## Vortex Tube Cooling: One Vortex Tube, Multiple Targets, Will This Work?

I had this question posed to me the other day. The customer asks, “I have three, small, enclosed spaces that are all within about five feet of each other. I’d like to put vortex tube cooling into each space. Can I do it with one vortex tube or will I have to use three of them?”

Imagine if you will, the cold air output of a single vortex tube being split three ways and ducted into each of these small chambers. While it is definitely technically possible to do, it isn’t always a feasible idea from the point of view of lost cooling power. Also, anytime that you can split up the effect you are trying to create whether that be cooling with a Vortex Tube or blowing off a large target that has many features to it, generally it is better practice to divide the application solution up to be applied over multiple, smaller units rather than one large one.

In this customer’s case, he wanted to save money on the purchase of multiple vortex tubes by purchasing one model 3230 vortex tube and plumbing the cold air output to his three cooling chambers. The problem is that the ambient temperature outside the boxes is rather hot and also contains high humidity. How exactly is this a problem?  You might ask. The problem is in all of the heat lost in cooling down the cold air distribution pipe (the pipe, hose or tube delivering the cold air into the chambers) that lies outside each box. That results in a net temperature gain (higher temperature) of the cold air you are trying to use for cooling the chambers or enclosures. With that lost cooling power, the customer runs a risk of not having sufficient cooling power to offset the heat load in each chamber. There is also the issue of back-pressure being presented to the Vortex Tube itself from the cold air distribution piping. When subjected to back-pressure, vortex tubes will lose their cooling capacity. Finally, there is the problem of getting equal cooling power delivered to each chamber. In this case, the solution of piping cold air to each chamber would cause an un-even distribution of the cold air with the closest chamber receiving the lion’s share of the cooling, leaving the other two under-cooled.

So, what is a better way to do this?  The method I suggested to the client was to use three of our model 3208 (8 SCFM) vortex tubes, allowing for direct connection of the vortex tube cold air output to each chamber. The cold air no longer has to cool down the cold air piping thus leaving more cooling power for each chamber, there is no back-pressure issue, and finally and probably most importantly would be the total air consumed would only be 24 SCFM in this case (3 x 8 SCFM) vs. 30 SCFM with a single larger vortex tube. That is a 20% savings on compressed air use in a straight up comparison. Depending on how many hours a day the system would be used, the difference in purchase price could be made up by lower operating cost in less than a year.

Neal Raker
Application Engineer
nealraker@exair.com