Home > What is a vortex tube and how does it work?

What is a vortex tube and how does it work?

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article image A Model 3225 vortex tube keeps plastic dishwasher arms cool during ultrasonic welding

A vortex tube is a low cost, reliable and maintenance-free solution for a variety of industrial spot cooling requirements. Vortex tubes use an ordinary supply of compressed air as a power source to create two streams of air - one hot and one cold - with no moving parts. 

Vortex tubes can produce temperatures from -50°F to +260°F (-46°C to +127°C); flow rates from 1 to 150 SCFM (28 to 4248 SLPM); and refrigeration up to 10,200 Btu/hr. (2571 Kcal/hr.). Temperatures, flows and refrigeration are adjustable over a wide range using the control valve on the hot end exhaust.

Constructed of stainless steel, EXAIR vortex tubes provide years of reliable, maintenance-free operation thanks to the resistance of stainless steel to wear, corrosion and oxidation.

How vortex tubes work

Compressed air, normally 80-100 PSIG (5.5 - 6.9 bar) is ejected tangentially through a generator into the vortex spin chamber. At up to 1,000,000 RPM, this air stream heads towards the hot end where some of the air escapes through the control valve while the remaining air, still spinning, is forced back through the centre of this outer vortex. The inner stream gives off kinetic energy in the form of heat to the outer stream and exits the vortex tube as cold air. The outer stream exits the opposite end as hot air.

Controlling temperature and flow in a vortex tube

Cold airflow and temperature are easily controlled by adjusting the slotted valve in the hot air outlet. Opening the valve reduces the cold airflow and the cold air temperature while closing the valve increases the cold airflow and the cold air temperature. The percentage of air directed to the cold outlet of the vortex tube is called the ‘cold fraction’. In most applications, a cold fraction of 80% produces a combination of cold flow rate and temperature drop that maximises refrigeration output of a vortex tube. Low cold fractions (less than 50%) produce the lowest temperatures with cold airflow rate sacrificed to achieve them.

Most industrial applications such as process cooling, part cooling and chamber cooling require maximum refrigeration and utilise the EXAIR 3200 series vortex tubes. Certain cryogenic applications including cooling lab samples or circuit testing are best served by the 3400 series vortex tubes.

Setting a vortex tube is easy and involves inserting a thermometer in the cold air exhaust and setting the temperature by adjusting the valve at the hot end. Maximum refrigeration (80% cold fraction) is achieved when cold air temperature is 50°F (28°C) below compressed air temperature.

EXAIR vortex tubes are available from Compressed Air Australia .

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