Tag: venturi cooler

What’s So Great About The Adjustable Spot Cooler?

Published on by Russ BowmanLeave a comment

EXAIR Adjustable Spot Coolers are ideally suited to a number of applications that need a flow of cold air on demand. Different applications will require more or less flow, and higher or lower temperatures. Let’s say you’re trying to cool an object to ambient temperature with a Model 3825 Adjustable Spot Cooler supplied with compressed air at 100psig and 70°F, but it’s not cooling the object as fast as you’d like. You can:

  • Increase the supply pressure, if possible. With a 100psig inlet pressure to the Adjustable Spot Cooler, you’re getting 20 SCFM of cold flow, at 16°F (assuming it’s set to an 80% Cold Fraction, which is usually ideal for spot cooling.) If you can get it to 120psig, you’ll increase the cold flow from 20 SCFM (80% of the 25 SCFM it’s using at 100psig) to 23.4 SCFM (80% of the 29.3 SCFM it’ll use at 120psig). And it’ll be colder (it’ll produce air with a 55°F temperature drop @120psig, vs 54°F @100psig).
EXAIR Vortex Tube Performance Chart – this is where the above – and below – ‘facts & figures’ come from.
  • Decrease Cold Fraction. Depending on the object’s size, material(s) of construction, amount of surface area available for heat transfer, etc., you could improve the cooling rate with lower temperature air, even if there’s less of it. If it’s particularly small in relation to the cold air flow pattern, a portion of that cold air flow might pass by without removing any heat at all. So, decreasing the temperature of the cold air that IS working will increase your rate of heat transfer. This is done by turning the knob of the Temperature Control Valve:
Turning the knob (2) counterclockwise opens the Temperature Control Valve, letting more of the supply flow (1) out of the hot end (3), and less of it to flow to the cold end (4). This also lowers the temperature of the cold air flow.
  • Change the Generator. The Adjustable Spot Cooler comes with a 25 SCFM Generator installed, but 15-R and 30-R Generators are included as well. Replacing the 25 SCFM Generator with a 30 SCFM Generator makes it use 30 SCFM @100psig, but you’ll increase the cold flow from 20 SCFM to 24 SCFM, assuming you leave it set at an 80% Cold Fraction. Keep in mind, though, that you can lower the Cold Fraction to get the same amount of cold flow as you were getting from the 25 SCFM Generator, but now it’ll be colder. If you open the Temperature Control Valve to a 70% Cold Fraction, you’ll reduce the cold flow to 21 SCFM of cold flow, but now it’ll be -1°F.

Everyone here at EXAIR wants you to get the most out of our products. If you’d like to find out more about how to do that, give me a call.

Russ Bowman, CCASS

Application Engineer
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Hot Air In The Aerospace Industry

Published on by Russ BowmanLeave a comment

Mankind’s adventures in aviation began with hot air, and it’s still kind of a big deal (for one particular EXAIR customer, that is) today.

How it started: In the 1780s, two French brothers, Joseph and Étienne Montgolfier, worked in their family’s paper mill. They noticed, along with everyone else, that pieces of paper were sometimes carried airborne in billows of smoke from the fires that heated the boilers. But unlike everyone else, they became curious as to why this happened…and how they might exploit this strange phenomenon to send something more substantial than some paper scraps through the air.

After a good deal of experimentation and trips “back to the drawing board” (they thought it was the smoke, not the heat, that caused the rise for a while), they began making public demonstrations of their first successful hot-air balloons in the summer of 1783. By autumn, having flown a sheep, a duck, and a rooster in a tethered balloon (to an altitude of about 1,500 feet on a flight that lasted about 8 minutes), they constructed a balloon large enough for two humans which flew successfully for almost half an hour, to a height of 3,000 feet. Early enthusiasts who came out to witness some of these flights included King Louis XVI, Queen Marie Antoinette, and American statesman (and quite the inventor himself) Benjamin Franklin.

The Montgolfier brothers decorated their balloons with the fleur-de-lis, zodiac symbols, and portraits of the King. I think it says a lot about ballooning that nowadays we have Sylvester the Cat, Tweety Bird, and even Spider-Pig.

