The Adjustable Spot Cooler – Cold Air to -30°F (-34°C) From Your Compressed Air Supply

The Adjustable Spot Cooler is a low cost, reliable , maintenance free way to provide spot cooling to a myriad of industrial applications. Simply turn the knob, and the temperature can be changed to suit the needs of the process. The Adjustable Spot Cooler delivers precise temperature settings from -30°F (-34°C) to room temperature.

Adjustable Spot Cooler
Adjustable Spot Cooler

The Adjustable Spot Cooler utilizes the Vortex Tube technology that converts compressed air into a cold air stream. To learn more about EXAIR vortex tubes, click here.

  • It can produce temperatures form -30°F to +70°F (-34°C tp +21°C)
  • Parts included for flow rates of 15, 25 and 30 SCFM (425, 708, 850 SLPM.) The unit comes from the factory set at 25 SCFM (708 SLPM)
  • It can produce refrigeration up to 2,000 BTU/hr (504 Kcal/hr.)

A swivel magnetic base allows for easy mounting and portability, you can move it from machine to machine as needed. The flexible cold air outlet tubing holds its position and is easy to aim. Most importantly, there are no moving parts or CFC’s, ensuring maintenance free operation.

asc_onlathecmyk
The Adjustable Spot Cooler maintains critical tolerances on machined plastic parts

How the Adjustable Spot Cooler WorksThe Adjustable Spot Cooler incorporates a vortex tube to convert a supply of compressed air (1) into two low pressure streams, one hot and one cold. With the turn of a knob, the temperature control valve (2) allows some hot air to flow through a muffling sleeve and out the hot air exhaust (3). The opposite end provides a cold air stream (4) that is muffled and discharged through the flexible hose, which directs it to the point of use. The swivel magnetic base (5) provides easy mounting and portability.


The Adjustable Spot Cooler can produce a wide range of air flows and temperatures as determined by the temperature control valve knob setting and the generator installed. The generator controls the total SCFM (SLPM) of compressed air consumption, and is easy to change. From the factory, the 25 SCFM (708 SLPM) generator is installed, producing up to 1,700 BTU/hr (429 Kcal/hr) of cooling. For less cooling, the 15 SCFM (425 SLPM) generator can be installed, providing up to 1,000 BTU/hr (252 Kcal/hr) of cooling. And for more cooling, the 30 SCFM (850 SLPM) generator can be installed, providing up to 2,000 BTU/hr (504 Kcal/hr) of cooling.

Adjustable Spot Cooler Specifications

Two (2) Systems are available as shown below, and include the 15 and 30 SCFM (425 and 850 SLPM) generators, a filter separator, and either a single or dual point hose kit.

Adjustable Spot Cooler Systems3825_3925 adj spot cooler

If you have questions about the Adjustable Spot Cooler or any of the 16 different EXAIR Intelligent Compressed Air® Product lines, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer
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The Theory of the Vortex Tube

There are many theories regarding the dynamics of a vortex tube and how it works. Many a graduate student has studied them as part of their research requirements.

VT_air2

The Vortex Tube was invented by accident in 1928, by George Ranque, a French physics student. He was performing experiments on 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 stopped work on the pump, and started a company to take 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.

Here is one widely accepted explanation of the physics and the phenomenon of the vortex tube.VT

Compressed air is supplied to vortex tube and passes through nozzles that are tangent to to an internal counterbore (1). As the air passes through it is set into a spiraling vortex motion (2) 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 (4) at the end allows some of the warmed air to escape (6) 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 the through the other end of as cold air (5).

It is thought that that both the hot and cold air streams rotate in the same direction at the same angular velocity, even though they are travelling in opposite directions. A particle of air in the inner stream completes one rotation in the same amount of time that an air particle in the outer stream. The principle of conservation of angular momentum would say that the rotational speed of the inner inner vortex should increase because the angular momentum of a rotating particle (L) is equal to the radius of rotation (r) times its 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 Coolers, Cabinet Coolers, and the Vortex Tube themselves.

