tap water to get down to about 120 and then re-circulating the cooling water over ice.
If you want the ice bath pre-chiller to be cooler you can add salt to the bath. But, i do not see the need for this. A regular ice bath should easily maintain at near freezing temps until you start dumping hot water in it.
Rather, I would invest in a larger mass of ice bath before buying dry ice. If one doubled the size of the ice bath from a 5 gallon bucket to a 10 gallon tub, one would have twice the thermal mass and would be able to sink more heat into the ice bath per degree of temperature change of the bath. Thus allowing you to cool your wort further.
Of, in other words... use a larger ice bath because water and ice a cheap.
Sardoman said:Dry ice would freeze the water in your prechiller, possibly ruining the prechiller when the ice expands.
Shockerengr said:Some things to keep in mind: Just because something is really cold, it doesn't mean that it has a lot of capacity to cool.
[specific] Heat capacity, heat of fusion (energy required to melt/freeze), heat of sublimation (energy required to go from solid to gas for dry ice) and heat of vaporization (liquid to gas for liquid nitrogen) are the factors that affect how much cooling you get.
Water has a high heat capacity, and takes a fair bit of energy to change it's temperature.
What you end up with is a pound of ice provides much greater cooling capacity than a pound of dry ice or pound of liquid nitrogen.
Dry ice is great and used often because it can cool far below freezing, and when used up doesn't leave anything behind...so it's great for food. Liquid nitrogen is used when extremely low temps are required.
Since with beer, neither of those two items are needed, dry ice and liquid nitrogen don't really provide a benefit.
Now that said, if you can get dry ice for nearly free or much less than ice (figure 1/4 to 1/2 the cost per pound) then you may have an advantage in your specific situation.
As for freezing in the prechiller...if it sits stagnant you'd have a risk, but under flow you should be fine. I'd actually still have it in a water bath to get better heat transfer...as the dry ice sublimiates, you'll only have gas next to the coils otherwise with a very low heat transfer rate.
Makes sense to me. Thanks.
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