Interesting Compressed Air Application:  Cooling a Smokestack with Air Amplifiers

In some cities when you look along the skyline, you see flue stacks bellowing out plumes of white smoke.  I never paid much attention to the structure except that they were tall and in some cases very wide.  A power company contacted EXAIR about their flue stacks.  They did a temperature reading, and they found a hotspot within the wall of the stack.  To cool the hotspot, they contacted EXAIR for a solution. 

Smokestacks are large chimneys that can be from 825 feet (250m) to 1,188 feet (360m) tall and are designed to release the smoke high in the air.  As a tall structure, it is important to keep the walls stable and sound.  For this customer, they were getting a hotspot reaching a temperature of 750oF (400oC).  This was too hot, and it could cause premature issues to the construction of the stack.  They wanted to reduce the temperature to 400oF (204oC) to keep the stack from warping and degrading.  We were able to find a solution using our stainless steel Adjustable Air Amplifiers

Adjustable Air Amplifier

The area of the hotspot in their smokestack was a section around 2 feet (0.6m).  The customer fabricated a stainless-steel manifold to mount three pieces of model 6033 3” 303SS Adjustable Air Amplifiers.  The model 6033 will only use 35.2 SCFM (997 SLPM) of compressed air at 80 PSIG (5.5 bar).  With the high amplification ratio, the model 6033 can move 2,323 SCFM (65,780 SLPM) of air along the surface.  The large volume of air created good cooling capacities to reduce the hotspot temperature.  In keeping the temperature of the stack under control, they could continue operations and lessen the concern for untimely shut-downs and costly maintenance. 

By using air to cool, you can do it safely and cleanly.  Unlike fans which create turbulent flows, voids, and high noise levels, the EXAIR Air Amplifiers generates a large volume of laminar air to cool and clean.  If you would like to speak about any cooling application, you can contact an Application Engineer; even something as large as a smokestack. 

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

Photo:  Smokestack by cwiznerPixabay Licence

What is a Super Air Amplifier

When I was working summers during school years I remember working in environments that were in unsatisfactory conditions. Since I was the the new kid and did not have seniority I had to take on the jobs that nobody wanted and therefore had the less than perfect working conditions. This company had a solvent welding process that at the time used Methyl Ethyl Ketone (MEK) as the bonding agent for ABS substrates. If only they knew about Air Amplifiers then! The solvent vapors on a hot humid Summer day would build up and I had to keep up with the quota while feeling a bit dizzy and disoriented! I couldn’t even run a fan as they were nervous blowing contaminants onto the substrates before going into the paint room. This is where a Super Air Amplifier could have helped.

Air Amplifiers are used for various reasons but in the story above could have been used for ventilation and keeping a safer work environment. Along with ventilating gasses/fumes these can be used for cooling hot parts, drying wet parts, cleaning machined parts, venting weld smoke, exhausting tank fumes, distributing heat within molds/ovens (circulation) and more! Super Air Amplifiers use the Coanda effect, a basic principle of fluidics, to create air motion. Using a small amount of compressed air as the source of power, the Super Air Amplifier then pulls in a large volume of surrounding air to produce high volume, high velocity outlet flows up to 25 times greater than the compressed air source.

Air Amplifiers use the Coanda Effect to generate high flow with low consumption.

Air Amplifiers have no moving parts making them virtually maintenance free to operate. No electricity is required. The flow, vacuum and velocity are easily controlled. Gross outlet flows can be adjusted by opening or closing the compressed air gap, which determines the amount of compressed air used. Supply air pressure can also be regulated to fine tune the outlet flow to meet application needs. Both vacuum and discharge ends of the air amplifier can be ducted, making them ideal for drawing fresh air from another location, or moving smoke and fumes away.

EXAIR carries a variety of sizes and styles and will even custom make Air Amplifiers for your every need. If you have questions about Air Amplifiers and want to talk to any of of many Application Engineers please contact us by calling 800.903.9247 or visit our website at www.EXAIR.com.

Eric Kuhnash
Application Engineer
E-mail: EricKuhnash@exair.com
Twitter: Twitter: @EXAIR_EK

How to Best Apply Vortex Tube Cooling

So, you have found yourself with a little bit of a conundrum. You need to cool a part but don’t know where to start and there are so many different options to choose from. In most cases when it comes to cooling with compressed air there are two different paths you can take. First is using a large volume of air at room temperature to blow across the surface area of the product. The other option is to use cold air from a vortex tube to drop the part’s temperature. In most case a large volume of air can be used to cool things down to relatively cooler temperatures; think cooling a cup of coffee using your breath. The issue you run into is when the temperature of the room air gets closer to the temperature you want to achieve in the end. In other words, when the temperature difference between your cooling air and your desired end temperature is small there is less cooling taking place with that same volume of air.

