EXAIR Vortex Tubes are for a Variety of Cooling Applications

Vortex tube
Cooling or Heating with the Vortex Tube

EXAIR Vortex Tubes are a low cost, reliable and maintenance free solution to a wide variety of industrial spot cooling problems.  They only requirement is a supply of compressed air as the power source.  Vortex Tubes have no moving parts and can produce temperatures that range from -50°F to +260°F (-46°C to +127°C).

Vortex Tubes produce two air streams one cold and one hot, the percentage of cold air flow from the inlet flow is referred to as the cold fraction.  The cold fraction is adjustable by the hot valve on the hot discharge side of the vortex tube.  Adjusting the hot valve results in both air temperature and air volume changes. The colder the air becomes, the volume of that cold air declines. So for very cold temperatures, a smaller volume of air is produced compared to a warmer air temperature.

For the vast majority of industrial cooling applications a larger volume of cool air will provide more efficient cooling than a lesser amount of very cold air.  Generally speaking the highest Btu/Hr values are in the 70-80% cold fraction range.

The exception to this would be in labs or special cases where the coldest temperatures are desired.  Adjusting a Vortex Tube is easy, simply insert a thermometer/thermocouple in the cold air exhaust and set the temperature by adjusting the valve on the hot end of the Vortex Tube.  You will know when you reach max refrigeration (80% cold fraction) as the cold air temperature will be 50°F (28°C) lower than the compressed air supply temperature.

EXAIR Vortex Tubes are constructed from stainless steel.  This ensures excellent wear resistance, corrosion resistance and assures years of reliable operation.  They are offered in 3 different size ranges (small, medium & large).  There are generators located inside the tube (user serviceable) that will change the volumetric flow.  The generators are available in a plastic construction or brass construction for high temperature applications.  The ranges 2 SCFM – 8 SCFM are designated as small Vortex Tubes, 10 SCFM – 40 SCFM are medium and 50 SCFM – 150 SCFM are large.  This feature allows you to customize or change your Vortex Tube for greater flexibility in a wide range of applications.

vortex_generator
Vortex generator

Large Vortex Tubes are specified when a high flow of cold air is needed. There are 16 models to choose from in total.  Capable of providing 3,400 BTU/HR up to 10,200 BTU/HR of cooling power.  These have been used to cool high heat loads that are centrally located or to help cool samples of gases for testing.

Medium Vortex Tubes are the most popular – there are twenty to choose from, depending on the cold air flow rate and temperature you’re looking for. These can produce temperatures as cold as -40°F (-40°C) when set to a 20% Cold Fraction (which is the percentage of total supply air that’s directed to the cold end) and cold air flows as high as 32 SCFM when set to an 80% Cold Fraction, which will produce a cold air temperature of about 20°F (-7°C). Some common uses are cooling ultrasonic welds and brazed joints.

The Medium Vortex Tubes are so popular, in fact, that they’re incorporated into our Adjustable Spot Cooler and Cold Gun Systems. They come ready-to-go with mufflers, cold air hose kits, and magnetic bases, so they couldn’t be easier to use.

Adjustable Spot Cooler

Cold Gun Lineup

Small Vortex Tubes are great when low flows (less cooling power) will succeed, or if compressed air supply is limited.  There are 12 models in total to choose from. These are specified for much smaller applications, like cooling the needle of a sewing machine, small drill bits, etc. You can also get one with a cold air hose & magnetic base…that’s the Mini Cooler System.

Mini Cooler

If you would like to discuss Vortex Tubes, Spot Cooling, efficiency of your compressed air usage, quieter compressed air products and/or any EXAIR product,  I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer
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Keep Small Parts Cool with EXAIR’s Mini Cooler

As they always say, “big things come in small packages”. Oftentimes, some of the things that have the most value or quality are quite small. Jewelry or diamonds certainly come to mind as some high-quality items that are relatively small in size. One little product we have at EXAIR is the Mini Cooler. Don’t let the word “Mini” fool you. EXAIR’s Mini Cooler packs a powerful punch while using minimal compressed air and not taking up valuable space on your shop floor.

minicoolerWFAM_500
Single and Dual Point Mini Cooler

The Mini Cooler is a proven, reliable way to reduce downtime and increase productivity on a wide variety of operations involving small parts where heat is causing a problem. With just an ordinary supply of compressed air as the power source, the Mini Cooler uses Vortex Tube technology to produce a 20°F (70°F compressed air temp) stream of cold air. This cold air can be directed to the part to prevent heat build-up that can cause premature tool wear, affect part tolerances and improve product finish. The Mini Cooler consumes just 8 SCFM of compressed air when operated at 100 PSIG, making it an ideal solution when available compressed air is at a premium.

