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