Do you need a proven way to reduce downtime and increase productivity on a variety of operations involving small parts where heat is a problem? EXAIR‘s Mini Cooler produces a stream of 20°F (-7°C) cold air to prevent heat build up and blow away chips and debris.
Especially effective on high speed operations, the Mini Cooler helps to prevent burning, melting, and heat related breakage, and while doing so, at a quiet 76 dBA sound level. Better yet, all done with no moving parts to wear out.
Mini Cooler Cooling a Small Mill Operation
Some popular applications for the Mini Cooler are – small tool cooling, needle cooling, blade cooling, and lens grinding.
There are several advantages to take note of – low cost, increased production rates, better tolerances, and quiet and compact.
The Mini Cooler Systems are available with One or Two Cold Outlets, and also include a 1″ wide Flare Nozzle Tip, and a Manual Drain Air Filter to clean the air, ensuring long, trouble free operation.
Using just 8 SCFM of 100 PSIG compressed air, the Mini Cooler will not tax your compressed air system. Its small size allows it to fit in areas where larger systems could not fit. The powerful magnetic base sticks to any ferrous surface and and provides up to 100 pounds of pull force.
If you have any questions about the Mini Cooler, the Adjustable Spot Cooler, Cold Gun or any EXAIR compressed air product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.
I had the pleasure of discussing a spot cooling application with a customer this morning. He wanted to get more flow from his Adjustable Spot Cooler, but still keep the temperature very low. He machines small plastic parts, and he’s got enough cold flow to properly cool the tooling (preventing melting of the plastic & shape deformation) but he wasn’t getting every last little chip or piece of debris off the part or the tool.
After determining that he had sufficient compressed air capacity, we found that he was using the 15 SCFM Generator. The Adjustable Spot Cooler comes with three Generators…any of the three will produce cold air at a specific temperature drop; this is determined only by the supply pressure (the higher your pressure, the colder your air) and the Cold Fraction (the percentage of the air supply that’s directed to the cold end…the lower the Cold Fraction, the colder the air.)
Anyway, the 15 SCFM Generator is the lowest capacity of the three, producing 1,000 Btu/hr of cooling. The other two are rated for 25 and 30 SCFM (1,700 and 2,000 Btu/hr, respectively.)
He decided to try and replace the 15 SCFM Generator with the 30 SCFM one…his thought was “go big or go home” – and found that he could get twice the flow, with the same temperature drop, as long as he maintained 100psig compressed air pressure at the inlet port. This was more than enough to blow the part & tool clean, while keeping the cutting tool cool, and preventing the plastic part from melting.
Model 3925 Adjustable Spot Cooler System comes with a Dual Outlet Hose Kit, and three Generators for a wide range of cooling performance.
If you’d like to find out how to get the most from a Vortex Tube Spot Cooling Product, give me a call.
Russ Bowman
Application Engineer
Find us on the Web
Follow me on Twitter
Like us on Facebook
A vortex tube is an interesting device that has been looked upon with great fascination over the last 89 years since its discovery by George Ranque in 1928. What I’d like to do in this article is to give some insight into some of the physics of what is happening on the inside.
With a Vortex Tube, we apply a high pressure, compressed air stream to a plenum chamber that contains a turbine-looking part that we call a generator to regulate flow and spin the air to create two separate streams. One hot and one cold.
The generator is a critical feature within a vortex tube that not only regulates flow and creates the vortex spinning action, it also aligns the inner vortex to allow its escape from the hot end of the vortex tube. Note the center hole on the photo below. This is where the cooled “inner vortex” passes through the generator to escape on the cold air outlet.
Vortex generator
Once the compressed air has processed through the generator, we have two spinning streams, the outer vortex and the inner vortex as mentioned above. As the spinning air reaches the end of the hot tube a portion of the air escapes past the control valve; and the remaining air is forced back through the center of the outer vortex. This is what we call a “forced” vortex.
If we look at the inner vortex, this is where it gets interesting. As the air turns back into the center, two things occur. The two vortices are spinning at the same angular velocity and in the same rotational direction. So, they are locked together. But we have energy change as the air processes from the outer vortex to the inner vortex.
If we look at a particle that is spinning in the outer vortex and another particle spinning in the inner vortex, they will be rotating at the same speed. But, because we lost some mass of air through the control valve on the hot end exhaust and the radius is decreased, the inner vortex loses angular momentum.
