Maximum Effort!!! The Two Types of Vortex Tube Generators

I am a fan of just about all things MCU (Marvel Cinematic Universe) and have always found Deadpool to be entertaining. Anytime I see a Max Cold Temp or Max Refrigeration mention when discussing or reading about a Vortex Tube I go to a miniature cut scene where Deadpool is saying Maximum Effort as they are fighting the bad guys in Deadpool 2. Enough about my love for MCU, let’s get more into my nerd love for Vortex Tubes.

When it comes to Vortex Tubes and getting the most out of them, EXAIR are the subject matter experts. If you aren’t sure what a Vortex Tube is or how it works, we’ve blogged about that, today’s blog is going to focus more on why you would select a Maximum Cold Temp vs a Maximum Refrigeration Vortex Tube and what actually changes.

Vortex generator

The difference lies in the generator that is inside the Vortex Tube. The reason to choose between the two lies with the application for the tube. In the event that the tube will be used for spot cooling or cooling a small chamber, Maximum Refrigeration generators are desired because you will generally work at a 50% cold fraction or higher. The maximum refrigeration value possible is achieved under set variables such as operating pressure, cold fraction, and incoming compressed air temperature. To see how these effect the cooling performance, check out our blogs on de-rating a Vortex Tube (Part 1Part 2). The bulk of applications that I have worked on over the 10+ years I have been part of EXAIR utilize the Maximum Refrigeration Vortex Tube because customers desire to get a product, small area, or component below ambient air temperatures and are going to be operating in the 50% to 80% cold fraction area in order to provide the performance needed.

EXAIR Vortex Tube Performance Chart

The other small fraction of applications that really need to get the lowest air temperature; in order to get that small component or spot down to -50°F (-46°C) will utilize the Maximum Cold Temperature generators. These will be the 3400 series Vortex Tubes or the “-C” versions. While max cold temperature models are less common, they regularly solve applications for temperature stress testing parts and freeze seals. Maybe you aren’t sure if the Maximum Refrigeration or Maximum Cold Temp is the one you need. That’s where the Application Engineer Team here comes in, hit us up first, and then we can also showcase just how simple it is to change the generator in a Vortex Tube out and give an idea of how many turns out from closed on the Hot Valve you will be to get close to the performance needed.

It truly is just that simple, no internal moving parts, just change out one internal component, and adjust the Hot Valve. To understand how easy that is, check the video below and you can see how big of a swing one can see with adjustments.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

How to Identify Your Vortex Tube Model Number

Not a day goes by that we don’t receive a call from a customer that is having trouble identifying an EXAIR part. Due to the robust nature of our Vortex Tubes, they can be installed in applications for many years without any maintenance. When the time comes to expand that line, the labels may have worn off, the unit may be covered in grime or oil, or the personnel that originally ordered the product may no longer be with the company. In any case, one of the Application Engineers here at EXAIR will certainly be able to help!

I recently received an e-mail from a gentleman who was suffering from that very problem. They had a Vortex Tube installed in a camera cooling application near a boiler.  The engineer who designed the project was no longer with the company, and they could not determine a Model number or when they had purchased it. They saw the EXAIR sticker, along with our contact information, and reached out for help.

The Vortex Tubes come in different sizes based on the available compressed air supply as well as the level of refrigeration needed. We have Vortex Tubes for max refrigeration that contain our “R” style generators, as well as Vortex Tubes for a maximum cold temperature (cryogenic applications) that contain our “C” style generators. In addition to our standard Vortex Tubes, we also offer models for High Temperature applications. In order to identify the style, you must remove the muffler or cold cap to access the generator installed inside. All standard Vortex Tubes will have a white plastic generator, all High Temperature models will have a brass generator installed inside. While we do include a small circular label that indicates the required SCFM at 100 PSIG, we still must know if it’s a maximum cold temperature or maximum refrigeration style of tube.

Included on the generator there will be a stamp that indicates the cooling capacity and air consumption of the tube. In this case, a plastic generator was found inside stamped with “30-R”. This tells us that it’s a Model 3230.

