What is the most efficient way to cool air using a Vortex Tube (Ranque-Hilsch)?

In summary, the paper discusses the optimization theory of the Vortex Tube and states that the initial separation of hot and cold air is complete at the left hand side of the tube. The interaction between the two streams is deemed undesirable and it is ideal for the cooled air to return to the right hand side without any further interaction. The paper also suggests that the process of returning the cold air degrades performance due to unwanted heat exchange between the streams. The first question is whether the actual cooling of the cold stream only occurs during the inward deflection at the far end of the tube. The second question is if it would be better to skim off the cold air in a way that isolates it from the warm stream. Additionally, the paper mentions a
  • #1
Swamp Thing
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Ref: https://s3.wp.wsu.edu/uploads/sites/44/2015/12/VortexTubeOptimizationTheory.pdf

The above paper says that the initial separation of hot and cold air is complete once the flow is partly deflected backwards at the left hand side (HOT) end. See Fig. 1 in the paper.

It also says that the further interaction of the two streams is actually undesirable, and that one would want that process to be like a "weak" or "bad" heat exchanger. So ideally we would want the cooled air (inner stream) to make its way back to the right hand side (COLD) end without any interaction with the outer stream.

So the process of returning the cold air to the right hand side, passing all the way through the tube, actually degrades the performance due to unwanted heat exchange between the inner and outer streams. This idea is elaborated in Fig. 3 of the paper.

My first question is -- is it true that the actual cooling of the cold stream happens entirely during the inward / backward deflection at the far end of the tube, and that all further interaction between the streams is merely an undesired dilution of performance?

Second question -- If the above is true, won't it be better to skim off the cold air in some other way that will keep it more isolated from the warm stream? For example:

1674214767061.jpeg


Or maybe like this:

1674214830497.jpeg
 
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  • #2
Another point of confusion is that some papers talk about a "double circuit vortex tube". For example, Fig. 7 in this paper: https://uhra.herts.ac.uk/bitstream/..._for_Resubmission_Without_Mark.pdf?sequence=1

If the answer to my question #1 in the original post is yes, then the double circuit thing doesn't seem to make much sense. The double circuit concept would only make sense if the cooling happens during the interaction between the two streams along the tube.
 

1. What is a Vortex Tube?

A Vortex Tube, also known as a Ranque-Hilsch Tube, is a mechanical device that separates a compressed gas into hot and cold streams using a vortex motion.

2. How does a Vortex Tube work?

A Vortex Tube works by creating a vortex motion inside a cylindrical chamber using compressed gas. The gas is then forced to rotate at high speeds, causing it to separate into two streams, one hot and one cold.

3. What are the applications of a Vortex Tube?

A Vortex Tube has a wide range of applications, including cooling electronic components, freezing liquids, and separating gases. It is also commonly used in industrial processes such as welding, cutting, and drying.

4. What are the advantages of using a Vortex Tube?

Some advantages of using a Vortex Tube include its simplicity, low maintenance, and lack of moving parts. It also does not require any external energy source, making it energy-efficient and environmentally friendly.

5. Are there any limitations to using a Vortex Tube?

One limitation of using a Vortex Tube is that it has a low cooling capacity compared to other cooling methods. It is also not suitable for large-scale cooling applications. Additionally, the temperature difference between the hot and cold streams may not be very high.

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