A manufacturer of automotive power transmission shafts was experiencing frequent failure of high pressure plastic rollers on their spin tester. There are four rollers in a 90° array that center the shaft during spin testing. They exert a pressure of around 1,500psi onto the shaft while it’s rotating at 1,000rpm. This generates enough heat to actually melt the rubber coating on rollers, which means stopping testing (which holds up production) while they change out the rollers. Just for it to start all over again.
Thing was, they wanted to mount the Adjustable Spot Coolers where they could have access to the Temperature Control Valve, but the cold air Hose Kit wouldn’t reach the shaft. So they got a couple of extra sections of the cold air hose…they needed one section of the ‘main’ (shown circled in blue, below) to reach into the test rig’s shroud, and two sections of the ‘branch’ (circled in green) to reach to each roller.
Now, adding too much hose length will start to put line loss on the cold air flow, and it will pick up heat from the environment. But if you just need that extra foot of hose to get the job done, this generally works just fine. The extra foot or so they’ve added (5″ to the main and 6″ to each branch) has solved their problem…they haven’t had to replace a roller since the Adjustable Spot Cooler Systems were installed.
The EXAIR Vortex Tubes use compressed air to generate cold air down to -50 deg. F (-46 deg. C) without any moving parts, freon, or electricity. By design, it will produce hot air at one end and cold air at the other. EXAIR offers different cooling capacities ranging from 135 BTU/hr (34 Kcal/hr) to 10,200 BTU/hr (2,570 Kcal/hr). This cooling phenomenon begins by spinning the air at a high rate of speed inside the Vortex Tube. The “separation” of temperatures starts at the generator. In this blog, I will discuss the features of the generator and how our design allows for an efficient way to cool and heat the air flows.
EXAIR stocks three different sizes of the Vortex Tubes; small, medium, and large. Each Vortex Tube will use a generator to define the cooling capacity and compressed air usage. When compressed air enters the Vortex Tube, it will have to pass through the generator first. The generators are engineered with vane openings to initiate the spinning of the air and to control the amount of air that can pass through it. As an example, for a medium-sized Vortex Tube, a model 10-R generator will only allow 10 SCFM (283 SLPM) of air at 100 PSIG (6.9 Bar). While in that same size body, a model 40-R generator will allow 40 SCFM (1,133 SLPM) of air at 100 PSIG (6.9 Bar) to be used. Precision in the design of the generators is what sets EXAIR apart with efficiency and effectiveness in cooling.
EXAIR created a chart to show the temperature drop for the cold end and temperature rise for the hot end, relative to the incoming compressed air temperature. Across the top of the chart, we have Cold Fraction and along the side, we have the inlet air pressure. The Cold Fraction is the percentage of the inlet air that will blow out the cold end of the Vortex Tube. This is adjustable with a Hot Exhaust Air Valve at the hot end.
As you can see from the chart, the temperature difference changes as the Cold Fraction and inlet air pressure changes. You may notice that it is independent of the size of the generator. So, no matter which size Vortex Tube or generator is used, the temperature drop and rise will follow the chart above. But just remember, cooling capacity is different than cooling temperature. At the same settings, a larger generator will give you more mass of air to cool faster.
Now, let’s look inside the Vortex Tube (reference photo above). As the compressed air passes through the generator, the change in pressure will create a powerful vortex. This spinning vortex will travel toward one end of the tube where there is an air control valve, or Hot Air Exhaust Valve. This valve can be adjusted to increase or decrease the amount of hot air that leaves the Vortex Tube. The remaining part of the air is redirected toward the opposite end as the cold flow, or Cold Fraction.
Now, what separates EXAIR Vortex Tubes from our competitors are the three different styles of generators and two different materials for each size. These generators are engineered to optimize the compressed air usage across the entire Cold Fraction chart above. With temperatures above 125 oF (52 oC), EXAIR offers a brass generator for the Vortex Tubes. The same precision design is applied but for higher ambient temperatures. With the wide range of Vortex Tubes and generators, we can tackle many types of cooling applications.
If you would like to discuss your cooling requirement with an Application Engineer at EXAIR, we will be happy to help. This unique phenomenon to generate cold air with no moving, freon, or electricity could be a great product to use in your application.
Throughout my tenure with EXAIR there are may days where I have tested different operating pressure, volumetric flow rates, back pressures, lengths of discharge tubing, generator compression, and even some new inquiries with cold air distribution all on a vortex tube. These all spawn from great conversations with existing customers or potential customers on different ways to apply and applications for vortex tubes.
