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

Hazardous Locations need Cabinet Cooling too!

Hazardous Locations are a tricky opponent for electrical panels and controls. To safely be in a HAZLOC they either have to be rated for that Environment or they need to be enclosed in a Cabinet that is purged and pressurized to keep any explosive gases, fumes, or dusts out of the Cabinet. This is no new thing, however as the Industrial revolution 4.0 continues to grow and progress products are continually being added to HAZLOC areas. For example, robotic controls, analyzers, motors and switch gears now use electronic accessories to meet the needs for, speed, process control and energy efficiency, which often renders the equipment unsuitable for use in hazardous locations.  While the demand for these new devices continues to grow, not all of these items are able to be made intrinsically safe. And the items that are not will need to be enclosed in a cabinet where heat will build and you need to manage that heat load while retaining the positive pressure a purge and pressurization is putting on the panel.
EXAIR HazLoc Cabinet Cooler Systems are rated for Class I Div 1 & 2, Class II Div 1 & 2, and Class III environments.
First, we need to know what Class, Division, Group and Temp Code your area falls in. Area Classification Methods  The NFPA (National Fire Protection Association) establishes area classifications using three factors. Identified as Classes, Groups and Divisions, these factors are combined to define conditions of specific areas. Class Ratings – Classes are used to define the explosive or ignitable substances that are present in the atmosphere. Class I – Flammable gases or liquid vapor. Class II – Ignitable metal, carbon or organic dusts. Class III – Ignitable fibrous materials. Division Ratings – Divisions are used to define the degree of hazard by determining the explosive or ignitable substance’s expected concentration in the atmosphere. Division 1 – Contains substances under normal conditions Division 2 – Contains substances under abnormal conditions Group RatingsGroups are used to define substances by rating their explosive or ignitable nature, in relation to other known substances. TYPICAL CLASS I SUBSTANCES Group A – Acetylene Group B – Hydrogen or > 30% Hydrogen by Volume Group C – Ethyl Ether & Ethylene Group D – Acetone, Ammonia, Benzene & Gasoline TYPICAL CLASS II SUBSTANCES Group E – Aluminum, Magnesium & Alloys Group F – Carbon, Coke & Coal Group G – Flour, Grain, Wood, Plastic & Chemicals Temperature Class – A Temperature Class is a term that is allocated within a hazardous area or zone to instruments and equipment. The classification or rating signifies the levels of thermal energy allowed in a particular area or produced by specific equipment. EXAIR products are Able to be used in locations at or lower than T3C. EXAIR Cabinet Cooler Systems are available, from stock, to suit most any electric/electronic panel heat protection need:
  • Cooling capacities from 275 to 5,600 Btu/hr. Call me if your heat load is outside this range…we can look at customized solutions too.
  • NEMA 12 (IP54), 4, or 4X (IP66) ratings.
  • Thermostat Control – Standard, or Electronic Temperature Control.
  • Non-Hazardous Purge for contaminant exclusion on less-than-ideally sealed enclosures.
  • High Temperature models for ambient temperatures from 125°F (52°C) to 200°F (93°C).
  • Side Mount Kits when space is limited above the panel.
  • 316SS construction for particularly aggressive environments.
  • UL Classified for hazardous locations,
    • Class 1 Div 1, Groups A,B,C and D
    • Class 2 Div 1, Groups E,F, and G
    • Class 3
    • Temp T3C
When choosing products for use in classified areas, it’s critical to ensure safety through compliance, and the HazLoc Cabinet Cooler Systems allow you to do that, with simplicity and reliability.  If you’d like to discuss an enclosure cooling application, in or out of a classified area, give us a call. Jordan Shouse Application Engineer Send me an Email Find us on the Web  Like us on Facebook Twitter: @EXAIR_JS

Cabinet Coolers: How to Determine Heat Loads

As summer continues, electrical panels will continue to overheat and cause problems within your process lines.  Freon-based coolers can be less effective in higher ambient conditions; and opening the electrical panels to have a fan blow inside creates a dangerous hazard.  The electrical industry states that for every 10oC rise above the operational temperature, the life of an electrical component is cut in half.  To reduce loss in production and premature equipment failures, it is important to keep electrical components cool.  The EXAIR Cabinet Cooler Systems are designed to do just that. 

