Gas Cooling

Ok, so I came up with an idea in the shower this morning and in my extensive home brewing readings I have yet to come across this topic.

Cooling Wort with gas!

So if you diffused CO2 into your hot wort it should cool it, and it should bind minimally due to the high temperature, right?

You could take it a step further and use Liquid Nitrogen as it should just boil off into the atmosphere causing the heat exchange.

Both would be sterile and cold, and would there be much chemical manipulation of the wort?

I know this probably isn't cost effective, but hey a lot of stuff we do isn't and experimentation is fun!

You'd waste a lot of gas, and you'd have to have decently high enough flow for the gas to be cool enough to do anything. Plus, gas has terrible heat capacity and heat transfer, so it'd take a while.

If you want to use CO2, I'd recommend dry ice over gaseous CO2, but then you have the problems of the dry ice forming a wort-ice shell and killing your heat transfer rate again...

May be helpful to cool the water that you are cooling with, but more work that its worth.

Liquid nitrogen does not work well for cooling liquids. I assume you were thinking of just pouring it in and letting the liquid/liquid contact cool it quickly, but it doesn't work. The temperature difference is so large that there is no heat transfer directly between the liquids. Rather, it goes liquid nitrogen, to gaseous nitrogen, to wort (look up the leidenfrost effect). Also, liquid N2 is less dense than water, so it only floats on the top. I have access to liquid N2 at my lab, and have mixed some in to my 1 liter nalgene many times. Even if I continuously stir the mixture, the water barely gets any colder. If you were to use liquid N2, you should probably make some kind of coil that allows the liquid to boil inside the tubing and have the gas exit through at the bottom through a diffuser.

As for CO2, shortyjacobs is correct that gas has very minimal heat transfer, but that's usually only an issue in a heat exhanger where conduction provides the most thermal resistance. If you were to pump gas through a diffuser to greatly reduce the surface area of the bubbles, you could get decent results. If you're doing that though, you may as well just use filtered atmospheric air since it's cheaper.

All that said, tossing your kettle into an ice bath or using an immersion or counter flow chiller is just much easier and faster.

I understand that this is not a simple/cheap way of cooling, I was just wondering if it was a possibility. Thanks everyone for shedding some light on why no one does it.

You really want to get your ice bath colder sprinkle it with salt. Youll go through more ice, but it will get the icebath colder.

You could run liquid co2 through an immersion chiller.

The hot/cold plates I use at work work in a similar fashion: slab of steel with passages that liquid n2 is passed through. Plates will cool down to -100c.