air cooled stripping still

rangaz · Post by **rangaz** » Mon Mar 12, 2007 4:39 am

I've been toying with the idea of a high powered (enough to cool a heavy duty propane burner), air cooled pot still head to fit onto my 50L keg for a while now. It would make for a fast, low hassle stripping run to prelude the spirit run in the reflux. I have several incredibly long pieces of 1 in copper and have been trying to come up with a good design. I know very little about thermodynamics and am going to ask for the help of someone who does.

I saw a diagram on the parent site a while back, which I cant seem to find now, but it was basically a length of 1in angled down from the still head, with a series of circular, aluminium fins with their plane perpendicular to the direction of the condenser, so it looked like it had a series of rings. This then had a fan blowing over it. The problem I see with this is that the airflow produced by the fan passes over very little of the fins huge surface area, thereby decreasing its cooling capacity.

My thought was to run a series of waffles in a direction parallel to the direction of the condenser with a tube around to direct the airflow along the condenser, thereby maximising the waffle to air contact.

It would be very helpful for someone who has actually tried this or knows something about thermodynamics to give some input.

pintoshine · Post by **pintoshine** » Mon Mar 12, 2007 7:38 pm

I don't know the thermodynamics of your setup but I can relate some personal results with air cooling. I wound 50' of 5/8" soft tubing in a spiral that has a 12" diameter. I soldered the tubs with a 3/8" spacing between each turn. I blocked off on end of the spiral with a sheet of aluminum and blow air down through it with a small box fan. If I run it hard, alcohol coming off at 140°F I can sink 2200W of input. Air doesn't provide much heat transfer with copper tubing.

: condenser1.jpg (10.23 KiB) Viewed 2649 times

This is my smallest pot still setup.

AllanD · Post by **AllanD** » Wed Mar 28, 2007 1:22 pm

You might want to consider using aluminum finned copper tube baseboard radiator elements.

These are typically 3/4" copper pipe (actually 7/8" diameter)
And the larger diameter will slow the vapor speed through the tube so that good thermal transfer is more likely...

AllanD

bushido · Post by **bushido** » Wed Mar 28, 2007 6:24 pm

That's quite the coil there Pinto. Nice job. I bet if you used a turbo fan such as sold by LTI, 12", 1300 M3/hr, you would have no problem with cooling that puppy. Hah, it may take off!

pintoshine · Post by **pintoshine** » Fri Mar 30, 2007 8:55 pm

Thanks for the compliments.
I have two or three of these from past stills. I always liked the air cooled machines. Cheap.
This might seem strange but the thing I like most about the air cooled coil is feeling when it gets hot when the vapor starts coming in. You can hold your fingers on the top coil until it gets too hot and then move down one, and etc.
You just want the third or fourth coil to be cool enough to touch. Then you get no blow by. So what if the alcohol comes off hot as long as it comes off liquid. I ain't inhaled enough alcohol vapor yet to get drunk. The liquid is a different story.

hornedrhodent · Post by **hornedrhodent** » Sat Mar 31, 2007 5:10 am

pintoshine wrote: I ain't inhaled enough alcohol vapor yet to get drunk. The liquid is a different story.

You gotta stop laughing while drinking!