I have water filled sealed aluminum containers that I freeze to 0F used to rapidly cool a boiling liquid (don’t ask). Would there be any advantage to add salt to the containers? Or glychol?
Zymurgist
I noticed that your tagiline said, “Zymurgist,” so I’m guessing you’re using these containers to chill the wort after the boil. I use a coil of copper tubing with water running through it to accomplish this. I guess you have some reason you can’t do this, since this appears to be standard practice among zymurgists. So:
Adding glycol will actually decrease the heat capacity of the containers. It actually takes less heat energy to raise the temperature of a volume of glycol a given amount than it would a similar volume or water. Thus, less cooling for your wort. The reason professionals use glycol is that it can be chilled very cold and still remain liquid, so it can be pumped through a heat exchanger system rather than an add-remove system like you’ve described. I would also be worried that one of the containers might break or leak, ruining the batch.
I’m not sure what the effect of adding salt to your containers would be, but I’m guessing it’d be minimal at best. Far more effective to use more containers.
A committee is a lifeform with six or more legs and no brain.
Thanks, Jo3sh! You’r right, I us them to cool wort as quickly as possible. I also pump wort through a lengh of coiled copper tubing in a salted ice bath. I found the combination to work very well. My water is metered so I use these other methods. I thought the addition of salt to my containers might make the process a bit more efficiant…Nice to know a fellow…
Zymurgist
I’m not a zymurgist, but I did take chemistry a few years ago (let’s not say how many).
Adding salt to water lowers the freezing point of the resulting solution, so your containers will be a little colder than normal. Old-fashioned ice cream machines, for example, use an ice bath to chill the ingredients. If you add salt to the ice, you can get the temperature down to about minus five degrees celsius (compared to zero degrees for pure ice).
In fahrenheit, this means going from 32 degrees to about 23 degrees.
Hope that helps. 
– Sylence
Another day, another attempt to cross Niagra Falls on a tightrope. . .
Sylence:
I disagree. Yes, adding salt to the solution in the containers will reduce the freezing point of the solution, but will not make them any colder than they are now. Reason: Whatever temperature Carl’s freezer is (say 0C, 32F, just for convenience) will determine the actual temperature of the ice formed. In other words, addind salt to the liquid before it’s put in the freezer will not allow it to keep getting colder until it’s below the temperature of the freezer.
The operative question is whether adding salt will alter the heat capacity of the ice. As I said above, I don’t know, but I have a feeling that it would. However, I don’t think the small gain would be worth the risk of one of the containers breaking or leaking (remember, these containers are going from a freezing environment to a boiling one very quickly, and therefore are subject to substantial heat-induced stresses), and ruining Carl’s work (and I know it’s work, too). Far more effective would simply be to add more containers.
A committee is a lifeform with six or more legs and no brain.
Okay, I’m a moron. You can get pure water ice down to -5 degrees centigrade if your freezer is that cold. Apparently I thought that ice only got so cold.
I can’t believe it took me fifteen minutes to figure that out.
– Sylence
Another day, another attempt to cross Niagra Falls on a tightrope. . .