James Clerk Maxwell

When most of us think of really smart folks, names like Albert Einstein, Carl Sagan, Stephen Hawking, or Richard Feynman often pop up. It’s interesting that, when THOSE folks thought about really smart folks, one name repeatedly came to mind:

  • “Maxwell’s equations have had a greater impact on human history than any ten presidents.” – Carl Sagan
  • “From a long view of the history of mankind — seen from, say, ten thousand years from now — there can be little doubt that the most significant event of the 19th century will be judged as Maxwell’s discovery of the laws of electrodynamics.” – Richard Feynman
  • “Maxwell is the physicist’s physicist.” – Stephen Hawking
  • “The special theory of relativity owes its origins to Maxwell’s equations of the electromagnetic field.” – Albert Einstein
  • “The work of James Clerk Maxwell changed the world forever.” – Albert Einstein (again)

If you follow the EXAIR blog, you may recall that we’ve written more than a couple of entries on James Clerk Maxwell…here, here, and here, just to point out a few. We, of course, all like to point out a thought experiment that he devised regarding a potential loophole in the 2nd Law of Thermodynamics – a “friendly little demon” that could separate a theoretical chamber of gas (consisting of molecules with different kinetic energies) into two sub-chambers: one with all the faster moving (e.g., higher temperature) molecules, and another with all the slower moving (e.g., lower temperature) molecules.

Fun fact: When Maxwell first proposed this thought experiment in a letter to Lord Kelvin, he called it a “finite entity”. Lord Kelvin (much to Maxwell’s chagrin) started calling it a “demon” and the name stuck.

In what MAY be one of the grandest of coincidences in science, the work of this “finite entity” or “demon” is uncannily similar to that of one of the more interesting compressed air operated devices: the Vortex Tube:

When compressed air flow enters, a spinning motion is imparted by the Generator. When the spinning flow reaches the end of the Vortex Tube, a portion is forced to change directions and continue spinning, in the opposite direction, inside the outer spinning flow. When it does so, it gives off energy in the form of heat. The net result is, the air entering at a given temperature is separated into two distinct air streams: one hot, and one cold.

Now, us compressed air aficionados aren’t the only ones who’ve happened upon latter-day incorporations of Maxwell’s thought experiment. Information theory enthusiasts have implied a correlation with the principle of erasure, and scientists at the University of Oxford designed an experiment with a light-powered gate that seems to validate the idea (“How Maxwell’s Demon Continues to Startle Scientists”, Quanta Magazine, 4/22/2021).

I’ve been with EXAIR Corporation for just shy of eleven years now, and every time I hook up a Vortex Tube in the Efficiency Lab, I still recall the wonder of seeing one in action the first time. Considering that this is a 20th Century innovation (and the information theory & light-powered gate experiments are 21st Century), it’s equally impressive to keep in mind what else was going on in the world when Maxwell devised this thought experiment in 1867:

  • At the beginning of March, Nebraska is admitted as the 37th U.S. State. And at the end of the month, the U.S. finalizes the purchase of Alaska from Russia.
  • Alfred Nobel gets a patent for dynamite in the United Kingdom, in May.
  • The first school for dentistry, the Harvard School of Dental Medicine, opens.

And…in case you were wondering, EXAIR Application Engineers also have a list of folks they consider to be really smart folks. If you’re curious, click here.

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
Visit us on the Web
Follow me on Twitter
Like us on Facebook

James Clerk Maxwell statue photo courtesy of trailerfullofpix & dun_deagh. Creative Commons license.

The History of the Man Behind the Friendly Little Demon

James Clerk Maxwell was born in Edinburgh Scotland on June 13, 1831 and from the age of three years old he was described as have an innate sense of inquisitiveness. In 1839 at the young age of 8 years old James’ mother passed away from abdominal cancer which put the boy’s father and father’s sister-in-law in charge of his schooling. In February of 1842 James’ father took him to see Robert Davidson’s demonstration of electric propulsion and magnetic force; little did he know that this event would strongly impact on his future.

Fascinated with geometry from an early age James would go on to rediscover the regular polyhedron before he was instructed. At the age of 13 James’ would go on to win the schools mathematical medal and first prize in both English and Poetry.

Later in his life James would go on to calculate and discover the relationship between light, electricity, and magnetism. This discovery would lay the ground work for Albert Einstein’s Special Theory of Relativity. Einstein later credit Maxwell for laying the ground work and said his work was “the most profound and the most fruitful that physics has experienced since the time of Newton.”. James Maxwell’s work would literally lay the ground work for launching the world into the nuclear age.

Starting in the year 1859 Maxwell would begin developing the theory of the distribution of velocities in particles of gas, which was later generalized by Ludwig Boltzmann in the formula called the Maxwell-Boltzmann distribution. In his kinetic theory, it is stated that temperature and heat involve only molecular movement. Eventually his work in thermodynamics would lead him to a though experiment that would hypothetically violate the second law of thermodynamics, because the total entropy of the two gases would decrease without applying any work. His description of the experiment is as follows:

…if we conceive of a being whose faculties are so sharpened that he can follow every molecule in its course, such a being, whose attributes are as essentially finite as our own, would be able to do what is impossible to us. For we have seen that molecules in a vessel full of air at uniform temperature are moving with velocities by no means uniform, though the mean velocity of any great number of them, arbitrarily selected, is almost exactly uniform. Now let us suppose that such a vessel is divided into two portions, A and B, by a division in which there is a small hole, and that a being, who can see the individual molecules, opens and closes this hole, so as to allow only the swifter molecules to pass from A to B, and only the slower molecules to pass from B to A. He will thus, without expenditure of work, raise the temperature of B and lower that of A, in contradiction to the second law of thermodynamics.

