Vortex Tubes: What, Why, Where?

The most common questions about Vortex Tubes are “How long have they been around?” and “How do they work?”. These questions are simple enough and answering someone how long Vortex Tubes have been around is the easy answer, Vortex Tubes have been around since 1928 with what may seem as an accidental existence by the developer George Ranque.

As to how they work, these are a phenomenon of physics and the theoretical math behind them has yet to be proven and set in stone. They have been called various names such as “Maxwell’s Demon” which posited that a demon was splitting the hot and cold air molecules prior to leaving the Vortex Tube.  They have also been referred to as  the “Ranque Vortex Tube”, “Hilsch Tube”, and the “Ranque-Hilsch Tube” which highlight some of the prominent people in developing vortex tubes. 

WHAT: EXAIR defines a Vortex Tube within our catalog as “a low cost, reliable, maintenance free solution to a variety of industrial spot cooling problems. Using an ordinary supply of compressed air as a power source, vortex tubes create two streams of air, one hot and one cold, with no moving parts.”

The scope of Vortex Tubes include being able to produce temperatures from -50 degrees to 260 degrees Fahrenheit with flow rates from 1 to 150 SCFM and refrigeration up to 10,200 Btu/hr. Temperatures, flows and cooling power can be easily adjusted with the control valve located on the “hot” end of the tube.

WHY: EXAIRs’ Vortex Tubes offer low cost and reliable solutions primarily for product cooling and sometimes heating. Constructed of stainless steel, our vortex tubes are resistant to corrosion and oxidation providing for years of reliable maintenance-free operation. Vortex tubes operate with a source of compressed air with no moving parts or electricity.

EXAIR offers two series of vortex tubes. The 32XX series is “Maximum Refrigeration (cooling) and is typically used for process cooling, part cooling or chamber cooling. The 34XX series provide lowest cold temperatures at low cold airflow and typically used in cooling lab samples and circuit testing.

EXAIR offers a cooling kit with interchangeable generators that are easily changed so you can experiment and find what temperature and airflow works best for your application.

WHERE: There are many uses for EXAIR Vortex Tubes including but not limited to cooling electronics, machining operations, CCTV cameras, soldered parts, gas samples, heat seals, environmental chambers, ultrasonic weld horns, welds and setting hot melts.

The history of EXAIR Vortex Tubes and the variety of uses has derived new products designed for specific applications like our Spot Coolers and Cabinet Coolers. These items can be found in our catalog or at www.EXAIR.com.

If you have any questions regarding these products or any products that EXAIR offers I hope to hear from you.

Eric Kuhnash
Application Engineer
E-mail: EricKuhnash@exair.com
Twitter: Twitter: @EXAIR_EK

Vortex Tubes: What is a Cold Fraction?

Have you ever needed a source of cold air but don’t want to invest in a costly chiller? INTRODUCING Vortex Tubes! Vortex Tubes use compressed air and contain no moving parts to create a cold and hot stream of air from either end of the device. Using the valve located on the hot stream a vortex tube can achieve temperatures as low as -50°F (-46°C) and temperatures as high as 260°F (127°C).

When the vortex tube is supplied with compressed air the air flow is directed into the generator that causes spin into a spiraling vortex at around 1,000,000 rpm. This spinning vortex flows down the neck and wall of the hot tube. The control valve located on the end of the hot tube allows a fraction of the hot air to escape and what does not escape reverses direction and travels back down the center of the tube and exhausts out of the cold end. Inside of the low-pressure area of the larger outer warm air vortex, the inner vortex loses heat as it flows back to the cold end of the vortex and as it exits the vortex expels cold air. The absolute temperature drop that occurs during this process is going to be controlled by the cold fraction of the Vortex Tube and the supply pressure.

The brass screw used to control the cold fraction of a vortex tube

The cold fraction is defined as the amount of the inlet supply air that will exit out of the cold end of the vortex tube. An example would be if I had 10 SCFM supplied to a vortex tube with 60% cold fraction, then 6 SCFM would be exiting the cold discharge. Cold based on the amount of air you allow out of the hot end of the vortex tube you can control the temperature drop of the cold air. A smaller cold fraction which only allows a small amount of air to exit the cold discharge will result in a larger temperature drop; and vise versa a larger cold fraction will result in a much smaller temperature drop.

