[ATM] OT:Maxwell's demon

["Don Clement" <clement.focuser@verizon.net>]

I thought this might be of interest to some. The Vortex tube harnesses
Maxwell's demon to create a stream of cold air from compressed air using no
moving parts. A DIY vortex tube and information can be found here:
http://www.visi.com/~darus/hilsch/

I use a commercially available cold air vortex tube from Vortec
http://www.vortec.com/cold_air_guns.php for many operations in my shop. The
Vortec model 610 cold air gun has gotten to -7deg C from ambient of 25 deg
C. These two photos show metering with a K type thermocouple at ambient (air
off) http://i72.photobucket.com/albums/i163/miltons_stuff/ambient25degC.jpg
and with the air on a -7 deg C
http://i72.photobucket.com/albums/i163/miltons_stuff/minus7degC.jpg
BTW the digital thermocouple thermometer (SKU#92242) shown in photos above
is available from Harbor-Freight tools this week on sale for $25. It works
to temperatures of 1300 deg C. Might be useful in monitoring kiln
temperatures.

The vortex tube is horribly inefficient. My Vortec model 610 consumes 15
SCFM (425 SLPM) @ 100psi. A 5-micron filter and water trap is essential. (I
built my own  water condenser using 40 ft of ½" copper tubing and have
gotten pretty good at sweat soldering copper tubing )
http://i72.photobucket.com/albums/i163/miltons_stuff/5micronfilter.jpg

A large compressor is needed to feed Maxwell's demon voracious appetite for
compressed air. I use a 5 hp two-stage compressor with 80-gallon tank.

For dry cooling applications, the vortex tube works very well. I can imagine
a use for the vortex tube in dry grinding certain optics materials where
water cannot be used. (e.g. fluorite)

Here are a few applications in my shop for the vortex cold air gun:
Cooling a twist drill:
http://i72.photobucket.com/albums/i163/miltons_stuff/DrillingHole.jpg

Milling aluminum with ½" diameter solid carbide end mill at 4Krpm:
http://i72.photobucket.com/albums/i163/miltons_stuff/Milling4KRPM.jpg

Precision boring a 2inch diameter hole:
http://i72.photobucket.com/albums/i163/miltons_stuff/boring2inchHole.jpg

Sawing 4-1/2" diameter aluminum with bandsaw:
http://i72.photobucket.com/albums/i163/miltons_stuff/coldairgun.jpg

Don Clement
Running Springs, California




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