EXAIR Vortex Tubes: As Much Cold Air As You Need, As Cold As You Need It

If you’re looking for a reliable, consistent flow of cold air, there’s really no better way to produce it than with a Vortex Tube. There are no moving parts…the air flow and temperature from a particular model, set to a specific cold fraction, is only influenced by the compressed air supply pressure & temperature.

Pressure is easy to control…all you need is a suitable regulator.  Temperature CAN be a variable, depending on your type of compressor, if you have a dryer system (and what type it is,) and sometimes, ambient conditions…if, for example, a long pipe is run through a very hot environment like a foundry or a blast furnace operation.  In cases where supply pressure and/or temperature can be limitations, a higher capacity Vortex Tube, set to a lower Cold Fraction, may be specified.  Which brings me to the user inquiry that inspired today’s blog…

This particular customer uses our Model 3215 Vortex Tubes (15 SCFM, 1,000 Btu/hr) to provide cooling to analyzer systems that monitor certain quality parameters in their manufacturing processes.  The ability to precisely control the temperature in these systems makes for repeatable and accurate measurement of these parameters.   Their compressed air supply in this area is regulated to 80psig, they have a refrigerant-type dryer and climate-controlled facility, so their supply temperature is a consistent 70°F.  You couldn’t ask for better conditions for a successful Vortex Tube application, and they’ve worked great, for years.

Now, due to a plant expansion, they’re installing some of these analyzer systems in a location where the compressed air supply is limited to 60psig.  The required cooling capacity is going to be the same, so the Project Manager reached out to us to see if they could get the same amount of cooling with this new pressure limitation.  Here’s how they’re doing it:

We publish the rated performance of Vortex Tube products for a supply pressure of 100psig.  The Model 3215 Vortex Tube consumes 15 SCFM @100psig and, when set to an 80% Cold Fraction (meaning 80%…or 12 SCFM…of the 15 SCFM supply is directed to the cold end,) the cold air will be 54F colder than the compressed air supply temperature.  Here’s the performance table, so you can follow along:

EXAIR Vortex Tube Performance Table

Now, their supply is at 80psig.  Since air consumption is directly proportional to absolute supply pressure (gauge pressure PLUS atmospheric, which is 14.7psi at sea level,) we can calculate their units’ consumption as follows:

(80psig + 14.7psia) ÷ (100psig + 14.7psia) = 0.83 X 15 SCFM (@100psig) = 12.4 SCFM (@80psig)

So, with a 50°F temperature drop (from a supply @70°F,) they were getting 12.4 SCFM of cold air at 20°F.

As you can see from the table above, they’ll only get a 46°F drop at 60psig…and the flow won’t be as high, either.  So…we’ll need to get more air through the Vortex Tube, right?  Let’s use a little math to solve for what we need.

We still need 20°F cold air from 70°F compressed air, so, at 60psig, we’re looking at a Cold Fraction of ~70%.  And we still need 12.4 SCFM, so:

12.4 SCFM ÷ 0.7 = 17.7 SCFM @60psig (required supply)

Our Model 3230 Vortex Tube uses 30 SCFM @10opsig…at 60psig it’ll consume:

(60psig + 14.7psia) ÷ (100psig + 14.7psia) = 0.65 X 30 SCFM (@100psig) = 19.5 SCFM (@60psig)

That’s about 10% more flow than they needed, theoretically, which was close enough to start.  From there, they “dialed in” performance by regulating the supply pressure and Cold Fraction (see video, below):

If you’d like to find out more, or work through a cooling application, give me a call.

Russ Bowman
Application Engineer
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Vortex Tube Kits Make Heat Removal A (Cool) Breeze

I recently had the pleasure of discussing a cooling application with a customer.  The caller was familiar with our Cabinet Cooler Systems, and wanted to incorporate the same technology into a spot cooling application.  Problem was, he wasn’t sure about exactly how much cold air flow, and at what temperature, would suit his needs best…this was on a brand new mold (for plastic parts) that had just arrived.  His idea was to order a few different Vortex Tubes, and experiment with them.