Harnessing the cooling power of the vortex tube 

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 EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer
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Vortex Tube Cooling Capacities and Generators

vortex_generator
Vortex  Medium Generator

Vortex Tube Generators are the internal component that controls the volume of air entering the Vortex Tube and ultimately the volume of cool/cold air produced.

Vortex family
Vortex Family

EXAIR manufactures three sizes of Vortex Tubes, small, medium & large.  Each size can produce a range of cooling power that can be changed by installing a different generator that will change the volume output capability of that Vortex Tube. The generators for small size vortex tubes can operate at 2, 4 or 8 SCFM (maximum cooling power of 550 BTU/HR),  generators for the medium size at 10, 15, 25, 30, or 40 SCFM (maximum cooling power of 2,800 BTU/HR) and the generators for the large size operate at 50, 75, 100 or 150 SCFM (maximum cooling power of 10,200 BTU/HR).  The Vortex Tube is sold with one generator installed.

The generators are marked with a number and a letter.  The number indicates the capacity (SCFM of air consumption) and the letter indicates the type of operation (“R” for maximum refrigeration or “C” for maximum cold temperature).  The maximum refrigeration (“R”) works best when the majority of the inlet air is exhausted out the cold end of the Vortex Tube. They work most efficiently with smaller temperature drops and larger volume of flow than the other generators. The maximum cold generators (“C”) can produce temperatures below 0°F, and work best when the minority of the inlet air is exhausted out the cold end of the Vortex Tube. The volume of cold air produced is less but you will experience greater temperature drops.

How A Vortex Tube Works

If a different cooling capacity is desired, other generators are available by either purchasing them individually or by purchasing one of the (3) highly versatile Vortex Tube Cooling Kits designated as the 3908 (small), 3930 (medium) or 3998 (large).  The Kits include the Vortex Tube, Filter Separator, Vinyl Tubing, Tubing Adapter, Tube Clamps, Cold End Muffler (Optional Hot End Muffler Available) and Both “R” & “C” Generators.

Vortex kit
EXAIR Medium Vortex Kit Includes: Vortex Tube, Filter Separator, Vinyl Tubing, Tubing Adapter, Tube Clamps, Cold End Muffler (Optional Hot End Muffler Available, Sold Separately) and Both “R” & “C” Generators (10, 15, 25, 30, or 40 SCFM).

If you would like to discuss Vortex Tubes, their Generators, or any of EXAIR’s safe, quiet & efficient compressed air products, I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer
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Vortex Tubes: What is a Cold Fraction & How to use it to Your Benefit

Vortex Tubes

EXAIR has wrote many different articles about how Vortex Tubes work and the applications in which they are used.  The idea of making cold air without any freon or moving parts is a phenomenon.  This phenomenon can generate cold air to a temperature as low as -50 oF (-46 oC).  In this article, I will explain the adjustment of the Vortex Tube to get different temperatures and cooling effects in reference to the Cold Fraction.

To give a basic background on the EXAIR Vortex Tubes, we manufacture three different sizes; small, medium, and large.  These sizes can produce a range of cooling capacities from 135 BTU/hr to 10,200 BTU/hr.  The unique design utilizes a generator inside each Vortex Tube.  The generator controls the amount of compressed air that can enter into the Vortex Tube.  As an example, a medium-sized Vortex Tube, model 3240, will only allow 40 SCFM (1,133 SLPM) of compressed air to travel into the Vortex Tube at 100 PSIG (6.9 bar).  While a small-sized Vortex Tube, model 3208, will only allow 8 SCFM (227 SLPM) of compressed air at 100 PSIG (6.9 bar).  EXAIR manufactures the most comprehensive range from 2 SCFM (57 SLPM) to 150 SCFM (4,248 SLPM).