Angular momentum is expressed in Equation 1 as:
L = I * ω
L – angular momentum
I – inertia
ω – angular velocity
Where the inertia is calculated by Equation 2:
I = m * r2
m – mass
r – radius
So, if we estimate the inner vortex to have a radius that is 1/3 the size of the outer vortex, the calculated change in inertia will be 1/9 of its original value. With less mass and a smaller radius, the Inertia is much smaller. The energy that is lost for this change in momentum is given off as heat to the outside vortex.
Adjustments in output temperatures for a Vortex Tube are made by changing the cold fraction and the input pressure. The cold fraction is a term that we use to show the percentage of air that will come out the cold end. The remaining amount will be exhausted through the hot end. You can call this the “hot fraction”, but since it is usually the smaller of the two flows and is rarely used, we tend to focus on the cold end flow with the “cold fraction”. The “Cold Fraction” is determined by the control valve on the hot end of the Vortex Tube. The “Cold Fraction” chart below can be used to predict the difference in temperature drop in the cold air flow as well as the temperature rise in the hot air flow.
Vortex Tube Cold Fraction
By combining the temperature drops expressed above with the various flow rates in which Vortex Tubes are available, we can vary the amount of cooling power produced for an application. The above cold fraction chart was developed through much testing of the above described theory of operation. The cold fraction chart is a very useful tool that allows us to perform calculations to predict vortex tube performance under various conditions of input pressure and cold fraction settings.
The most interesting and useful part about vortex tube theory is that we have been able to harness this physical energy exchange inside a tube that can fit in the palm of your hand and which has a multitude of industrial uses from spot cooling sewing needles to freezing large pipes in marine applications to enable maintenance operations on valves to be performed.
We would love to entertain any questions you might have about vortex tubes, their uses and how EXAIR can help you.
EXAIR is based in Cincinnati, OH and it is where we design and manufacture our products. Since we are the manufacturer, we can design and build custom product when your application demands particular features. Vortex Tubes are the foundation of our cooling products and can be customized to suit your needs in many ways…
Vortex Family
The EXAIR Vortex Tube uses compressed air to generate a cold air stream at one end and a hot air stream at the other end. This phenomenon in physics is also known as the Ranque-Hilsch tube. It can generate very cold or very hot air without any moving parts, motors, or Freon. Thus; making it low cost, reliable, and maintenance free. The EXAIR Vortex Tube can generate
Air temperatures from -50 to +260 deg. F (-46 to +127 deg. C).
Flow rates from 1 to 150 SCFM (28 to 4,248 SLPM)
Refrigeration up to 10,200 BTU/hr (2,570 Kcal/hr)
Cooling or Heating with the Vortex Tube
With a wide range of cooling and heating applications, the EXAIR Vortex Tubes can be an ideal product for you. They are used for cooling electronics, CCTV cameras, and soldered parts. They are also useful for setting hot melts, gas sampling, and environmental chambers. With its very compact and versatile design, it can be mounted in tight places to apply heated or cold air to your process. The Vortex Tubes are used for improving process times in cooling, protecting equipment, or setting specific temperature requirements. If you need a Vortex Tube to be more specific to your application, EXAIR can manufacture a proprietary product in the following ways:
Preset Vortex Tubes – the standard Vortex Tube has a screw on the hot end to adjust the cold and hot air temperatures. To make the Vortex Tube tamper-resistant, EXAIR can replace the screw with a preset hot valve. If you can supply the temperature and flow requirements for your application, EXAIR can determine the correct diameter hole to give you a consistent temperature and flow from the Vortex Tube.
Materials – The standard Vortex Tubes has a maximum temperature rating of 125 deg. F (52 deg. C). For elevated ambient temperature, we offer a brass generator which will increase the temperature rating to 200 deg. F (93 deg. C). If other materials are needed for food, pharmaceutical, or chemical exposure, we can also offer stainless steel for the hot plug, cold cap, and generator. I have seen Vortex Tubes made entirely from 316SS and even one made with a brass body. There are EXAIR Vortex Tubes with special material o-rings and hot valves or with customized muffler assemblies.
Fittings – Our standard units have threaded connections on the Vortex Tube to connect fittings and tubing. In certain applications to improve mounting and assembly, special fittings may be required for ease of installation. EXAIR can attach or modify these parts to the Vortex Tube to meet your requirements.
At EXAIR, we pride ourselves with excellent customer service and quality products. To take this one step further, we offer specials to accommodate your applications. As a manufacturer of the Vortex Tubes, we can work with our customers to generate a custom product with high quality, fast delivery, and a competitive price. So, if you do need a special Vortex Tube to give you a specific temperature, ease of mounting, or a proprietary product for your OEM design, you can discuss your requirements with an Application Engineer. We will be happy to help you.