From right to left: Small NEMA 12, Large NEMA 12, Large NEMA 4X

To find the correct type and size, we need some information about your electrical panel.  EXAIR makes it easy with the Cabinet Cooler Sizing Guide.  This sheet goes over the important details to find heat loads, proper NEMA type, and options for easy installation.  With a filled-out form, we can make sure that the correct model is recommended.  First, we have to start with the surface area of the electrical panel.  From here, we can do some heat load calculations to compare it with the proper cooling capacity. 

To properly reduce the temperature internally, we need to calculate how much heat is being generated.  Heat loads come from four main areas; internal, external, fan, and solar.  From these four, we can add them together to get the total heat load.  So, on the hottest day of the hottest month, the EXAIR Cabinet Cooler System will still keep your electronics cool.  Here are some methods to find the information needed for heat load calculations.

Internal Heat Load:  The internal load is the heat generated from inside the electrical panel.  This heat is produced from the inefficiencies of electrical devices.  There are two ways that we can figure out the internal heat load.

Step A: The simplest way is by hanging a piece of metal like a washer inside the panel for about 15 minutes.  We can get an average temperature inside.  In the sizing guide, you can mark the temperature next to “Internal temperature now”.  To calculate the heat load, we will need the external temperature at the same time you measured the piece of metal.  This temperature difference can determine the internal heat load per surface area of the panel.  See the chart below.

Step B:  if you know the electrical components inside that generate heat, a list can be made with volt/amp ratings, or watts.  This is very useful for new panels.  The major devices would be VFD (Variable Frequency Drives), power supplies, UPS, transformers, thyristors, etc.  We can calculate the inefficiency of the electrical components which will give us the internal heat load.

External Heat Load:  To keep the electronics cool on the hottest day, we will need to know the highest external temperature that the panel will see.  This can include the temperature that is near an oven.  This can be marked in the Max External Air Temperature Possible.  We can compare this to the Max Internal Air Temperature Desired.  Most electrical components are designed to operate at 95oF (35oC).   With the same chart as above, you can use the temperature difference to determine the external heat load per surface area of the panel.

Panel Fans:  To control the environment inside the electrical panels, we need to block all openings and vents.  And this will include removing panel fans if they are installed.  The Cabinet Cooler System will blow dry cold air to push out the hot humid air from the electrical panel back through the Cabinet Cooler.  Since we are removing a “poor” cooling device, we still need to add this to the heat that is being removed.  You can either give the diameter of the fan or the flow of the fan. 

Solar Heat Load:  The solar heat is only needed if the panel is located outside without cover and exposed to sunlight.  For this type of heat load, we will need to know the color of the electrical panel.  Lighter colors will not absorb as much heat as darker colors.

Because there is so much information that is critical for proper sizing, EXAIR also created a Cabinet Cooler System Calculator to give you a good recommendation to keep your electronics cool. I gave some examples above on how to find the heat loads.  Electrical shutdowns are expensive and annoying.  If you have interruptions from high internal temperatures, EXAIR Cabinet Coolers are a great solution.  They can be installed quickly and easily.  With no moving parts or costly preventative maintenance needed, they can run for decades in keeping your electronics cool.  For our U.S. and Canadian customers, you will receive an AC Sensor for free, a $65.00 value, as a promotional item from now until the end of August 2022 with qualified purchases.  How can you not give them a try?  If you have any questions about Cabinet Coolers or the Sizing Guide, you can contact an Application Engineer at EXAIR.  We will be happy to help.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

NEMA/UL and IP ratings

From right to left: Small NEMA 12, Large NEMA 12, Large NEMA 4X

EXAIR manufactures Cabinet Coolers to keep your electrical components inside cool.  This will help to stop any costly shutdowns or premature electrical failures due to overheating.  The EXAIR Cabinet Cooler System is a simple device that generates cold air with no moving parts, condensers, or freon.  They are maintenance-free with a long-life cycle; and installation is quick and easy.  But when mounting the system to your electrical panel, you want to make sure that the Cabinet Cooler meets or exceeds the integrity standard for that environment.  There are standards that categorize electrical panels to protect workers, shield the environment, and contain the electrical components. 