Vortex Tube Exploded View

After the compressed air goes through the generator, the pressure will drop to slightly above atmospheric pressure.  (This is the “engine” of how the Vortex Tube works).  The air 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 air that leaves the hot end.  The remaining portion of the air is redirected toward the opposite end of the Vortex Tube, called the cold end.  By conservation of mass, the hot and cold air flows will have to equal the inlet flow as shown in Equation 1:

Equation 1: Q = Qc + Qh

Q – Vortex Inlet Flow (SCFM/SLPM)

Qc – Cold Air Flow (SCFM/SLPM)

Qh – Hot Air Flow (SCFM/SLPM)

Cold Fraction is the percentage of air that flows out the cold end of a Vortex Tube.  As an example, if the control valve of the Vortex Tube is adjusted to allow only 20% of the air flow to escape from the hot end, then 80% of the air flow has to be redirected toward the cold end.  EXAIR uses this ratio as the Cold Fraction; reference Equation 2:

Equation 2: CF = Qc/Q * 100

CF = Cold Fraction (%)

Qc – Cold Air Flow (SCFM/SLPM)

Q – Vortex Flow (SCFM/SLPM)

Vortex Tube Charts

EXAIR created a chart to show the temperature drop and rise, relative to the incoming compressed air temperature.  Across the top of the chart, we have the Cold Fraction and along the side, we have the inlet air pressure.  As you can see, the temperature changes as the Cold Fraction and inlet air pressure changes.  As the percentage of the Cold Fraction becomes smaller, the cold air flow becomes colder, but also the air flow becomes less.  You may notice that this chart is independent of the Vortex Tube size.  So, no matter the generator size of the Vortex Tube that is used, the temperature drop and rise will follow the chart above.

Vortex Tube Example

How do you use this chart?  As an example, a model 3240 Vortex Tube is selected.  It will use 40 SCFM of compressed air at 100 PSIG.  We can determine the temperature and amount of air that will flow from the cold end and the hot end.  The inlet pressure is selected at 100 PSIG, and the Hot Exhaust Valve is adjusted to allow for a 60% Cold Fraction.  Let’s use an inlet compressed air temperature to be 68 oF.  With Equation 2, we can rearrange the values to find Qc:

Qc = CF * Q

Qc = 0.60 * 40 SCFM = 24 SCFM of cold air flow

The temperature drop from the chart above is 86 oF.  If we have 68 oF at the inlet, then the temperature is (68 oF – 86 oF) = -18 oF.  So, from the cold end, we have 24 SCFM of air at a temperature of -18 oF.  For the hot end, we can calculate the flow and temperature as well.  From Equation 1,

Q = Qc + Qh or

Qh = Q – Qc

Qh = 40 SCFM – 24 SCFM = 16 SCFM

The temperature rise from the chart above is 119 oF.  So, with the inlet temperature at 68 oF, we get (119 oF + 68 oF) = 187 oF.  At the hot end, we have 16 SCFM of air at a temperature of 187 oF.

With the Cold Fraction and inlet air pressure, you can get specific temperatures for your application.  For cooling and heating capacities, these values can be used to calculate the correct Vortex Tube size.  If you need help in determining the proper Vortex Tube to best support your application, you can contact an Application Engineer at EXAIR.  We will be glad to help.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

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.)

Capture
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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The difference between a mold and a die? EXAIR Vortex Tubes can help in both applications.

Vortex Tubes

What is the difference between a mold and a die?  A mold is a form that shapes a liquid material into a sold piece.  It requires time for the liquid material to harden and take shape.  A die is a form that shapes a solid piece through brute force.  This can be either through stamping or through metalworking.  I will illustrate examples of both and how the Vortex Tubes were able to improve cycle times.

Mold Example: An automotive company was making plastic gas tanks through blow molding.  Liquid plastic is oozed into a mold, and just before it hardens, air is injected to create a cavity inside while the mold shapes the gas tank.  The warm tank was then placed in a fixture to cool.  Once hardened, then it could be handled and processed for the next operation.  The problem was that it took 3 minutes to harden; creating a bottleneck.  EXAIR suggested two pieces of a model 3250 Vortex Tubes to blow cold air into each cavity of the gas tanks.  This cooling process decreased the hardening time from 3 minutes to 2 minutes.  This improved productivity by 33%.

