Hilsch-Rankine Vortex Tube Question

[syt0x]

I've searched around the forum and found a couple threads about these Hilsch-Rankine Vortex Tubes and I'm amazed. I'd like to make one for a school project but I have one question after looking at all the plans on the internet. Should the tube be made out of something like PVC which allows the air to be insulated or is it more desirable to use copper or steel tubing which might conduct some of the heat away. I want the highest temperature difference between the two ends if possible so I'm leaning more towards the PVC but I'm looking for advice. I was wondering if someone with more knowledge would be able to help . Thanks!!!

[JPolihronov]

Hello,

if you would like to achieve more heating (at hot exit), the walls should not be allowed to conduct heat. Metal is a good heat conductor, so it should be avoided. Or, if metallic pipe is used, it can be wrapped in thermally insulating coat.

If you would like to achieve best cooling, then the walls should be good thermal conductors, such as metal. Even fins acting as heat sinks can be added. However, it is hard to tell how many degrees of cooling will be achieved just because of heat-sinking the tube. In industry, this is not usually done.

As far as achieving large temperature separation, this depends on the ratio of hot-to-cold mass flow and other parameters. Numerous articles report their own highest delta T for their specific case. To say that the wall material of a vortex tube will determine the delta T would be an oversimplification.

To read further on how the vortex tube cools, feel free to visit my page at
sites.google.com/site/vortextubeeffect/

Regards,
-JP