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Joe gwinn Joe gwinn is offline
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Default Get -40C in my fillet weld tensile break tests

On Sun, 7 Feb 2021 15:12:01 -0800 (PST), bruce bowser
wrote:

On Friday, February 5, 2021 at 6:33:30 PM UTC-5, Joe Gwinn wrote:
On Fri, 5 Feb 2021 17:40:49 -0500, "Jim Wilkins"
wrote:

"Joe Gwinn" wrote in message
...
...
Have liquid propane in the sealed copper boiler with a tube going
uphill to a copper condenser cooled by dry ice in alcohol.
...
The copper stuff can be ordinary plumbing tubing and fixtures. For a
one-off, plumbers solder is good enough. For a true seal, braze with
phosphorus-copper brazing filler, as used for HVAC systems.
...
Joe Gwinn

---------------------

The pipe fitting that enables making a condenser or similar concentric tube
structure is a pipe reducer with the smaller end bored through on a lathe.
Brass is easier than copper to chuck and turn. A 6-jaw chuck helps hold the
reducer without (much) distortion, or you can jam a fitted wood plug into
the large end.

I don't visualize this.

What I was thinking was a simple one-pipe system, with vapor going up
and condensate running down. The propane inventory need not be large.
When I learned industrial refrigeration in the 1970's this is what we brazed
joints with:
https://www.amazon.com/Lucas-Milhaupt-95150-Sil-Fos-Brazing-Alloy/dp/B06Y1N5517

Yeah, that's the stuff.

If you braze all the joints, you can hermetically seal the propane
inside the heat pipe. Make sure that the total volume is large enough
to prevent overpressure damage at room temperature. Or provide a
pressure releas valve and refill before each use.


Instead of the research grade propane, the fuel grade propane (R-290) may have around 5% methane (R-50) and butane (R-600) mixed in.


Yes. The methane will do nothing, and the butane will freeze in the
condenser. As long as the condenser is large enough, it won't matter.

Joe Gwinn