If you’re considering expanding a current line into other parts of your facility, or perhaps expanding to a new location and need help identifying your EXAIR products; give an Application Engineer a call and we’ll be sure you get the right products on order!

Tyler Daniel, CCASS

Application Engineer

Twitter: @EXAIR_TD

E-mail: tylerdaniel@exair.com

The Vortex Tube, Maxwell’s Demon, Hilsch Tube, Ranque Tube: What Exactly is this Device? How Does it Work?

If I were to tell you that I can take a supply of ordinary compressed air and drop its temperature by 50°F with no moving parts and without any type of refrigerant or electrical connection, you might be scratching your head a bit. That is of course unless you’ve been introduced to the wild world of Vortex Tubes. My favorite product among the EXAIR Product Line, the Vortex Tube, does just that. With an ordinary supply of compressed air as the sole power source, and no moving parts, the Vortex Tube converts that airstream into a hot and cold flow that exits from opposite ends of the tube. No magic, witchcraft, or wizardry involved here. Just physics!

The theory all began in the 19th century with the famous physicist and mathematician James Clerk Maxwell. He suggested that since heat involves the movement of molecules, it could be possible to create a device that could distribute hot and cold air with no moving parts with the help of a “friendly little demon” that would sort and separate the hot and cold molecules of air. Not much was done with regard to this or any further advancement until about 61 years later.

In 1928, a French physics student by the name of George Ranque was conducting some testing on a vortex-type pump he had developed. In this testing, he noticed that warm air was exhausting from one end, while cold air was coming out of the other. He dropped his plans for the pump and begin an attempt to exploit this phenomenon commercially. His business ultimately failed, along with the Vortex Tube theory, until 1945 when a German physicist named Rudolph Hilsch published a scientific paper based on the Vortex Tube.

With so many involved, the tube became known by a variety of different names: “Ranque Vortex Tube”, the “Hilsch Tube”, the “Ranque-Hilsch Tube”, and (my personal favorite) “Maxwell’s Demon”. Over the years, it has gained a reputation as a low cost, reliable, and highly effective method for industrial spot cooling and panel cooling applications. While using the tube as a PC cooler isn’t generally recommended, here’s a great video demonstrating the tube in operation from Linus Tech Tips on YouTube:

So how exactly does this thing work? The truth is no one knows for certain, but there is one commonly accepted theory that explains the phenomenon:

Compressed air is supplied into the tube where it passes through a set of nozzles that are tangent to the internal counterbore. The design of the nozzles force the air to spin in a vortex motion at speeds up to 1,000,000 RPM. The spinning air turns 90° where a valve at one end allows some of the warmed air to escape. What does not escape, heads back down the tube in the inner stream where it loses heat and exhausts through the other end as cold air.

Both streams rotate in the same direction and at the same angular velocity. Due to the principle of conservation of angular momentum, the rotational speed of the inner vortex should increase. However that’s not the case with the Vortex Tube. The best way to illustrate this is in Olympic Figure Skating. As the skater is wider, the spinning motion is much slower. As she decreases her overall radius, the velocity picks up dramatically and she spins much quicker. In a Vortex Tube, the speed of the inner vortex remains the same as it has lost angular momentum. The energy that is lost in this process is given off in the form of heat that has exhausted from the hot side of the tube. This loss of heat allows the inner vortex to be cooled, where it can be ducted and applied for a variety of industrial applications.

This Vortex Tube theory is utilized in basic Vortex Tubes, along with a variety of other products that have additional features specific for your application. EXAIR’s line of Cabinet Coolers, Cold Guns, Adjustable Spot Coolers, Mini Coolers, and Vortex Tubes all operate off of this same principle.

If you’re fascinated by this product and want to give it a try, EXAIR offers an unconditional 30 day guarantee. We have them all in stock and ready to ship as well, same day with an order received by 2:00 ET. Feel free to get in contact with us if you’d like to discuss how a vortex-based product could help you in your processes.