I agreed that trying a few different Vortex Tube models would be a quick and easy way to find a solution, but I had a quicker and easier way: the Model 3930 Medium Vortex Tube Cooling Kit.  This gave him all the Generators that fit the Medium Vortex Tube, allowing him to make any medium Vortex Tube model he desired.  He would also be able to adjust the Cold Fraction to get the most effective temperature drop as well.

EXAIR Vortex Tube Cooling Kits come with all parts necessary to effect a wide range of cold air flow & temperatures.

With the Vortex Tube in place, it was very easy to configure the optimal cooling…as he decreased the Cold Fraction (to get colder air) he replaced the Generator (to get higher air flow.)  His application (cooling molded plastic parts) was satisfied with a Model 3225, set to a 70% Cold Fraction…this gave him 17.5 SCFM of cold air flow, at temperature of around 0F (a 71F drop from their compressed air supply temperature, which is around 70F.)

Is an EXAIR Cooling Kit right for your heat removal application?  If you’d like to find out,  give me a call.

Russ Bowman
Application Engineer
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Cooling Gelatin Pills Using The Mini Cooler

I recently worked with an OEM on a cooling application for a gelatin pill forming machine they designed for their customer. In their machine design, the gelatin film leaves an extruding machine then travels between 2 punch rollers to form the pills. After the pills are formed, they are supposed to drop onto a chute feeding a conveyor to carry the pills to the bottling/packaging area.

View of machine showing direction of travel for the film and punch rollers

The problem they were having was the film was retaining heat which caused the pills to occasionally stick to the roller, resulting in rejects and lost production time. They were looking for an economical way to blow cold air across the rollers and film but were concerned about putting too much demand on their customer’s compressed air system.

After reviewing the photos and discussing the details, I recommended they use our Model # 3308 Mini Cooler System with dual point hose kit. The Mini Cooler provides a 50°F temperature drop from the incoming supply air temperature and provides 550 Btu/hr. of cooling capacity. The system includes a swivel mag base for easy installation while the dual point hose kit would allow them to direct the cold air to blow across both rollers from a single device. Compressed air demand is minimal, at only 8 SCFM @ 100 PSIG, alleviating their concern for the customer’s compressed air system.

Model 3308 Mini Cooler System with 2-cold outlets – provides a focused stream of 20°F air (based on ambient supply of 70°F)

If you are having heat related issues with your process or to discuss a particular application or product, give me a call, I ‘d be happy to help.

Justin Nicholl
Application Engineer
justinnicholl@EXAIR.com
@EXAIR_JN

 

The Adjustable Spot Cooler Provides High Flexibility and Effectiveness

A customer emailed me with some questions about the using the EXAIR spot cooling technology for use on PEEK material being machined in a Swiss Turning machine. Typically, apart from drilling and parting, coolants are not necessary for thermoplastic machining operations.  In order to obtain the best surface finish and tightest tolerances, keeping the cutting area cool is required.  The ideal goal was to provide sub-zero air to the cutting area, while being quiet and easy to operate.  After reviewing the various EXAIR spot cooling products, it was determined that the Adjustable Spot Cooler System would satisfy all of the requirements.

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Model 3825 Adjustable Spot Cooler System

The Adjustable Spot Cooler System shown above is capable of producing temperatures from -30°F to room temperature, with just the turn of a knob.  Included in the package are (2) additional generators, which allow for more or less cold air flow rate, depending on the application cooling needs.  With the magnetic base, the system can be easily positioned, and the flexible hose allows for precise aim of the cold air flow. And, sound levels are kept below 75 dBA.

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Model 3825 Used in a Turning Operation

To recap, the Adjustable Spot Cooler System provides adjustable cold air temperature with the simple turn of a knob, includes additional generators to provide wide ranging flow rates, has a magnetic base to allow for positioning anywhere, on any machine, and has a flexible hose for directing the cold air wherever it is needed.

I would say that it is a Very Adjustable Spot Cooler.

