I'll get some pics of my setup. Guess I need to find a vacuum gauge. Or maybe a long skinny piece of clear pipe. I've been looking for something to do with that bottle of mercury in the shop!
Wort Chilling - New Idea
- Thread starter hazaramj
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I'll get some pics of my setup. Guess I need to find a vacuum gauge. Or maybe a long skinny piece of clear pipe. I've been looking for something to do with that bottle of mercury in the shop!
conpewter
Well-Known Member
Those Hobart mixing bowls are really hefty, so I wouldn't doubt that you can pull a considerable vacuum on them. I'm looking forward to your results and some pics!
I have not heard this before. Not to get off topic from the OP but do you just put the dry ice directly in the wort? If so, how much for a 5 gallon batch?
billvon
Well-Known Member
Indeed. Take a Boilermaker 15gal pot. At .023atm absolute pressure inside, there would be 2800 pounds pushing on the bottom of the pot alone.
MarzBock
Well-Known Member
Pulling a vacuum on hot wort would do a couple of things..
It would cause the wort to boil easier, at reduced pressure. The process of "boiling" under reduced pressure is endothermic, ie: heat is absorbed. If there is no longer a heat source, the temp WILL drop as the pressure is reduced further until the vapor pressure of the wort is equal to the reduced pressure from the vacuum. Cooling will ONLY occur during this period where the vapor pressure of the hot wort is higher than the reduction of pressure from the applied vacuum. It is the process of "boiling" under reduced pressure that causes the loss of heat.
This WILL chill the wort, but it will also generate a lot of water vapor (steam) that will either go through the vacuum pump (if it's a diaphragm pump) or it will get absorbed by the pump oil (if using a high-vac pump). If a high-vac pump is used, a cold-trap should be employed to condense out the water vapor as it will reduce pump efficiecy if absorbed into the oil.
It's an interesting idea, but honestly, it sounds like a lot of work for very little pay-off. Vacuum pumps are expensive, and one would need to have a boiling kettle that is vacuum tight. I don't think a pressure cooker would work, as they are designed to handle positive pressure, not reduced pressure. You would also need a lot of head space to handle the foaming/boiling of the wort as pressure is reduced. In the lab, we call this "bumping" and things can get out of control quickly if there is no internal agitation (like stirring with a stir plate).
Dry ice would be an option, as someone mentioned. I would be a little concerned about localized freezing of the wort. If the kettle is in contact with dry ice, it could potentially freeze it against the sides of the kettle if there is no internal stirring. Dry ice is really cold (-78C or -110F), so it could be possible to accidentally freeze the wort in contact with the sides of the kettle. stirring during the cooling process would be the only way to avoid this.
I work as a bench organic chemist, so I do have experience with this kind of stuff...
marz
It would cause the wort to boil easier, at reduced pressure. The process of "boiling" under reduced pressure is endothermic, ie: heat is absorbed. If there is no longer a heat source, the temp WILL drop as the pressure is reduced further until the vapor pressure of the wort is equal to the reduced pressure from the vacuum. Cooling will ONLY occur during this period where the vapor pressure of the hot wort is higher than the reduction of pressure from the applied vacuum. It is the process of "boiling" under reduced pressure that causes the loss of heat.
This WILL chill the wort, but it will also generate a lot of water vapor (steam) that will either go through the vacuum pump (if it's a diaphragm pump) or it will get absorbed by the pump oil (if using a high-vac pump). If a high-vac pump is used, a cold-trap should be employed to condense out the water vapor as it will reduce pump efficiecy if absorbed into the oil.
It's an interesting idea, but honestly, it sounds like a lot of work for very little pay-off. Vacuum pumps are expensive, and one would need to have a boiling kettle that is vacuum tight. I don't think a pressure cooker would work, as they are designed to handle positive pressure, not reduced pressure. You would also need a lot of head space to handle the foaming/boiling of the wort as pressure is reduced. In the lab, we call this "bumping" and things can get out of control quickly if there is no internal agitation (like stirring with a stir plate).
Dry ice would be an option, as someone mentioned. I would be a little concerned about localized freezing of the wort. If the kettle is in contact with dry ice, it could potentially freeze it against the sides of the kettle if there is no internal stirring. Dry ice is really cold (-78C or -110F), so it could be possible to accidentally freeze the wort in contact with the sides of the kettle. stirring during the cooling process would be the only way to avoid this.
I work as a bench organic chemist, so I do have experience with this kind of stuff...
marz
MarzBock
Well-Known Member
The risk of implosion on a kettle is not an issue in this situation. The wort would all have to boil away before the kettle would implode, as the liquid will always vaporize before an implosion event could occur.
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ongreystreet
Well-Known Member
If you're going to use compressors to cool the wort, why not just use refrigeration to cool the wort? Just send chilled water thru your wort chiller.
Oh, I'm not trying to cool wort with it... I was just taking about the ease of getting a 'good enough' vacuum pump from an old freezer (yes I know, this is not a lab grade, cryo grade, refrigeration grade vacuum. It was just a suggestion so that if the op wanted to test the idea, he could cheaply get a pump.) The bowl I have is also no longer food safe. It's mixed lots of stuff that don't need eatin!
It pulls about 27 inches of mercury. We use it for degassing experimental composite rocket propellant.
Cheap and dirty, but it's worked for several months now. If it ever kills over, we'll trash it and get another from the local appliance shop. Nothing to it.
smiths9312
Well-Known Member
I wonder if you could send the hot wort to space for a quick chill in vacuum and it is really cold in space too.
MarzBock
Well-Known Member
wow... that is one ghetto looking vacuum pump! experimental rocket propellant, ehh? I like your style. You would approve of my pnuematic potato gun/flaming barbie doll launcher... too bad it exploded in my face last summer. cheap ass PVC.
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