Tyler Daniel, CCASS

Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_TD

Vortex Tubes for Dummies

Vortex Tubes are intriguing. We can obtain such extreme cold or hot air with nothing more than compressed air and the Vortex Tube. We can adjust the temps very easily with the turn of a screw. Before we dive into how to adjust and get the right temps for your application, let me share a diagram of how the Vortex Tube works:

The unique physical phenomenon of the Vortex Tube principle generates cold air instantly, and for as long – or short – a time as needed.

Now that we have seen how it works, we need to define how to make it work for your specific application! First we need to set the cold fraction… Setting the “cold fraction” is all about how cold or hot you need the air to be. When we talk about this cold fraction, we are talking about the amount of the cold air that comes out of the cold side of the Vortex Tube, which also affects the temperature of that cold air. In other words, a 60% cold fraction equals 60% of the input compressed air exiting the Vortex Tubes cold side.

For example, if you are supplying 80 psi to our medium sized Vortex Tube, you will be generating between 10 and 40 SCFM (depending on the size of the generator). Let’s assume for this example that you are using our 3230 Vortex Tube, generating 30 SCFM. At an 80% cold fraction, 24 SCFM (80% of 30) will be flowing out of the cold end of the Vortex Tube. And it will be flowing at a temperature that is 50°F colder than the temperature of the compressed air provided. Yes, that is correct, assuming that your inlet air temp is 72°F, you will be flowing 24 SCFM of 22°F air from the cold end of the Vortex Tube. But what about the other 6 SCFM? Well, that will be flowing out of the hot end at a whopping 252°F. We must take into account both ends of the Vortex Tube. You can see the performance table below.

EXAIR Vortex Tube Performance Chart

Let’s look at one more example of this same Vortex Tube 3230. Let’s assume that we need to heat something up. Assuming that your compressed air is 72°F, and we want to heat something up to 115°F, we need to add 43°F to the temp of the compressed air. We can see in the chart that by supplying 80 psig of compressed air, and a 30% Cold Fraction on the Vortex Tube that we can add 43° to the temp of the air. We know that the cold end will give us 9 SCFM (30% of the overall 30 SCFM) and it will flow at -110°F, or -38°F. But we will reach our 115°F desired temp on the hot end, but that will only be at 21 SCFM. If we still need that higher SCFM, we may need to change the generator (explained below) or increase to a larger Vortex Tube all together.

As you can see from the above performance table, there are many ways to get to your desired temperature, be it hot or cold.

Adjusting the Vortex Tube

Next comes the question of how do we adjust the cold fraction. 1st, let me note that unless specified, these always ship to you set at or close to the 80% cold fraction, but, if you want them set to a precise cold fraction, we can permanently set these for you prior to shipping. As you see in the picture to the left, the slotted valve can be turned to adjust the cold fraction. For precision purposes it is always recommended to use a thermometer to set this where you need it (insert the thermometer into the cold flow of air). As a guide, you should seat the valve softly, and back off an 1/8th, a 1/4, or a 1/2 turn (for the small, medium, and large sizes respectively) to drop approximately 20% on the cold fraction scale.

We offer 3 sizes of Vortex Tubes, small, medium and large. Each size offers 3-5 different interchangeable size generators, with a total offering of 12 stock Vortex Tubes. The size of the generator will determine the BTU/hr, as well as the SCFM generated. See the following table for more details:

There are a few other key details to know about the Vortex Tubes. They do not like back pressure. As you can imagine, the magic that makes these work is spinning the generator inside. If that is slowed down due to back pressure, well, it will hinder the results of the entire Vortex Tube. Many people have air coolers or heaters on their compressed air system, keep in mind that the temps generated by the Vortex Tubes are ± the temperature of the compressed air, so it is important to know the temp of your compressed air.

Vortex Tubes can be very loud. We almost always sell these with the Cold and Hot Mufflers. In order to keep most of them under the OSHA standards for sound, you will want the mufflers. Lastly, as with all of EXAIR’s products, it is recommended to use a pressure regulator with a gauge at the point of use. With the Vortex Tubes, it is imperative if you are looking for an accurate temperature.

If you have any questions about the Vortex Tubes, or any of our intelligent air products, please do not hesitate to reach out.

Thank you for stopping by,

Brian Wages

Application Engineer

EXAIR Corporation
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