To discuss spot cooling and your application, we ask you to contact EXAIR and one our  Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Quick, Cool, and Quiet – The EXAIR Adjustable Spot Cooler

I recently had the pleasure of assisting a caller with a cooling application. We’ve written before (more than once) about cooling applications & product selection, and I had a very similar conversation with this caller. Since the need was for cooling as quickly as possible to ambient temperature, the caller was keen on talking about Vortex Tubes.

This application entails operators placing small products, by hand, under the cold air flow for rapid cooling.  Now, a Vortex Tube can produce VERY low temperatures…down to -40F…so operator safety had to be addressed.  By keeping the Cold Fraction (the percentage of supply air flow which is directed to the cold end) high, we can also keep the temperature high enough to not present a hazard (i.e., frostbite) but still plenty low enough for effective cooling.

Since sound level was also a concern, we discussed mufflers…with Hot and Cold Mufflers installed on a Medium Vortex Tube (models 3215, 3225, or 3230, which were what we narrowed our discussion to,) a sound level of 81-84 dBA will be produced.  That’s within OSHA’s limits for 8-hour exposure, but isn’t exactly “communication-friendly” for operators that need to talk to each other on a regular basis.

The Model 3825 Adjustable Spot Cooler System incorporates the performance of the three Vortex Tube models that we were talking about into a convenient mag base mounted assembly, fitted with a cold muffler, flexible cold air hose, and additional sound level suppression to 72-74 dBA…which makes a significant difference in areas where operator conversation is critical.

EXAIR's Adjustable Spot Cooler provides cold air, on demand - quiet and easy!

EXAIR’s Adjustable Spot Cooler provides cold air, on demand – quiet and easy!

The temperature control knob allowed them to dial in the optimal cold air flow, keeping the temperature low enough, and flow high enough, for rapid cooling of the parts.

If you’d like to find out just how cool an EXAIR Vortex Tube/Spot Cooling Product can make your application, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Cabinet Coolers Keep Enclosures Free of Dirt and Dust…and Cool

One of the main focuses for Cabinet Cooler Systems is to cool electrical enclosures that are overheating due to inadequate cooling, failing air conditioners, or heat exchangers that are not performing due to high ambient conditions.  Another focus is the fact that the Cabinet Cooler Systems don’t require refrigerant based coolants, or fans that can move dirty ambient air into the cabinet. This is the portion I would like to focus on today.

If there are vents on the enclosure then these are sometimes covered with a filter media that is an easily forgotten maintenance item –  sometimes they are even removed.  This is an issue as it starts to allow the contaminants from the surrounding area to begin to enter the inside of an enclosure.  In case you have never seen a circuit board that is covered in oil mist and metal chips, it is terrifying to see a maintenance person that is trying to troubleshoot the machine for failures.  Not only does this present a fire hazard but it also presents the internals of the panel with a strong probability of failure.

Another item I have personally seen fail in the field are small fans mounted within enclosure vents to help circulate air through the enclosure.  This is a great idea if the ambient environment is climate controlled and has no dirt or debris in the air.   Even in a facility that is climate controlled there is still potential for airborne debris, dust, and contaminants to enter the cabinets. These are merely accelerated into the cabinet by the fan and distributed throughout the entire enclosure instead of just coming in and covering the area just inside of the vent.

The solution to all the problems above which can easily save thousands of dollars worth of damaged circuit boards or drives is an EXAIR Cabinet Cooler System.  The Cabinet Coolers will all provide a slight positive air flow within the enclosure and will help to keep those external ambient conditions out of the cabinet and away from valuable electronics.  Even with our thermostatically controlled systems (which turn on and off as needed to maintain internal temperature AND save air) we offer a Non-Hazardous Purge option which will permit a 1 SCFM flow of air through the Cabinet Cooler to always keep a slight positive pressure within the enclosure. When the cabinet needs to be cooled, it will open the solenoid valve and provide the full rate of cooling from the Cabinet Cooler System.  The Non-Hazardous Purge function is available for all three NEMA types of Cabinet Cooler Systems, 12, 4, and 4X.

NHP.PNG

If you would like to discuss the other benefits of utilizing EXAIR Cabinet Cooler Systems and which model is right for your enclosure, please contact us.

