DIY Homemade Ranque-Hilsch Vortex Cooling Tube

Nothing really says Labor Day Weekend to me like a homemade vortex cooling tube! Well maybe not... but  I always wanted one and they really aren't that hard to make. I built one in one afternoon in the garage from PVC pipe, glue, a few tube fittings, a adjustable clamp and some sawing and filing...  The cool thing about them is there are no moving parts or high tolerance dimensions to hold when making your very own vortex cooling tube! All you need after building it is compressed air to get it to run and you get hot air out one end and cold air out the other. Here is how I DIY'ed a cooling tube and a little bit about how they work. The first picture below is what I ended up with. You can get anywhere from 10deg C to 70deg C cooling with these kinds of devices. I got about 15 C with mine but I bet I could get more if I tinker with it a bit.
UPDATE 8/28/10: I have added some videos explaining how I built this HERE!!
Check them out! 

  

Finished Vortex Cooling Tube

UPDATE 7/8/11 I made a smaller Vortex Tube and got much better results and posted info about building it HERE and well as a Video covering the construction HERE. I also created a Vortex Tube FAQ page HERE have a look at those pages if you are interested in building a Vortex Tube or if you just want to know more about them. Questions / Comments? leave some comments or email me at ottobelden@yahoo.com !!
   
These devices have been around for a long time and have some practical uses in industrial applications from sewing machines to welding. The principle of operation is that compressed gas at a significant pressure is sent into a tube through tangential holes or nozzles somewhere near the middle of the tube. Essentially these holes are going into the tube "right on the edge" so that when the gas enters it creates a 'swirling vortex' of gas. Sounds high tech!!! The gas swirls down the tube and there is a separation process due to the kinetic energy in the gas and you end up with cooler gas in the center of the tube and hotter gas on the outside. The cooler region can be and usually is cooler than the gas that entered the tube through the inlet nozzles.

  

  

Cross Section Sketch of What is Going on Inside

Here is a crude hand sketch I did of what is going on inside. The gas is going into the tube on the left hand side of the drawing through the holes labeled Inlet Air. The green spiral shows the gas swirling to the right where it runs into a conical shaped block that can be adjusted in and out of the tube. When it hits the cone the hotter gas is siphoned off around the outside of the cone and the cooler continues to spin back down the inside in the other direction. When the cooler gas makes it back to where the nozzles are it reaches an orifice in the tube that allows the cooler gas to exit out the left side in the drawing. The orifice is there to let the cold gas out but also to facilitate getting the inlet gas swirling and traveling in the correct direction (to the right in the picture). Adjusting the cone shaped block in and out allows you to adjust the ratio of how much air is going out each end of the tube - balancing the flow - and changing the temperature difference between the hot and cold ends.

To build my vortex cooling tube I used PVC pipe that has an inner diameter of about 0.81 inches. Looking into the formulas for the design of a "real vortex cooling tube" you usually want the length of the Hot End of the tube to be about 45 times the diameter or in my case about 36.5 inches. So this is the length in the drawing above from the inlet nozzles to the cone block valve. In keeping with that thought here are some other dimensions that I followed in making my tube:
  

Tube I.D. = 0.81"

Hot End Length = 45 x 0.81 = 36.5" (round off a bit)

Cold End Length = 10 x 0.81 = 8 (round off a bit here too)

Orifice Size = 1/2 Tube I.D or about 0.40 inches (ballpark rounding of slide rule accuracy)

Inlet Nozzles = 0.12" and I drilled 5 of them

  

Vortex Chamber

A close up view of the "vortex chamber" as I like to call it - this is where the Inlet Nozzles and the Orifice are. To make this part of it I took a piece of PVC tube and cut it to make the Hot End Length and the Cold End Length to the dimensions above. (Scroll down to a hand drawn picture of a cross section when reading this part to help see what I'm explaining) Then I got a thin piece of plastic and cut it into a circle the same diameter as the Outside of the 0.81 I.D. PVC tube -  the outside diameter was about 1.05 inches (so 1 inch tube). I drilled a hole in the plastic about 0.40 diameter to make the orifice. I then got a 1" PVC pipe tube coupling and filed and sanded the inside so that the PVC pipes will slide all the way through. I slid the Hot and Cold tubes into this coupling capturing the cold Orifice plate in between - no glue at this point.
  

Orifice Plate

Above is a picture looking down the cold end of the tube at the orifice plate. You can see the 0.40 diameter hole. I marked the Hot and Cold tubes as well as the coupling so I could take it apart and put it back together in the same orientation.... then I took it apart and glued in the hot tube only. Next I drilled 5 holes through the coupling and into the tube at an angle (tangential) as close to the end of the Hot tube as I could.

  

  
Actually I had my assistant Otto Jr. help me drill the holes! The drilling was made easier bu starting the holes with an Exacto knife.
 

  
UPDATE 8/28/10: I have added some videos explaining how I built this HERE
Check it out!
  

So now the two 1/4" cut pieces (red in the picture above) form the ends of a chamber labeled Inlet Air Area with the large 2" pipe coupling making the outside (Purple). All this is to have one inlet fitting for the air to go into the Inlet Air Area and from there it can make it into the 5 Inlet Nozzles. I could have had just one inlet nozzle or have five air lines into each hole but the method above works better and is super fun to make! I drilled one hole in the outer coupling and screwed a 1/4 Tube X 1/4 NPT fitting into the PVC plastic. I applied a lot of PVC glue and drilled the hole small so the fitting cut it's own threads going in.

  

Now onto the other end of the vortex cooling tube. The cone block I turned down on my homemade lathe and glued a bolt into it. The bolt threaded into the end of a DeStaCo clamp that was run through a PVC pipe plug. I cut a notch in the tube to let the hot air out and drew graduations on the cone to get an idea of how much adjustment I'm getting when I move the red lever.
  

Here is the cone block valve installed in the end of the tube.

  

That's about all there is to it! I attached an air hose to the tube fitting I screwed into the side, put on my safety glasses and turned on the compressor. These things make a lot of noise and get pretty warm / cold on their respective ends.

   
Be sure to take a look at THIS link to see some of the other Vortex Tube related things (and other stuff) that I have built.
   
For another cool version of a D.I.Y. Ranque Hilsch Vortex Cooling Tubes and lots of good information click HERE