Ultraviolet Curing and Vortex Tube Cooling

Recently EXAIR worked on a project to cool down parts that were using Ultraviolet (UV) light to cure a surface coating. Ultraviolet curing is a photochemical process that uses UV light to cure/dry certain inks, coatings, and adhesives. Due to the fact that UV light produces a good amount of heat the product would heat up during the curing process and create issues for them down the line which slowed down production in order let them cool. The simple solution to this was the use of the vortex tube to blow on the product to cool it down during the process. By doing so they were able cool the product down to a suitable temperature for the process to speed up.

EXAIR’s Small, Medium, and Large Vortex Tubes


EXAIR’s Vortex Tubes are great for cooling down surfaces to temperatures below ambient thanks to the cold air stream that is produced from the vortex tube. Vortex tubes use a source of compressed air to create both a hot and cold stream of air simultaneously which allows the unit to be used for cooling but also heating applications. The amount of air flow coming out of either end of the Vortex Tube can be controlled; by doing so one can adjust the temperature of the air streams coming out.

There are numerous methods to distribute the cold air flow from a lone, or a series of, Vortex Tubes.

Although the main application for the Vortex Tube is to be used for cooling, it is occasionally used to heat as well. Heating applications are uncommon, but they are still possible. Since a vortex tube creates a cold and hot stream of air; by controlling what the fraction of air is flowing out of the cold end you can create a temperature rise (a rise from the starting air temp) of up to 195F! Now that is hot.

If you have any questions about compressed air systems or want more information on any of EXAIR’s 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
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Vortex Tube Overview

VT_air2

A Vortex Tube uses an ordinary supply of compressed air as a power source, creating two streams of air, one hot and one cold – resulting in a low cost, reliable, maintenance free source of cold air for spot cooling solutions.

The EXAIR Vortex tubes are made of stainless steel, which provides resistance to wear, corrosion and oxidation – ensuring years of reliable, maintenance free operation

How_A_Vortex_Tube_Works

The cold air flow and temperature are easily controlled by adjusting the slotted valve in the hot air outlet.  Opening the valve reduces the cold air flow and the cold air temperature.  Closing the valve increases the cold air flow and and the cold air temperature.

EXAIR Vortex Tubes come in three sizes. Within each size, a number of flow rates, which are dictated by a small internal generator, are available. Selection of the appropriate Vortex Tube can be achieved either by knowing the BTU/hr (Kcal/hr) requirements or the desired flow and temperature requirements. Selection is then based on the specification table (BTU/hr or Kcal/hr is known) or the performance tables (flow and temperature is known.)

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Vortex Tube Specification Tables

 

Cold Fraction
Vortex Tube Performance Tables

The performance of a Vortex Tube is reduced with back pressure on the cold air exhaust. Low back pressures up to 2 PSIG ( 0.1 Bar) will not change performance and a 5 PSIG (0.3 Bar) will change the temperature drop by approximately 5°F (2.8°C)

The use of clean air is essential, and filtration of 25 microns or less is recommended.  EXAIR offers filters with 5 micron elements and properly sized for flow.

A Vortex Tube provides a temperature drop to the incoming supply air.  High inlet temperatures will result in a corresponding rise in the cold air temperature.

EXAIR offers mufflers for both the hot and cold air discharge.  If the cold air is ducted, muffling may not be required.

For best performance, operation at 80 to 110 PSIG (5.5 to 7.6 Bar) of supply pressure is recommended. The Vortex Tubes have a maximum pressure rating of 250 PSIG (17.2 Bar) and a minimum requirement of 20 PSIG (1.4 Bar)

To discuss your application and how a Vortex Tube or any EXAIR Intelligent Compressed Air Product can improve your process, feel free to contact EXAIR, myself, or one of our other Application Engineers. We can help you determine the best solution!

Brian Bergmann
Application Engineer

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A Solution for This and a Solution for That – Solving Problems Throughout the Plant

EXAIR’s 15 extensive product lines solve problems in production processes everyday. From cooling to laser lens protection (as you will see below) to static elimination, general shop housecleaning, conveying and air conservation –  we would like to help solve your problems.