Table the shows the temperature drop and rise in correlation with the cold fraction and pressure

Here a EXAIR we have designed our vortex tubes to operate optimally at both a high cold fraction and a low cold fraction. The 32XX series designed to give you the best refrigeration, which means it will work well for cold fractions ~60% – 80%. This will give you a smaller temperature drop with more air flow which allows you to keep things cool much easier. This contrasts with the 34XX series which is designed more optimal performance at lower temperatures; this means the optimal cold fraction would be ~20% to 40%. Cold fractions this low will produce very little air flow but the temperature will be very cold (as low as -50°F). This is useful if you need to get an item down to a very low temperature.

If you have any questions about compressed air systems or want more information on any of EXAIR’s products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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Tried and True Products with Modern Performance and Safety Features

Over Labor Day I got the chance to take my dad and his friend climbing in Seneca Rocks West Virginia for the first time in a very long time. Seneca Rocks is a large Quartzite knife edge located in the Monongahela National forest on route 33. The majority of climbing there is what is known as Trad Climbing, which is just short for traditional climbing and is where one must place their own protection to clip the rope into (also pray it holds when you fall). Trad climbing requires a strong mental fortitude and precise physical movements as you jam different parts of your body into various sized cracks.

Me on the left and my Dad’s friend at the trail head for the hike to “the walls”.

In the ever-expanding world of new technology and advancements of outdoor adventure gear, all trad climbers stick with the same gear that was used some 30+ years ago. Although the materials and performance have improved the very principle and mechanics behind them has not. In this case the old saying “If it ain’t broke don’t fix it!” rings true. Sometimes when it comes to a solution, whether its hanging 200’ in the air or updating a process line, traditional is a great choice due to its simplicity and effectiveness.

Compressed air has been around since 1799 but the idea has been around since 3rd Century B.C. making it one of the oldest utilities next to running water. When it comes to manufacturing applications it’s about as tried and true as you can get, so why not look into our engineered products to help you solve your issues. Their simplicity and effectiveness remain, while their efficiency, safety and performance have been engineered to modern day needs.  These modern needs have insisted that products be safer and more efficient then they were 30+ years ago.  

One example of this is EXAIR’s Vortex Tube. Vortex tubes where discovered in 1931 and were exposed to industrial manufacturing in 1945. EXAIR improved upon them when the company began in 1983. Today they are still used for various cooling applications such as replacing mist coolant on CNC machines, cooling down plastic parts during ultrasonic welding, and keeping electrical cabinets cool so they don’t overheat.

Another example is air nozzles, nozzles are used for many different purposes like cleaning or cooling parts. If you are using nozzles from 30 years ago because they are effective, there is a good chance you can improve you r efficiency and increase safety for your personnel with EXAIR’s engineered Super Air Nozzles. They are designed in a variety of styles to fit your needs from tiny micro nozzles to massive cluster nozzles to blow off or cool  a multitude of parts and processes. 

Sub-zero air flow with no moving parts. 3400 Series Vortex Tubes from EXAIR.

If you have any questions about compressed air systems or want more information on any of EXAIR’s products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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Battling Heat Transfer

If you haven’t read many of my blogs then this may be a surprise. I like to use videos to embellish the typed word. I find this is an effective way and often gives better understanding when available.  Today’s discussion is nothing short of benefiting from a video.

We’ve shared before that there are three types of heat transfer, more if you go into sub-categories of each. These types are Convection,  Conduction, and Radiation. If you want a better understanding of those, feel free to check out Russ Bowman’s blog here.  Thanks to the US Navy’s nuclear power school, he is definitely one of the heat transfer experts at EXAIR.  If you are a visual learner like myself, check out the video below.

The Application Engineering team at EXAIR handles any call where customers may not understand what EXAIR product is best suited for their application. A good number of these applications revolve around cooling down a part, area, electrical cabinet, or preventing heat from entering those areas.  Understanding what type of heat transfer we are going to be combating is often helpful for us to best select an engineered solution for your needs.

Other variables that are helpful to know are:

Part / cabinet dimensions
Material of construction
External ambient temperature
If a cabinet, the internal air temperature
Maximum ambient temperature
Desired temperature
Amount of time available
Area to work with / installation area

Understanding several of these variables will often help us determine if we need to look more towards a spot cooler that is based on the vortex tube or if we can use the entrained ambient air to help mitigate the heat transfer you are seeing.

If you would like to discuss cooling your part, electrical cabinet, or processes, EXAIR is available. Or if you want help trying to determine the best product for your process contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

Video Source: Heat Transfer: Crash Course Engineering #14, Aug 23, 2018 – via CrashCourse – Youtube – https://www.youtube.com/watch?v=YK7G6l_K6sA