The Mini Cooler can be used for a wide variety of applications, many of which we’ve blogged about here before. This application discusses a manufacturer that made surf casting bags used by fishermen fishing straight off of the beach. They had problems with the needle overheating and breaking which in turn damaged the finished product. Not only were they wasting materials, but also time spent periodically replacing the needles on the sewing machines. A focused stream of cold air from the Mini Cooler was all it took to remedy the situation.

Another application that I had the pleasure of seeing while visiting in Hungary was at a manufacturer of cataract lenses. They were using both the Adjustable Spot Cooler and the Mini Cooler in the milling process of the lenses. The cold air from the Mini Cooler replaced expensive and messy liquid coolant and was capable of maintaining a consistent temperature on the lens to prevent warping.

IMG_1951
Mini Cooler used to maintain a low temperature on cataract lenses during inspection.

The Mini Cooler is available with both single and dual cold outlets, depending on the part needing to be cooled. The kit will include the Mini Cooler, a swivel Magnetic Base for precise mounting and positioning, either a Single or Dual Point Hose Kit, and a Manual Drain Filter with a mounting bracket included. If you’re experiencing heat related troubles on a small application, take advantage of EXAIR’s Unconditional 30-Day Guarantee and give the Mini Cooler a try. You’ll be HEATED if you don’t!

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@exair.com
Twitter: @EXAIR_TD

Adjustable Spot Cooler Provides Needed Cooling In Sunglass Lens Manufacturing

A little while back, I worked with a large eyeglass manufacturer on a sunglass lens cooling application. In their setup, they were dry cutting film-coated lenses with a router and after the lenses are cut, they are passed through several different rinse cycles and inspected for scratches or other damage. They were seeing a high number of reject parts and determined that the heat being generated by the tooling, was causing the irregularities. In an effort to alleviate the condition, they used a section of open flexible tubing to blow compressed air at the bit, which helped a little, but they were still concerned with the amount of scrap material.

I recommended they use our Model # 3825 Adjustable Spot Cooler System in the process. The Adjustable Spot Cooler incorporates a Vortex Tube to provide a temperature drop from the incoming supply air temperature. Using the temperature control valve, the exhausting air temperature and flow can be adjusted to fit the application. The system includes a flexible hose to focus the cold air to the desired area until re-positioned. The system also features a magnetic base that allows for easy mounting. By incorporating the filter separator included in the system, they can remove any moisture and/or contaminants in the air supply, relieving any concern with contamination or damage to the part.

Model 3825 Adjustable Spot Cooler System

If you have a cooling application you’d like to discuss or for help selecting the best product to fit your need,  give me a call at 800-903-9247.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

sunglasses image courtesy of passer-by via creative common license.

 

When Efficiency And Practicality Collide

Even if you’re a casual reader of our blogs, you already know that EXAIR Application Engineers LOVE to preach efficiency in the use of compressed air…it’s our “bread and butter;” the very nature of our business. This year, we’re celebrating thirty-five years of leading the way in the development of efficient, safe, and quiet compressed air products. Our track record of success as a solutions provider across a diverse range of industrial and commercial applications is well documented in our blogs, as well as Knowledge Base and Case Study Libraries.  We devote considerable resources (engineering, research & development, product testing, etc.) to making certain that EXAIR Intelligent Compressed Air Products cost less to operate, and perform better, than whatever you’re using right now.

Strange as it may seem, though, sometimes our products are EXTREMELY popular in cases where they INCREASE a facility’s consumption of compressed air…by replacing something that DOESN’T use compressed air at all:

*I’ve written before about how our Large Maximum Cold Temperature Vortex Tubes have replaced liquid nitrogen rigs in freeze sealing operations.  Now, a Vortex Tube directs a portion of its air supply to (usually) unusable hot exhaust, in order to generate the usable flow of cold air.  When compared to the costs of liquid nitrogen and the resources involved to get it where it needs to be, though, the cost of the compressed air needed to operate the Vortex Tube is indeed the practical solution.