Many of the conversations start in the same spot… How exactly does this vortex tube work, and how do I get the most out of it? Well, the answer is never the same as every application has some variation. I like to start with a good idea of the area, temperatures, and features of exactly what we are trying to cool down. The next step is learning how fast this needs to be done. That all helps determine whether we are going to be looking at a small, medium, or large vortex tube and which cooling capacity to choose. After determining these factors the explanation on how to adjust the vortex tube to meet the needs of the application begins.
This video below is a great example of how a vortex tube is adjusted and what the effects of the cold fraction have and just how easy it is to adjust. This adjustment combined with varying the air pressure gives great versatility within a single vortex tube.
The table below showcases the test points that we have cataloged for performance values. As the video illustrates, by adjusting the cold fraction lower, meaning less volumetric flow of air is coming out of the cold side and more is exhausting out the hot side, the colder the temperature gets.
This chart helps to determine the best case scenario of performance for the vortex tube. Then the discussion leads to delivery of the cold or hot air onto the target. That is where the material covered in these two blogs, Blog 1, Blog 2 comes into play and we get to start using some math. (Yes I realize the blogs are from 2016, the good news is the math hasn’t changed and Thermodynamics hasn’t either.) This then leads to a final decision on which model of vortex tube will best suit the application or maybe if a different products such as a Super Air Amplifier (See Tyler Daniel’s Air Amplifier Cooling Video here.)is all that is needed.
Where this all boils down to is, if you have any questions on how to apply a vortex tube or other spot cooling product, please contact us. When we get to discuss applications that get extremely detailed it makes us appreciate all the testing and experience we have gained over the years. Also, it helps to build on those experiences because no two applications are exactly the same.
One of our more versatile cooling devices is the Adjustable Spot Cooler. The temperature can be changed from ambient down to -30 deg. F (-34 deg. C) with a turn of a knob. In addition to this, the cooling capacity can be modified as well by simply changing the generator. In this video, I will show you how to do this.
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.
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.
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.
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.
The EXAIR Mini Cooler family is one of the many vortex tube based Spot Cooler products that EXAIR offers. This is the smallest of the group coming in at 550 BTU/hr of cooling capacity. The Mini Cooler Systems are available in two options.
The Single Point Outlet option will give you ten inches of flexible cold outlet to easily position the cold air stream near the target point.
The Dual Point Outlet option gives ten inches of 1/4″ flexible outlet that then splits to two separate four inch lengths of 1/4″ flexible cold outlet hoses.
Both include point or flat fan tips for the cold air outlets
Both include a manual drain filter separator
both include the swivel magnetic base with 100 lb. pull magnet.
The single point hose kit is ideal for small diameter milling or drilling applications where the cold air can cover the contact area of the cutter. It can also be used on soldering, industrial sewing, ultrasonic welding, or even small punching applications to list just a few.
The dual point hose kit is ideal for two separate small diameter cutters, one larger diameter cutter, rotary style knives where there material is being slit, or larger diameter multi-point ultrasonic welders/punches.
When using the Mini Cooler the adjustable cold outlet stays in place and can easily bend around fixtures, spindles, welding horns, or dye aligning pins. The swivel magnetic base gives additional adjustment at the base of the cooler to aid in the versatility of this product. To further the adjustability of the cooler the operating pressure can easily be adjusted to lower or raise the cooling capacity of the Mini Cooler to meet the demands of the precise application.
If you believe you have an application that would benefit from the use of a Mini Cooler, or you are unsure which product would be ideal for your application please contact an Application Engineer. we are all here, willing to help however possible to get your application improved in both safety and efficiency.
By using only a source of compressed air, theCold Gun and High Power Cold Gun produces a stream of clean, cold air 50°F (28°C) below your compressed air supply temperature. The Cold Gun is very quiet at only 70 dBA and has no moving parts to wear out. Just supply it with clean compressed air and it’s maintenance free.
How does it work, and what are the benefits?
The Cold Gun uses compressed air to produce a stream of clean, cold air at 50°F (28°C) below supply air temperature. Generally this will be 20°F-30°F outlet temperature.
They use Vortex Tubetechnology…no moving parts to wear out.
Instant cold air flow with no moving parts!
Cold flow and temperature are preset to optimize cooling capability, and are non-adjustable to prevent freeze-up during use.
Eliminates the expense of both the purchase & disposal of cutting fluids when replacing expensive mist systems.
Removes the potential for health problems associated with breathing mist & vapors, and the safety issue of slipping on a wet floor.
Cold Gun Aircoolant System selection is easy & straightforward…we offer a standard, and a High Powerversion to meet your specific needs.
We also offer Single & Dual Point Hose Kits, to further meet the needs of your application.
One of the best applications I have seen with our cold gun came from a customer in Peru. They are a gold mining operation and they were having trouble with the liquid they were using to cool a saw. Read all about it here!
If you have an application that you believe would be better served by the use of an EXAIR Cold Gun, give us a call.