Discovery of The Vortex Tube

There are many theories regarding the dynamics of a vortex tube and how it works. Many students have studied them in hopes of advancing the physics or as part of their undergrad studies. The man that started it all was not intentionally researching it, however.

The Vortex Tube was invented by accident in 1928, by George Ranque, a French physics student. He was performing experiments on a vortex-type pump that he had developed and noticed that warm air exhausted from one end and cold air from the other. Ranque quickly changed his focus from the pump to start a company taking advantage of the commercial possibilities for this odd little device that produced both hot and cold air, using only compressed air, with no moving parts. The company was not successful, and the vortex tube was forgotten until 1945 when Rudolph Hilsch, a German physicist, published a widely read paper on the device.

A vortex tube uses compressed air as a power source, has no moving parts, and produces hot air from one end and cold air from the other. The volume and temperature of the two air streams is adjustable with a valve built into the hot air exhaust.  Temperatures as low as -50°F (-46°C) and as high as 260°F (127°C) are possible.

Compressed air is supplied to a vortex tube and passes through nozzles that are tangent to an internal counterbore. As the air passes through it is set into a spiraling vortex motion at up to 1,000,000 rpm. The spinning stream of air flows down the hot tube in the form of a spinning shell, like a tornado (in red). The control valve at the end allows some of the warmed air to escape and what does not escape reverses direction and heads back down the tube as a second vortex (in blue) inside of the low-pressure area of the larger warm air vortex. The inner vortex loses heat and exits through the other end of as cold air.

It is thought that both the hot and cold air streams rotate in the same direction at the same angular velocity, even though they are traveling in opposite directions. A particle of air in the inner stream completes one rotation in the same time of an air particle in the outer stream. The principle of conservation of angular momentum would say that the rotational speed of the inner vortex should increase because the angular momentum of a rotating particle (L) is equal to the radius of rotation (r) times it’s mass (m) times its velocity (v).  L = r•m•v.  When an air particle moves from the outer stream to the inner stream, both its radius (r) and velocity (v) decrease, resulting in a lower angular momentum. To maintain an energy balance for the system, the energy that is lost from the inner stream is taken in by the outer stream as heat. Therefore, the outer vortex becomes warm and the inner vortex is cooled.

At EXAIR, we have harnessed the cooling power of the vortex tube, and it can be found and utilized in such products as Spot CoolersCabinet Coolers, and Vortex Tubes themselves. If you have questions about Vortex Tubes, or would like to talk about any of the EXAIR Intelligent Compressed Air® Products, feel free to contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

EXAIR Cabinet Cooler Systems Stabilize Relative Humidity

EXAIR Cabinet Cooler Systems are able to cool your electrical panels using only clean, dry compressed air. Other systems such as cooling fans or heat exchangers use ambient air full of dust and humidity. The temperature of ambient air also fluctuates with the seasons and will be very warm in the summer months, which degrades their ability to cool as the temperature rises. One of the myths about compressed air cooling is that humidity from the compressed air source will enter the cabinet. A water/dirt filter separator will prevent condensate from entering the cabinet and since relative humidity is carried away with the hot air exhaust, relative humidity will stabilize to 45%. This video shows how quickly EXAIR’s Cabinet Cooler Systems will have an effect on relative humidity.

Dave Woerner
Application Engineer
@EXAIR_DW
DaveWoerner@EXAIR.com

Cabinet Coolers in January?

Dual CC outside

Without putting too much thought into it, one might assume that January would not be Cabinet Cooler season. But actually, our friends in the southern hemisphere (Australia, New Zealand, South Africa, Argentina, Chile and Brazil) are experiencing their summer at the very same time that we in the mid-west of the United States have been having some bone-chilling cold weather blow in from Canada. Our New Zealand distributor told me just the other day that they were having 35°C days with water restrictions and everyone is on fire watch because it is so hot and dry right now.

As uncomfortable as that might be for the folks living there, many must continue their production in the un-air conditioned environments. And in doing so, they have to keep their machines up and running to maintain production. But the controls for those machines are not always so cooperative because the CPU is overheating or the inspection camera is giving out because it is too hot.

Where do they turn?  EXAIR of course. Once our distributor partner assists the customer with sizing and makes recommendation (sometimes with a little help from us). The customer installs the Cabinet Cooler System and has taken care of their overheating problem within the application once and for all.

The reason why I say “once and for all”, is that the Cabinet Cooler Systems have no moving parts and are virtually maintenance-free. There are no filters to constantly change due to dirty factory environments. And best of all, the Cabinet Cooler can continue to operate in the range of 20 years plus.

When you compare the small cost of a Cabinet Cooler System to that of down time, lost production and the cost to repair burnt out controls, it is truly an easy decision to make.

So, back to our friends in the Southern Hemisphere, where hot and dry is the order of the day, consider having an EXAIR Cabinet Cooler for your application today. Contact us in the International Application Engineering / Sales Department or consult our International Distributor Locator to find the distributor near to you.

Neal Raker, International Sales Manager
nealraker@exair.com

Gardens & (Failed) Quick Fixes

With the stretch of hot weather we are having and the rain we got last week my garden at home is absolutely out of control.  At least it was until I spent a good two to three hours picking weeds and grass out of the garden. This year we doubled the size of our garden from last year.  When I did the garden last year I dug out most of the sod and it really helped cut down on the grass in the garden.  When we expanded this year though I was just a little too busy to get the sod dug out and when a good friend tilled the garden for me he churned all the grass into the area.   This was fine as he did it for free and I didn’t have to do it; but now I am paying for it.   The grass that was in that area is now growing faster than anything else in my garden and was actually choking out all of the onions I had planted.

First I tried to quick fix problem by throwing more dirt over top of the grass to smother it.  That worked for about a day.  So I did what I had to do, I got in on my hands and knees and picked every little bit of grass out, roots and all.   By the end of the next day the onions had all perked up, the tomatoes continued blooming and the zucchini look to be the first vegetable we will enjoy eating.

20140609_181943

The fact of the matter is that I didn’t take time to make sure everything was in order before expanding the garden.  I didn’t remove the sod, communicate that I preferred the sod out, or mention to my friend that if not removing the sod please chop it up well (a hard thing to state when your friend is doing you such a big favor).  Because of that I had to dedicated a good part of my day at home working on a problem I could have prevented.   The fact of the matter is a quick fix is just a temporary fix and it is only a matter of time before the real problem reappears and demands your attention.

cc fan

The same can be said when you band aid an electrical cabinet that is overheating by opening the door and putting a fan in it.   That doesn’t solve the problem, it may go away for a short moment, but then it will come back even worse. A fan will provide some temporary cooling but it will also deposit dirt and debris on to the electrical components (all that grime on the fan blades and guard is the same stuff being blown into your cabinet) which causes them to run hotter, short out, or burn.  So instead of using a quick fix give us a call and let us help you determine the correct Cabinet Cooler System to cool your cabinet and get the problem solved the right way. The reality of installing a Cabinet Cooler is it takes a short amount of time and effort to install. If compared to other cooling alternatives it may be considered a quick fix – but one that lasts years, is low maintenance, and reliable.

ccJUL_ACsensor186x149

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF