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

Looking for a reliable, consistent flow of cold air, Vortex Tube is really the better way to produce it. There are no moving part, 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:

Exair 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:

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

Vivek Engineers#22, 1st Floor, 1st Cross, Adj. to IIMB Compound, Bilekahalli Indl. Area, 
Bannerghatta Road, Bangalore - 560 076.
Ph : 080 -  2648 1309, 3297 0358, 4170 1145
TeleFax : 080- 2648 1309.
E- mail : sales@vivekengineers.net , durga@vivekengineers.net

Cooling Gelatin Pills Using The Mini Cooler

Our Principal 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.egree quick release elbow connection, 1 aluminium wand ( drum not included).

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, Our Principal recommended they use Exair's 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.

Vivek Engineers#22, 1st Floor, 1st Cross, Adj. to IIMB Compound, Bilekahalli Indl. Area, 
Bannerghatta Road, Bangalore - 560 076.
Ph : 080 -  2648 1309, 3297 0358, 4170 1145
TeleFax : 080- 2648 1309.
E- mail : p.lochan@vivekengineers.net