Movie Film

Die Example: A reel manufacturer was using a die stamping machine that would create the sprocket holes in the outer edge of a 35mm film.  These holes were used to advance the reel strip through printers, projectors, and processing machines.  The stamping die would heat up from the brute force of the cutting edge making the hole.  This would cause issues with the quality of the plastic film reel.  For this application, EXAIR recommended the model 5315 Cold Gun System.  This product is a modified version of the Vortex Tube that includes a magnetic base, muffler, and a dual flexible outlet hose.  They would blow the cold air on both sides of the die to keep them cool.  They were able to increase speeds and also noticed that the die stayed sharper 20% longer before they had to be reworked.

1/4 ton of refrigeration in the palm of your hand

Both customers were intrigued with the EXAIR Vortex Tubes as they can generate cold air by only using compressed air.  They do not use refrigerants, moving parts, or motors to wear.  These simple devices are very compact and can fit into tight places.  EXAIR Vortex tubes offer cooling capacities from 275 BTU/hr to 10,200 BTU/hr.  They can be configured in different styles to best suite your application.

Whether you are using a mold or a die in your process, a Vortex Tube may benefit you.  Heat causes slowdowns and bottlenecks.  With both customers above, the EXAIR Vortex Tubes were able to increase their productivity and decrease their downtime.  If you believe that temperature is affecting your process, you can contact an Application Engineer to discuss how we can help.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

 

Photo:  Reel Film Cinema By JanBabyCreative Commons CC0 Public Domain

OSHA At 35,000 Feet

Early one morning I was on a flight to the West coast to start up a system that I had designed and built for a large food producer.  After the flight attendants had passed out our first beverage and snack I struck up a conversation with the passenger next to me.  We engaged in the typical banter about how hilarious it is to watch some passengers try to stuff an oversized bag into the overhead compartment and ultimately have to check it.

I then asked the reason for her trip and she explained that she worked for OSHA and had conducted a study on flight crew safety and was in route to give her report on the findings.  I was naturally intrigued and asked her what the risks were for a flight crew other than the obvious perils of being 35,000 Ft. above the ground for long periods of time.

Her reply was radiation exposure from the sun!  I had never considered that flight crews spend long periods of time above the thickest layer of our atmosphere.  Flight crews are exposed to significantly greater amounts of radiation compared to us folks who are on the ground more and consequently develop certain health conditions at a higher rate than the general population.

While EXAIR can’t help you with radiation exposure, we can bring you into OSHA compliance with noise, OSHA Standard 29 CFR – 1910.95 (a).

This standard is concerned with the level of noise that personnel are exposed to over a given period of time.  Often times in plants compressed air noise exceeds the OSHA noise level requirements which unfortunately results in hearing loss.  Noisy air blow-offs can produce noise in excess of 100 dBA.  Studies have proven that noise levels that are sustained for varying periods of time can ultimately result in permanent hearing loss.  Similar to the way flight crews are exposed to the radiation, some employess may not realize they are being exposed to a harmful level of noise from compressed air usage.  This is why OSHA generated the standard that has allowable limits for sustained noise levels in order to mitigate the risks for personnel in the area.  Utilizing EXAIR Super Air Nozzles the noise can be reduced to only 74 dBA.  EXAIR Engineered Air Nozzles reduce the noise without losing the hard hitting force.

dBA Chart

EXAIR also meets OSHA Standard 29 CFR 1910.242(b) for “Dead End Pressure”. This standard addresses how dangerous compressed air can be when the outlet pressure of a hole, hose or open pipe is higher than 30 PSIG (2 Bar).  If the opening is blocked (dead-ended) into any part of the body, air could enter the bloodstream through the skin.  This may result in serious injury.  All EXAIR Nozzles and Jets are designed for safety and can’t be dead-ended into the skin therefore can be safely operated above the 30 PSIG (2 Bar) limit.

sag-osha-compliant

If you would like to discuss noise levels, dead end pressure or any of EXAIR’s engineered solutions, I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer
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