How it’s going: I’m not going to lie; your level of fascination with the rest of this blog will depend on how fascinating you find the phenomenon of the Vortex Tube…which was, in fact, discovered by another French inventor, Georges Ranque:

The unique physical phenomenon of the Vortex Tube principle generates cold – and hot – air instantly, and for as long – or short – a time as needed.

Most Vortex Tube applications involve the use of the cold air flow, but a number of customers do indeed use the hot air flow. A material supplier to the aircraft & aerospace industry makes a flexible, porous strand of material that, after fabrication, passes through a wash tank prior to cutting to size. They wanted to speed up the drying time, but it was impractical to use electrically powered hot air blowers or heat guns. By using an EXAIR Model 3275 Large Vortex Tube set to a 70% Cold Fraction, they’re able to blow a little over 22 SCFM of 220°F air onto the strand, which effectively dries it to their specification, quickly & safely.

The EXAIR Vortex Tube. Cold air from one end; hot air from the other. Fully adjustable. You can use either…it’s fine with us; whatever you need.

Other EXAIR products that have been notably popular in the aerospace industry are engineered Air Nozzles, Static Eliminators, Air Amplifiers, and some even use Vortex Tubes & Spot Cooling Products for their COLD air flow. If you’d like to find out more about getting the most out of your compressed air system like the folks in the aerospace industry do, give me a call.

Russ Bowman, CCASS

Application Engineer
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Utilizing EXAIR Accessories

Published on by Al WooffittLeave a comment

Here at EXAIR we are very proud of our Intelligent Compressed Air Products. We can spend a lot of time talking about our favorites (mine is the Vortex Tube). We have written many blogs about the advantages – no moving parts, little to no maintenance, meeting or exceeding OSHA safety standards for noise or dead end pressure. One thing we don’t talk as much about are the accessories that go along with and complement our products.

From left to right; a few value added accessories for your Vortex Tube: Hot Muffler, Cold Muffler, Automatic Drain Filter Separator, Oil Removal Filter, and Solenoid Valve/Thermostat Kit.

Some of the most commonly used accessories are our compressed air Filters and Regulators. We would recommend the use of these with all of our products (or even with products that aren’t even ours).
The Filter Separator will remove water, dirt and rust from your compressed air system. The 5-micron filter element will keep contaminants from plugging or damaging your compressed air product.
An Oil Removal Filter (always placed downstream of our Filter Separator) will provide even finer filtration by removing oil and solid particulate using a 0.03-micron element.
Our Pressure Regulators will enable you to select the operating pressure. At EXAIR we always recommend operating at the minimum pressure required to get the job done. Pressure Regulators allow you to do that, saving on unnecessary air consumption and allowing for dialing in the performance of EXAIR products within an application.

For some of our products, we have accessories made specifically for them. For use with our Line Vacs we have Line Vac Hose. We have Thermostats and Solenoid Valves to pair with our Cabinet Coolers, and for our Vortex Tubes we would recommend our Mufflers.
For our Air Knives we have several great offerings:
If you need an easy and reliable way to mount your Air Knife, then our Universal Air Knife Mounting System is what you are looking for.
If your application requires something longer than our stock Knives, or perhaps you need to control certain sections of the air flow independently, then our Coupling Bracket Kits are the perfect fit.
If you want to make plumbing your Air Knife easy, take a look at our Air Knife Plumbing Kits. They can be used for all Air Knives longer than 24″.

If you need to plumb many of our other Intelligent Compressed Air Products, then we have a selection of compressed air hoses and fittings that will make life easier.
Our Coiled Hoses pair well with our Safety Air Guns, allowing you to move more freely while operating.
Our Compressed Air Hoses are commonly used with our Industrial Housekeeping products to give the drum and dolly the reach needed.

If you need a way to mount or position your Air Nozzles, then we have our Magnetic Bases, Stay Set Hoses, and Swivel Fittings that can be added to make a complete set-up.

Whatever your application’s need is, or the product you’re looking for, we certainly have a range of complimentary accessory products that will make installation and adjustment easier. If you have any questions about these, or any other EXAIR product, feel free to contact us.

Al Wooffitt
Application Engineer

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Max Btu/hr or Max Cold Temperature Vortex Tube? Which is Right for your Application?