Mini Spot Cooler cooling down a bit used in milling plastic

This can be explained by looking at the cooling power formula:

Btu/hr = 1.0746*(CFM)*(Delta T)

In this case the Delta T is the difference between the temperature that you want to cool the product down to and the temperature of the air. This means the smaller the delta T is the higher the CFM flow will need to be to counteract the effect of the temperatures are so close to one another. Here are some examples of cooling a product and you are providing 1000 CFM of air to cool it.

Btu/hr = 1.0746*(1000 CFM)*(150F – 130F)

                Btu/hr = 21,492 Btu/hr

Btu/hr = 1.0746*(1000 CFM)*(150F – 100F)

                Btu/hr = 53,730 Btu/hr

As you can see the closer the Delta T is to 0 the less Btu/hr you get. Getting this kind of CFM flow is easy if you use something like EXAIR’s Super Air Knife or Super Air Amplifier. These systems take a small amount of compressed air and entrain the surrounding ambient air to increase the volume to a large blast. Take a look at model number 120022 which is the 2” Super Air Amplifier, this unit can produce 1,023 CFM while only using 15.5 CFM at 80 psig. But when you get close to cooling the temperature down to that room temperature or below it gets much harder; which only means that the temperature of the air being used to cool needs to be dropped. Dropping the air temperature can only be accomplished by using outside means like air coolers or in this case EXAIR’s Vortex Tubes and Spot Coolers.

EXAIR Air Amplifiers use a small amount of compressed air to create a tremendous amount of air flow.

Vortex Tubes and Spot coolers have some limitations. Generally they are not thought of products that produce large volumes of air (even though we make them up to 150 SCFM). And they are best suited for smaller areas of cooling, spot cooling, if you will. However, EXAIR Vortex Tubes do have one key feature that can help compensate for the lack of volume. LOW TEMPERATURE! The vortex tube can produce temperatures lower than 0F while stile retaining a good portion of air volume from the inlet.

Sub-zero air flow with no moving parts. 3400 Series Vortex Tubes from EXAIR.

For example, let’s look at model number 3240 running at 100 psig with 70% of the air from the inlet exiting the cold side (aka 70% cold fraction). At 100 psig the 3240 will use 40 SCFM at the air inlet and will have a temperature drop of 71F. If the compressed air has a temperature of 70F that means you will be seeing a temperature of -1F. Also, when using the 70% cold fraction you will see 28 SCFM of cold air flow. Now let’s plug those numbers into the cooling power formula.

 Btu/hr = 1.0746*(28 CFM)*(150F + 1F)

                Btu/hr = 4543 Btu/hr

As you can see, using a small amount of compressed air you can still net you a good amount of cooling if the temperature is lower. All in all, the best option for cooling products down to temperatures that are above ambient temperatures is something that can produce a large volume of air. For small areas that require cooling the product down to temperatures to ambient temperature and below, use EXAIR’s Vortex Tube.

If you have questions about our Air Amplifiers and Vortex Tubes, or would like to talk about any of the quiet EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR or any Application Engineer.

Cody Biehle
Application Engineer
EXAIR Corporation
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The Battle of Cooling: Fans Vs. Air Amplifiers

So, you have a cooling application and don’t know what to choose; do you go with the age-old fan or something different. Fans are probably one of the most common items used for cooling in everyday life and chances are you have a few that are always cooling. These fans can be found in cars, at your home, in your computer, and many other places.

But there may be other items that might just blow away the competition (pun intended). This is where EXAIR’s Air Amplifiers step onto the scene. Air Amplifiers use a little bit of compressed air to entrain the surrounding ambient air to turn it into a large volume of air.

Axial Fan being used to cool down an electrical cabinet

When it comes to cooling with air, volume is key. Air cannot hold a lot of thermal energy (heat) so in order to cool something down you need a lot of it. This means that the unit that can produce the largest volume of air is going to produce more cooling. So, what is the difference between a fan and the air amplifiers and which is better?

Fans have been in use since late B.C.E. and are still in use today. Many of the fans used for cooling are centrifugal style fans which are also known as blowers. These systems use an impeller that consists of a central shaft with blades that form a circle around a central opening. Blowers produce a high volume of air at a high velocity and low pressure. Not only do blowers require significant space to install, they also require noticeable maintenance and will eventually need to be replaced. Another, and perhaps more important downside, is that a blower will increase the temperature of the outlet air which further reduces the air’s ability to absorb additional heat and effectively cool.

Super Air Amplifier Family

On the other hand, Air Amplifiers use a source of compressed air to form a thin stream of high velocity laminar flow of air to entrain the surrounding ambient air. By doing so you can create a focused blast of air for cooling. So the downside in this case is that if you do not have a source of compressed air, the Air Amplifier will not function for you. With a small amount of compressed air, Air Amplifiers will multiply the volume of air up to 25 times to produce the large volume of air needed to cool parts, films, castings and more.

Air Amplifiers are extremely inexpensive when compared to blower systems and can out perform a blower in many applications.

If you have questions about our Air Amplifiers, or would like to talk about any of the quiet EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR or any Application Engineer.

Cody Biehle
Application Engineer
EXAIR Corporation
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