A 1/4 ton of refrigeration from a product that fits in the palm of your hand, and all you need is a supply or compressed air!

*Line Vacs are probably THE prime example of the value of using compressed air where it wasn’t used before…replacing a “bucket and ladder” operation:

Straight from our Catalog, a perfect example of using valuable compressed air to save even more valuable resources.

*Then there are the situations that just come down to time.  In large spaces, our Super Blast Safety Air Guns can be used to “sweep” the floor in a fraction of the time it takes an operator with a push broom.

Super Blast Safety Air Gun makes short work of large area cleanup.

To make a long story just a little bit longer…if you’re using compressed air, you can use it better with EXAIR’s engineered compressed air products.  And there are plenty of practical applications where you’re not using compressed air right now too.  If you’d like to find out more about either one, give me a call.

Russ Bowman
Application Engineer
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How Versatile Are EXAIR Compressed Air Products?

I wish I could quantify that, but we keep finding more and more applications for them:

Vortex Tubes are used all the time for cooling applications, down to MINUS 40 degrees (Fahrenheit OR Celsius…that’s the point where they’re both the same; no math required.) They also produce a HOT air flow, which we usually call “exhaust,” but some users actually use IT for heating, and call the COLD flow the “exhaust.”

The EXAIR Vortex Tube. Cold air from one end; hot air from the other. Fully adjustable. You can use either...it's fine with us; whatever you need.
The EXAIR Vortex Tube. Cold air from one end; hot air from the other.  You can use either…it’s fine with us; whatever you need.

Our E-Vac Vacuum Generators are popular for “pick-and-place” jobs…hook one up to a Vacuum Cup and you can move parts around all day long. One time, though, I helped a

customer who needed to “pick-and-place” individual small pieces of woven fabric, a lot like a coffee filter. Even our smallest E-Vac, supplied from a Pressure Regulator cranked all the way down, was too much…it would still pick up most of the stack. We found they could use a Model 120020 3/4″ Super Air Amplifier just fine…the Pressure Regulator was still cranked all the way down, and it picked them up one at a time.

No matter what you need to pick-and-place, we've got you covered.
No matter what you need to pick-and-place, we’ve got you covered.

Our Super Air Knives are perfect for blow off, drying, and cooling applications…whether you’re trying to rid your product of dirt/debris, water, or heat, a laminar curtain of adjustable air flow is a “textbook” solution. But I recently had the pleasure of helping a customer who needed to KEEP SOMETHING IN PLACE and called to ask about an Air Knife. They had small cups running single-file down a conveyor belt, with an overhead brush roller pushing down on them at one point so they could be treated on one side. Without something holding them in place, the tooling would simply push them off the side of the conveyor. It required frequent adjustment because they run different sized cups…and they almost always lost some cups when they switched to a different size, while “dialing in” the brush tension. By installing a Model 110036 36″ Aluminum Super Air Knife in place of the brush, they can hold any size cup in place with the downward air flow “curtain.” No more lost product when they don’t get the brush adjustment just right!

Continuous, even, fully adjustable curtain of air...EXAIR Super Air Knives come in lengths from 3 inches to 9 feet.
Continuous, even, fully adjustable curtain of air…EXAIR Super Air Knives come in lengths from 3 inches to 9 feet, in stock.

If you have a compressed air application you’d like to discuss, give me a call.  Perhaps we’ll find the next level of versatility!

Russ Bowman
Application Engineer
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Real Heroes of Science: Rudolf Hilsch

Rudolf Hilsch helped to advance vortex tube technology into what it is today.

If you look into the history or even the definition of a vortex tube, you’re likely to find mention of a physicist named Rudolf Hilsch.  Born December 18th, 1903, Hilsch was a German physicist, professor, and manager of the Physics Institute of the George August University of Göttingen.  He received a doctorate degree by the age of 24 and spent his career furthering the advancement and understanding of numerous phenomena of physics.

Although Hilsch didn’t invent the Vortex Tube (the original inventor was a physicist by the name of Georges J. Ranque), he is entwined with their history thanks to a paper he published in 1947.  According to lore, this paper significantly changed the understanding and performance capabilities of the vortex tube, eventually being marked as the precursor for identifying a vortex tube as a real potential cooling device. (I’ve made attempts to find this 1947 publication properly translated into English, but to no avail.  If you have it or find it, please email it to me at LeeEvans@EXAIR.com! (Original publication in German can be found here.)