Last week, I got an email from a customer.  It was late in the day, and I was spent from a busy day.  The customer was emailing for (2) reasons. First, they wanted to express their appreciation for our efforts several months ago regarding an application for a Vortex Tube. Over the course of a couple of weeks, we shared information and ideas back and forth regarding the Vortex Tube technology, how it works, and the various considerations when choosing the appropriate model.  They ended up purchasing a unit and put it into operation.  The application involved a plastic tubing cutting process and in this instance both the cold and hot air streams could be utilized to improve the process. The process involves heating up the material so it would lose its memory set, and then a cooling operation to improve the material cutting and handling.  Below is an excerpt from the recent email:

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How_A_Vortex_Tube_Works
The Vortex Tube takes in compressed air, and creates a Cold Stream and a Hot Air Stream

The second reason for the email was that he needed help with another application and based on the success of the initial collaboration, he knew he could trust in EXAIR to help find a solution that would work.  The new application involves protecting a camera lens from debris created during a wire cutting laser process. The lens is getting hit with spatter and damage is starting to occur. Our collaboration has begun, and we are looking at the Super Air Knife and Flat Super Air Nozzle as possible solutions, each of them providing a strong air flow to direct the debris away from the lens.

To discuss your application and how an EXAIR Intelligent Compressed Air Products can help your process, feel free to contact EXAIR and one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Vortex Tubes Make Hot Air Too

Back in the spring, my good friend and co-worker Neal Raker wrote a great piece, titled “Can I Use A Vortex Tube For Heating?” which I will try my best not to borrow too much from or outright plagiarize in the blog to follow. I only mention it because I had the pleasure of helping a customer with one of the “usually few and far between” Vortex Tube heating applications recently.

Like Neal said, the conditions under which Vortex Tubes fit a heating application are fairly narrow, but certainly not unheard of. In this situation, a reciprocating air motor had been in place on a piece of factory machinery for years. A recent change in the part being manufactured meant that the motor had to be slowed down, which meant throttling down on the vent valve on the motor’s pneumatic exhaust. When they did this, the valve became prone to freezing up, meaning someone had to rig up a heat gun and climb up on top of the machine to the vent valve, directing hot air on the valve until it thawed. It got to be a real hindrance to the process when this happened several times a day.

The caller was familiar with our Vortex Tube products, having used Mini Coolers and Cold Guns in other parts of the plant. He knew that there was hot air coming out of the other end, and thought it could be used to thaw the vent valve, but was concerned, because it was such a low flow.

Mini Cooler (left) and Cold Gun (right).
Mini Cooler (left) and Cold Gun (right).  Cold air from one end; hot exhaust minimized on the other.

He was right: the hot air exhaust of both the Mini Cooler and Cold Gun is a small fraction of the total air supply…that’s by design. Also, it’s passed through a noise reducing muffler which further spreads it out to make it nice & quiet…also by design.

That’s when a fuller explanation of Vortex Tube operation came into play: See, the Mini Coolers and Cold Guns are all set to a high Cold Fraction (the percentage of supply air that is directed to the cold end,) so, although the hot exhaust is indeed fairly hot, there’s just not a lot of it. By contrast, our 3400 Series Maximum Cold Temperature Vortex Tubes are adjustable for lower Cold Fractions (from 20-50%,) meaning that the hot exhaust flow can range from 50-80% of the supply air flow. Additionally, the hot end of the Vortex Tube has male NPT threads, for convenient porting & direction of the hot air flow.

The EXAIR Vortex Tube.  Cold air from one end; hot air from the other.  Fully adjustable.
The EXAIR Vortex Tube. Cold air from one end; hot air from the other. Fully adjustable.

Now, back to the conditions that made this a good fit for the Vortex Tube: the machinery already had an ample and easily accessible supply of compressed air…they were able to tap a line from the air motor’s supply. The closest outlet for their heat gun was on the other side of the walkway, which meant they had to stretch an extension cord across the walkway, creating a trip hazard. The vent valve is also small enough that they could use a Model 3402 Vortex Tube, which utilizes only 2 SCFM @100psig…a tiny fraction of what the air motor uses.

With the Vortex Tube mounted permanently in place, the vent valve now operates flawlessly, without the need for manually thawing with the incredibly inconvenient heat gun.

If you think you might have a decent fit for a Vortex Tube heating application, give us a call. You may be right.

Russ Bowman
Application Engineer
(513)671-3322 local
(800)923-9247 toll free
(513)671-3363 fax
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