Here at EXAIR we are very familiar with Maxwell’s “friendly little demon” that can separate gases into a cold and hot stream. His thought experiment, although unproven in his life time, did come to fruition with the introduction of the Vortex Tube.

Vortex Tube a.k.a Maxwell’s Demon

With his birthday being last weekend I propose that we raise a glass and tip our hats to a brilliant man and strive to remember the brilliant ideas that he gave us.

If you have any questions or want more information on EXAIR’s Cabinet Coolers or like 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
Visit us on the Web
Follow me on Twitter
Like us on Facebook

  

Vortex Tube Cold Fractions Explained

Simply put, a Vortex Tube’s Cold Fraction is the percentage of its supply air that gets directed to the cold end. The rest of the supply air goes out the hot end. Here’s how it works:

The Control Valve is operated by a flat head screwdriver.

No matter what the Cold Fraction is set to, the air coming out the cold end will be lower in temperature, and the air exiting the hot end will be higher in temperature, than the compressed air supply.  The Cold Fraction is set by the position of the Control Valve.    Opening the Control Valve (turning counterclockwise, see blue arrow on photo to right) lowers the Cold Fraction, resulting in lower flow – and a large temperature drop – in the cold air discharge.  Closing the Control Valve (turning clockwise, see red arrow) increases the cold air flow, but results in a smaller temperature drop.  This adjustability is key to the Vortex Tube’s versatility.  Some applications call for higher flows; others call for very low temperatures…more on that in a minute, though.

The Cold Fraction can be set as low as 20% – meaning a small amount (20% to be exact) of the supply air is directed to the cold end, with a large temperature drop.  Conversely, you can set it as high as 80% – meaning most of the supply air goes to the cold end, but the temperature drop isn’t as high.  Our 3400 Series Vortex Tubes are for 20-50% Cold Fractions, and the 3200 Series are for 50-80% Cold Fractions.  Both extremes, and all points in between, are used, depending on the nature of the applications.  Here are some examples:

EXAIR 3400 Series Vortex Tubes, for air as low as -50°F.

A candy maker needed to cool chocolate that had been poured into small molds to make bite-sized, fun-shaped, confections.  Keeping the air flow low was critical…they wanted a nice, smooth surface, not rippled by a blast of air.  A pair of Model 3408 Small Vortex Tubes set to a 40% Cold Fraction produce a 3.2 SCFM cold flow (feels a lot like when you blow on a spoonful of hot soup to cool it down) that’s 110°F colder than the compressed air supply…or about -30°F.  It doesn’t disturb the surface, but cools & sets it in a hurry.  They could turn the Cold Fraction down all the way to 20%, for a cold flow of only 1.6 SCFM (just a whisper, really,) but with a 123°F temperature drop.

Welding and brazing are examples of applications where higher flows are advantageous.  The lower temperature drop doesn’t make all that much difference…turns out, when you’re blowing air onto metal that’s been recently melted, it doesn’t seem to matter much if the air is 20°F or -20°F, as long as there’s a LOT of it.  Our Medium Vortex Tubes are especially popular for this.  An ultrasonic weld that seals the end of a toothpaste tube, for example, is done with a Model 3215 set to an 80% Cold Fraction (12 SCFM of cold flow with a 54°F drop,) while brazing copper pipe fittings needs the higher flow of a Model 3230: the same 80% cold fraction makes 24 SCFM cold flow, with the same 54°F temperature drop.

Regardless of which model you choose, the temperature drop of the cold air flow is determined by only two factors: Cold Fraction setting, and compressed air supply pressure.  If you were wondering where I got all the figures above, they’re all from the Specification & Performance charts published in our catalog:

3200 Series are for max cooling (50-80% Cold Fractions;) 3400’s are for max cold temperature (20-50% Cold Fractions.)

Chocolate cooling in brown; welding/brazing in blue.

EXAIR Vortex Tubes & Spot Cooling Products are a quick & easy way to supply a reliable, controllable flow of cold air, on demand.  If you’d like to find out more, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
Visit us on the Web
Follow me on Twitter
Like us on Facebook

The Scientific Legacy of James Clerk Maxwell

On June 13, 1831 at 14 India Street, in Edinburgh Scotland James Clerk Maxwell was born. From a young age his mother recognized the potential in James, so she took full responsibility of his early education. At the age of 8 is mother passed away from abdominal cancer, so his father enrolled him in the very prestigious Edinburgh Academy.

10494489114_c59c9170c3_z.jpg

James was fascinated by geometry at a early age, many times learning something before he was instructed. At the age of 13 he won the schools mathematical medal and first prize in both English and poetry. At the age of 16 he starting attending classes at the University of Edinburgh, and in 1850 he enrolled at the University of Cambridge.

 

8784212715_a69700b03f_z.jpg

The largest impact he had on science were his discovery’s around the relationship between electricity, magnetism, and light. Even Albert Einstein credited him for laying the ground work for the Special Theory of Relativity. He said his work was “the most profound and the most fruitful that physics has experienced since the time of Newton.”

Maxwell also had a strong interest in color vision, he discovered how to take color photographs by experimenting with light filters.

But here at EXAIR we are very interested in his work on the theory that a “friendly little demon” could somehow separate gases into hot and cold flows, while unproven in his lifetime, did actually come to fruition by the development of the Vortex Tube.  Which does just that.

How A Vortex Tube Works

So here’s to you, James Clerk Maxwell…may we continue to recognize your brilliance, and be inspired by your drive to push forward in scientific developments.

Jordan Shouse
Application Engineer
Send me an email
Find us on the Web 
Like us on Facebook
Twitter: @EXAIR_JS

 

Photo credit to trailerfullofpix & dun_deagh