Given that vortex tubes are a known EXAIR solution, it seems reasonable that today, on Hilsch’s birthday, we give recognition to this influential physicist and his mark on thermodynamic fluid flow technology.  And, although we at EXAIR are connected to Hilsch through vortex tubes, everyone alive has been influenced by his work.  This is because Hilsch and a partner (physicist Robert Wichard Pohl) constructed the first semiconductor amplifier in 1938, prompting Hilsch to prove (in 1939) that solid-state electronics are possible.  This work paved the way for transistor and solid-state electronics technology as we know it today.  Without Hilsch and his life’s work, not only would we not have vortex tubes, we likely would have any electronic devices we use every day.

Here’s to you Rudolf Hilsch.  Thank you for your work, your discoveries, and your achievements.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

 

 

Intelligent Compressed Air: How do Vortex Tubes Work

A vortex tube is an interesting device that has been looked upon with great fascination over the last 89 years since its discovery by George Ranque in 1928. What I’d like to do in this article is to give some insight into some of the physics of what is happening on the inside.

With a Vortex Tube, we apply a high pressure, compressed air stream to a plenum chamber that contains a turbine-looking part that we call a generator to regulate flow and spin the air to create two separate streams. One hot and one cold.

Below is an animation of how a Vortex Tube works:

Function of a Vortex Tube

 

The generator is a critical feature within a vortex tube that not only regulates flow and creates the vortex spinning action, it also aligns the inner vortex to allow its escape from the hot end of the vortex tube. Note the center hole on the photo below. This is where the cooled “inner vortex” passes through the generator to escape on the cold air outlet.

Vortex generator

Once the compressed air has processed through the generator, we have two spinning streams, the outer vortex and the inner vortex as mentioned above.  As the spinning air reaches the end of the hot tube a portion of the air escapes past the control valve; and the remaining air is forced back through the center of the outer vortex.  This is what we call a “forced” vortex.

If we look at the inner vortex, this is where it gets interesting.  As the air turns back into the center, two things occur.  The two vortices are spinning at the same angular velocity and in the same rotational direction.  So, they are locked together.  But we have energy change as the air processes from the outer vortex to the inner vortex.

If we look at a particle that is spinning in the outer vortex and another particle spinning in the inner vortex, they will be rotating at the same speed.  But, because we lost some mass of air through the control valve on the hot end exhaust and the radius is decreased, the inner vortex loses angular momentum.

Angular momentum is expressed in Equation 1 as:

L = I * ω

L – angular momentum
I – inertia
ω – angular velocity

Where the inertia is calculated by Equation 2:

I = m * r2

m – mass
r – radius

So, if we estimate the inner vortex to have a radius that is 1/3 the size of the outer vortex,  the calculated change in inertia will be 1/9 of its original value.  With less mass and  a smaller radius, the Inertia is much smaller.  The energy that is lost for this change in momentum is given off as heat to the outside vortex.

Adjustments in output temperatures for a Vortex Tube are made by changing the cold fraction and the input pressure.  The cold fraction is a term that we use to show the percentage of air that will come out the cold end.  The remaining amount will be exhausted through the hot end. You can call this the “hot fraction”, but since it is usually the smaller of the two flows and is rarely used, we tend to focus on the cold end flow with the “cold fraction”.  The “Cold Fraction”  is determined by the control valve on the hot end of the Vortex Tube. The “Cold Fraction” chart below can be used to predict the difference in temperature drop in the cold air flow as well as the temperature rise in the hot air flow.

Vortex Tube Cold Fraction

By combining the temperature drops expressed above with the various flow rates in which Vortex Tubes are available, we can vary the amount of cooling power produced for an application. The above cold fraction chart was developed through much testing of the above described theory of operation. The cold fraction chart is a very useful tool that allows us to perform calculations to predict vortex tube performance under various conditions of input pressure and cold fraction settings.

The most interesting and useful part about vortex tube theory is that we have been able to harness this physical energy exchange inside a tube that can fit in the palm of your hand and which has a multitude of industrial uses from spot cooling sewing needles to freezing large pipes in marine applications to enable maintenance operations on valves to be performed.

We would love to entertain any questions you might have about vortex tubes, their uses and how EXAIR can help you.

John Ball
Application Engineer

Email: johnball@exair.com
Twitter: @EXAIR_jb