Brian Farno
Application Engineer Manager
BrianFarno@EXAIR.com
@EXAIR_BF

The Effect of Back Pressure on a Vortex Tube Part 2, Calculating Btu/Hr.

My previous blog post was about how Vortex Tubes react when there is back pressure due to a restriction on either the hot or cold discharge of the Vortex Tube.  In it I mentioned that there is a formula to calculate what the cooling capacity (Btu/Hr) will be if there is no way to avoid operating the Vortex Tube without back pressure on the discharge. That is the calculation focus of this blog – calculating Btu/hr of a Vortex Tube with back pressure.

To continue with the same example, the calculations from the previous blog are shown below.  Last time the example Vortex Tube was operating at 100 psig inlet pressure, 50% cold fraction, and 10 psi of back pressure. We will need some additional information to determine the Btu/Hr capacity. The additional information needed is the temperature of the supplied compressed air as well as the ambient air temperature desired to maintain.  For the example the inlet compressed air will be 70°F and desired ambient air temperature to maintain will be 90°F.

(100 psig + 14.7 psia) / (10 psig + 14.7 psia) = X / 14.7 psia
4.6437 = X / 14.7
X= 14.7 * 4.6437
X = 68.2628
(Values have been rounded for display purposes)

The calculation above gives the compensated operating pressure (X = 68.2628) which will be needed for the BTU/hr calculation. The rated air consumption value of the Vortex Tube will also need to be known.  A 30 SCFM rated generator will be used for this example, the normal BTU capacity of a Vortex Tube with a 30 SCFM generator is 2,000 BTU/hr.

First, determine the new consumption rate by establishing a ratio of the compensated pressure (68.2628 psi) against the rated pressure (100 psi) at absolute conditions (14.7 psia).

(68.2628 PSIG + 14.7 (atmospheric pressure)) / (100 PSIG (rated pressure) + 14.7) = .7233
.7233 x 30 SCFM  = 21.7 SCFM Input 

Second, the volumetric flow of cold air at the previously mentioned cold fraction (50%) will be calculated.  To do this multiply the cold fraction setting (50%) of the Vortex Tube by the compensated input consumption (21.7 SCFM) of the Vortex Tube.

50% cold fraction x 21.7 SCFM input = 10.85 SCFM of cold air flow

Third, the temperature of air that will be produced by the Vortex Tube will need to be calculated.  For this consult the Vortex Tube performance chart which is shown below. To simplify the example the compensated operating pressure (68.2628 psi) will be rounded to 70 psig and to obtain the 70 psig value the mean between 80 psig and 60 psig performance from the chart will be used.

Cold Fraction

EXAIR Vortex Tube Performance Chart

For the example: A 70 psig inlet pressure at 50% cold fraction will produce approximately an 88°F drop.
Fourth, subtract the temperature drop (88°F) from the temperature of the supplied compressed air temperature (70°F).

70°F Supply air – 88°F drop = -18°F Output Air Temperature

Fifth,  determine the difference between the temperature of the air being produced by the Vortex Tube (-18°F) and the ambient air temperature that is desired (90°F).

90°F ambient – -18°F air generated = 108°F difference.

The sixth and final step in the calculation is to apply the answers obtained above into a refrigeration formula to calculate BTU/hr.

1.0746 (BTU/hr. constant for air) x 10.85 SCFM of cold air flow x 108°F ΔT = 1,259 BTU/hr.

In summary, if a 2,000 BTU/hr. Vortex tube is operated at 100 psig inlet pressure, 50% cold fraction, 70°F inlet air to maintain a 90°F ambient condition with 10 psi of back pressure on the outlets of the Vortex Tube the cooling capacity will be de-rated to 1,259 BTU/hr.  That is a 37% reduction in performance.  If a back pressure cannot be avoided and the cooling capacity needed is known then it is possible to compensate and ensure the cooling capacity can still be achieved.  The ideal scenario for a Vortex Tube to remain at optimal performance is to operate with no back pressure on the cold or hot outlet.

Brian Farno
Application Engineer Manager
BrianFarno@EXAIR.com
@EXAIR_BF

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