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Vortex tube again

Hi All,

I know this topic has been talked about before, but I finally got a round toit and decided to build a Hilsch Vortex tube. I did some research on the Net and did not find a whole lot. I did some research on the USPO web site several commercial sites, Chapman?s doctoral thesis and some work copied from Scientific American

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Of all I found, the SA stuff was the most useful. There seems to be plenty of info on the theory of the device but very little on the construction of the device. It seems that one would want to fare all joining surfaces, but the illustrations show right angles and irregularities the that ought to cause eddies and other discontinuities.

So I finally just bit the bullet and tried something. The resulting device was less than spectacular. I based it on 3/8 pipe and used the following relationship. D= .375? d= .165? B= .087? The length of the cold tube = 4? The length of the hot tube = 12?

Well the hot tube got hot and the cold tube got cold, but not very. I got a temperature change of about 30 degrees F at best. I know the tubes are pretty inefficient but the commercial tubes can get very cold, so I am obviously lacking something in my construction technique.

Is there any one of this esteemed group that has made any of these or has any knowledge of their construction or can point me in the right direction? I would love to see some actual plans where someone has been able to optimize one of these little buggers.

This seems to be one of those devices that everyone knows a little about it, but few seem to know very much about it. I am really surprised

TIA

Jay Cups

Reply to
JayCups
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Like you, I hit all the resources I could find on the 'net. Like you, I bit the bullet and tried to build my own version and surprise,surprise I got room temp air to drop 30-40 degrees F. I tried many iterations of the tube to no avail. I finally bought an Ebay Vortec vortex tube and was able to get...about the same results!!! I called Vortec and talked to their technical staff and was told that the best results are obtained with a pressure of 100psig and, get this, a flow of 15-25 CFM! Now I'm no compressor expert, but that seems like one mother of a compressor, definitely bigger than my 25gal model. Keep us informed if you get better results!

Rich

Reply to
eyeclinic

Basic physics is basic physics! That is what you get. If you want anything better, go dig into the physics of how they operate and optimize from there.

-- Why do penguins walk so far to get to their nesting grounds?

Reply to
Bob May

Dr. Stong's legacy comes through again. I built that tube back in the early '60s when the original Amateur Scientist article came out. Best I could do was get about 110F difference between the hot and cold side. Experiment with the size of the hole in the diaphragm.

Reply to
Glenn Ashmore

According to JayCups :

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Well ... I played with making one many years ago, and it did not work at all, until I discovered that I needed to make the apertures the same diameter -- though one (to the cold tube) was right at the injection point, and the other was at the far end of the hot tube. There does need to be a significant difference in diameter at the injection point, but before the hot side exits, it needs to be reduced to the same diameter as the injection point for the cold tube. (I was using something like 1/2" copper tubing with a quick-and-dirty center made by milling angled insertion vents into a coupling.) The injection point to the cold tube was about 1/4" or so. I finally got results by restricting the hot tube open end with my thumb (at which time things got uncomfortable), so I used a pair of pliers to squeeze the tube down around a 1/4" bolt and then removed the bolt to get reasonable balance.

These things are never very energy efficient, so they may be fun to play with, but are not reasonable as air conditioning. :-)

(Though the first examples that I saw were being used by the Army as an experimental way to pipe cold air to the helmets and necks of tank operators. There, the lack of efficiency, and the noise were no problem, considering the rest of the operating environment. :-)

Probably you can improve the efficiency by adjusting the ratio of the large and small diameters at the injection point -- and making sure that the design does induce a serious vortex.

Enjoy, DoN.

Reply to
DoN. Nichols

Seems like many of us have tried it over the years. I've got one that I still use once in a while. I made it around 30 years ago when I didn't have any machine tools, just a drill press, so it was rather crude. But surprisingly, the cold side gets down to 8 degrees F. A nice layer or ice forms around the whole length of the cold tube. Never measured the hot side. It does take a lot of air, 150 psi from a 5 hp. I'm not sure of the CFM, but it's less than the 5 hp is putting out. The bore of the tube is only 0.175", 3.75" cold length, 6.875" hot length. The hot side is plugged and drilled with a 0.80" exit hole. A small adjusting screw can make the hole smaller, and the best setting reduces the size a little.

Reply to
Billy Hiebert

Thanks for the responses. The more research I do on this the more interesting it gets. Kinda like Nitinol, all kinds of potential applications, but not much commercially viable. Right now, I'd be satisfied with Glen's 110 degree delta. And it is a great way to escape to my shop and forget the problems of the world.

Jay

Glenn Ashmore wrote:

Reply to
JayCups

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