Published on by Tyler DanielLeave a comment

EXAIR’s Vortex Tubes are a low-cost, reliable, and maintenance-free solution to a variety of industrial spot cooling problems. With just an ordinary supply of compressed air, the Vortex Tube produces two streams of air: one hot and one cold. The Vortex Tube is capable of achieving a temperature drop/rise from your compressed air supply ranging from -50°F to +260°F (-46°C to +127°C). Flow rates range from 1-150 SCFM (28-4,248 SLPM) and cooling capacities of up to 10,200 Btu/hr. With all Vortex Tubes constructed of stainless steel, they’re resistant to corrosion and oxidation, ensuring you years of reliable, maintenance-free operation.

Two primary different styles of Vortex Tubes are offered: maximum refrigeration and maximum cold temperature. Tubes for maximum refrigeration have an “R” type generator installed. These tubes are optimal for most industrial applications. Model numbers containing 32XX all have an “R” generator installed and should be used at cold fractions 50% or greater. For “cryogenic” type applications such as cooling lab samples or circuit testing, the maximum cold temperature tubes are recommended. These tubes have a “C” type generator installed. Model numbers beginning with 34XX are all designed for maximum cold temperatures and should be used when the cold fraction must be set to below 50%. The difference between the two is in the volume of air at the cold end. While the 34XX tubes deliver a colder temperature, there is much less volume of cold air.

To help illustrate the difference in cooling capacity from one style of tube vs the other, let’s walk through a calculation for each. For these examples, we’ll consider our 30 SCFM style tubes (3230 for maximum refrigeration, 3430 for maximum cold temperature).

We know that both tubes will consume 30 SCFM of compressed air when supplied at 100 PSIG. We also know that for most applications, maximum refrigeration occurs around 80% cold fraction (80% of the air exhausts from the cold side of the tube, relative to the total consumption). So, for our 3230 cooling power calculation, we’ll set the tube at 80% cold fraction. At 80% cold fraction, and 100 PSIG, there will be 24 SCFM of cold air exhausting from the tube.

The next step is to determine the temperature of the air at the cold end of the tube. For this, we’ll assume a starting temperature of 70°F. We then look at the chart shown in the catalog to determine the temperature drop, at 100 PSIG, and 80% cold fraction:

Under these conditions, the net cold temperature would be 16°F (70°F – 54°F). We now know that we’ll be delivering 24 SCFM of 16°F cold air from the Model 3230 in this scenario. Next, we’ll do the very same for the Model 3430.

We know that the 34XX series tubes are designed to be used in cold fractions below 50%. Let’s assume that the 3430 in this scenario has been set to 30% cold fraction, also at 100 PSIG:

Under these conditions, the net cold temperature would be -48°F. With the tube set to 30% cold fraction, we then know that we have 9 SCFM of air at -48°F (30 SCFM x 30%). To determine the cooling capacity for each tube under these conditions, we’ll plug the values into the refrigeration formula using a target temperature of 95°F. 

1.0746 (Btu/hr constant) x SCFM of cold flow x ΔT = Btu/hr

For the Model 3230 at 80% cold fraction, the ΔT is 75°F (95°F-16°F). For the Model 3430 at 30%, the ΔT is 135°F (95°F – (-48°F).

Model 3230 – 1.0746 x 24 SCFM x 79ΔT = 2,037 Btu/hr

Model 3430 – 1.0746 x 9 SCFM x 143ΔT = 1,383 Btu/hr

While the 3430 provides a SIGNIFICANTLY colder stream of air at -48°F, the warmer air is more effective at cooling in this example due to the increase in volume that is being provided. For most applications, the maximum refrigeration style of tubes are the best fit. In applications where an EXTREMELY cold temperature is needed, that’s where we would consider using the tubes designed for maximum cold temperatures.

Feel free to reach out to an Application Engineer if you need help in selecting the proper Vortex Tube. Or, order a Cooling Kit to ship the same day from stock and have the ability to test them all out yourself in the application!

Tyler Daniel, CCASS

E-mail: TylerDaniel@EXAIR.com

Twitter: @EXAIR_TD