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

Spot Cooling, Cold Gun Promotion

Like many companies, here at EXAIR we generally always have a promotional offering.  These rotate throughout the months and this month is no different.  The current offering involves the EXAIR Cold Gun Aircoolant Systems.

These spot cooling systems help to reduce cutting fluid use, increase production speeds, increase tool life, and has helped more customers than I know.  One customer in particular is a maintenance worker from a welded tube manufacturer.  This facility had very little amount of downtime permitted due to the high efficiency and high volume of orders.  When a machine went down the maintenance team went in like a trauma team to determine the cause of failure and get it fixed to get the line back up and running. One of the biggest problems they would have is when they would have to dry machine a quick part to get the machine back up and running, this would either ruin tools or they would have to slow down the machining time to get the surface finish and dimensions they truly needed.  After talking with us the team ordered a Single Point Cold Gun Aircoolant System as these parts were generally small enough to tackle with the single cold outlet (larger parts benefit from the dual point hose kit).

They received the spot cooler system in and sure enough a machine went down.  The crew went to work and once the broken part was located they got to work on their lathe trying to make a new piece.  The Cold Gun held itself straight to the headstock thanks to the integrated magnet and the flexible single point hose kit routed the cold air straight to the cutting insert point.  They didn’t have to fill up the liquid tank or setup the mist system on the lathe, they simply turned on the compressed air and let the lathe do the work.  They were able to take what had recently been around a three hour machine job with heavy wear on tooling to a two hour job, no finish pass was needed on the part, and their tools weren’t completely spent by the end of the job.

They got the part back into the machine, made adjustments, and then went to work getting the machine back into production.

Right now, if you would like to try out a Cold Gun Aircoolant System you can order before 12/31/21 and you will receive a free Dual Point Hose Kit with your qualified purchase.

Dual Point Hose Kit

Jordan Shouse
Application Engineer

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Twitter: @EXAIR_JS

EXAIR Cold Gun Overview

In any machining operation, tool wear is an inevitability. Cutting tools heat up due to friction and this heat contributes to premature tool wear. As tooling wears, poor tolerances and dimensional inaccuracy are common. Additionally, as the cutting edge dulls increased cutting force is required which further increases the amount of heat generated.

Coolants can be used to reduce friction and help mitigate some of the wear, but then you’re left with the mess that coolant brings along with it both on the part and in the machine itself. What if I were to tell you that there’s a way to mimic the effects of coolant, but without all of the mess? All of this can be achieved with just a supply of compressed air and one of EXAIR’s Cold Gun Systems.

EXAIR’s Cold Gun was a Product of the Year finalist in 2007. By using only a source of compressed air, the Cold Gun and High Power Cold Gun produces a stream of clean, cold air 50° (28°C) below your compressed air supply temperature. The Cold Gun is very quiet at only 70dBA and has no moving parts to wear out. Just supply it with clean, dry compressed air and it’s maintenance free!

Cold Guns Systems

The Cold Gun is pre-set to an 80% Cold Fraction. In other words, 80% of the compressed air supplied to it will exhaust from the cold end of the tube, 20% from the hot end. This prevents the Cold Gun from freezing up during use and optimizes the gun’s cooling capacity. The Cold Gun is an ideal alternative to messy and expensive coolant mist systems. It eliminates the cost of purchase and disposal of cutting fluids as well as worker related health problems from breathing airborne coolant or slipping on wet floors. Replacing a coolant-based system also eliminates the need for secondary cleaning operations after milling or drilling.

The Cold Gun is an invaluable tool for machining a wide range of plastics and other materials that may become contaminated when using traditional coolants or oils. The clean, cold air from the outlet of the Cold Gun keeps the part cool, clean, and dry. Take for example this application where an OEM for the plastics industry uses EXAIR Cold Guns in place of a coolant system.

If you have an application that you believe would be better served by the use of an EXAIR Cold Gun, give us a call. Get one on order today and take advantage of our limited time promotion and receive a FREE Dual Point Hose Kit upgrade!

Tyler Daniel, Application Engineer

E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_TD
Ph. 1-800-903-9247 or 1-513-671-3322

EXAIR Cold Gun, Different Application, Problem Solved!

Recently I was working with a customer on sizing a EXAIR Cabinet Cooler when I found out they would be best suited by another EXAIR product! They wanted to cool some analyzer panel fins (heat sinks) while keeping dust off of them. This application said Cold Gun all the way!

I recommended our Model # 5315 Cold Gun Aircoolant System with two cold outlets. The Cold Gun produces a 50°F temperature drop from compressed air supply temperature and provides 1,000 Btu/hr. of cooling capacity. For example, if your compressed air supply temperature is 70°F you would effectively see 20°F air being discharged from the cold exhaust. The Dual Point Hose Kit splits the cold airflow into 2 separate streams, providing for a wider coverage area.

5315_SCGdual
Model # 5315 Cold Gun System with dual point hose kit

The customer decided to order a single unit and after a week of testing replied back…

“We tried one a week ago with excellent results! We are installing three more today. 

Thank you so much for your help! Our analyzer is running 31°F cooler than it had been with no more overtemp failures!”

It goes without mentioning, but this is the type of positive feedback we are thrilled to hear! It feels incredible when a customer takes time out of their busy schedule to acknowledge how EXAIR products provided the perfect solution for their needs!

BUT the story doesn’t end there… just last week, over 2 months since our last correspondence, the customer sent me another email that read…

“Just a follow up on the effectiveness of the cold air guns. We have not experienced a single failure of our TOC analyzers since the guns were installed two months ago.

The cold air solved the problem of our analyzer overheating — even during the hottest part of the summer.

Thank you for your excellent recommendation!”

I let the customer know how much we appreciated the awesome news and how happy we were to be able to solve their problem. At the end of the day, that’s what we strive for, to provide the best and largest selection of Intelligent Compressed Air Products on the market today.

Jordan Shouse
Application Engineer

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Twitter: @EXAIR_JS