Electrical panels come in all shapes, sizes and colors; and can be used in a variety of environments; indoor, outdoor, and even hazardous locations.  Depending on the place and setting, you will need to determine the minimum requirements for the integrity of your electrical panel.  For example, you do not want to use an “indoor only” electrical enclosure for outside areas.  Also, you would not want a standard enclosure to be used in a hazardous area, as it can be very dangerous.  The major organizations that create these electrical standards are NEMA, UL, and IP.  In this blog, I will cover these organizations and how they rate them.

NEMA, or National Electrical Manufacturer Association, and UL, or Underwriters Laboratory, are generally used in North America.  The difference between these two organizations is that the NEMA ratings are self-certifying while the UL requires testing by qualified inspectors, independent of the manufacturer, for compliance.  They use numbers and in some instances letters to indicate the type of environment that the enclosure can operate. EXAIR Cabinet Cooler Systems are UL listed; so, they have been tested and verified.  Currently, there are over 20 different NEMA/UL classifications.  Here is a description by WIKA that shows the different categories for both NEMA and IP.

IP, or Ingress Protection, is an international standard commonly used in Europe and is established by the International Electrotechnical Commission, or IEC.  This organization also allows for self-certification.  They use two digits to define levels of integrity for electrical enclosures against intrusion from foreign bodies and moisture. The first digit ranges from 1 to 6 which specifies the protection rating from solids.  The second digit, which ranges from 1 to 8, specifies the protection rating for ingress of water.  The higher the number, the better the protection.  The combination of these two numbers will give the protection level of the enclosure against dust and water.  There is an equivalence with the NEMA ratings to the IP ratings, but it is up to the preference of the user to verify the protection requirement. 

EXAIR offers three main NEMA types for our Cabinet Cooler Systems which are the most commonly found within facilities. We also offer an additional two types that are designated strictly for Hazardous Locations and are separately certified by UL to meet those standards.

NEMA 12

NEMA 12 (IP54) Cabinet Coolers are rated for dust tight and oil tight. NEMA 12 cabinet coolers are ideal for general industrial environments where no liquids or corrosives are present and are located inside.

NEMA 4

NEMA 4 (IP66) Cabinet Coolers are rated for dust tight, oil tight, splash resistant and indoor/outdoor service. These Cabinet Coolers incorporate a low-pressure relief valve to allow the internal hot air to escape as well as to close and seal when the cooler is not in operation.  This allows for this Cabinet Cooler to maintain the integrity of a NEMA 4 enclosure.

NEMA 4X

NEMA 4X (IP66) Cabinet Coolers offer the same protection as the NEMA 4 but are constructed of stainless steel for food service and corrosive environments.

HazLoc Cabinet Cooler Systems

HazLoc Cabinet Coolers are designed for hazardous locations and are mounted to NEMA 7, 8, and 9 enclosures.  EXAIR catalogs these Cabinet Coolers as NEMA 4 (IP66) or NEMA 4X (IP66) as mentioned above.  But their registration by UL classified is for Class I, Class II, and Class III hazardous areas.  The reason that they do not match the NEMA rating of the hazardous panels is because they require an X-type or Z-type purge system.  In combination, they will not sacrifice the integrity of hazardous electrical panels. 

EXAIR has Cabinet Coolers in stock with a variety of cooling capacities from 275 BTU/hr to 5,600 BTU/hr (69 Kcal/hr to 1,411 Kcal/hr).  We also offer them in 316SS, high temperature versions, and non-hazardous purge.  We do have a Cabinet Cooler System Calculator to help determine the best product for your application.  If you have any additional questions, an Application Engineer at EXAIR can assist you.   

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb