A low cost, reliable, maintenance free solution to a variety of industrial spot cooling problems. Using an ordinary supply of compressed air as a power source, vortex tubes create two streams of air, one hot and one cold, with no moving parts. Vortex tubes can produce:
• Temperatures from -46° to +127°C (-50° to +260°F)
• Flow rates from 1 to 150 SCFM (28 to 4,248 SLPM)
• Refrigeration up to 10,200 Btu/hr. (2,570 Kcal/hr.)
Temperatures, flows and refrigeration are adjustable over a wide range using the control valve on the hot end exhaust.
EXAIR Vortex Tubes are constructed of stainless steel. The wear resistance of stainless steel, as well as its resistance to corrosion and oxidation, assures that EXAIR Vortex Tubes will provide years of reliable, maintenance-free operation.
How A Vortex Tube Works
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 revolves toward the hot end where some escapes through the control valve. 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. 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, or Btu/hr. (Kcal/hr.) output of a vortex tube. While low cold fractions (less than 50%) produce lowest temperatures, cold airflow volume is sacrificed to achieve them.
Most industrial applications, i.e., process cooling, part cooling, chamber cooling, require maximum refrigeration and utilise the 32XX series Vortex Tube. Certain “cryogenic” applications, i.e., cooling lab samples, circuit testing, are best served by the 34XX series Vortex Tube.
Setting a vortex tube is easy. Simply insert a thermometer in the cold air exhaust and set the temperature by adjusting the valve at the hot end. Maximum refrigeration (80% cold fraction) is achieved when cold air temperature is 28°C (50°F) below compressed air temperature.
If you are unsure of your flow and temperature requirements, we recommend the purchase of an EXAIR Cooling Kit. It contains a vortex tube, cold air muffler, air line filter and all generators required to experiment with the full range of airflows and temperatures.
EXAIR Products Using Vortex Tubes
Over the years, the basic vortex tube has been used in virtually hundreds of industrial cooling applications. A few have become so popular as to warrant the development of an “applied product” designed to suit the specific application. These products include the Adjustable Spot Cooler, Mini Cooler, Cold Gun and Cabinet Coolers.
High Temperatures
High temperature vortex tubes for ambient temperatures above 93°C (200°F) are available. Standard vortex tubes are for ambient temperatures up to 52°C (125°F). Contact CAA for details.
Pre-set Vortex Tubes
EXAIR can provide vortex tubes preset to any combination of flow and temperature desired. To prevent tampering with the desired setting, a drilled orifice that replaces the adjustable hot valve is available. For more information, please contact CAA.
The Vortex Tube performance charts below give approximate temperature drops (and rises) from inlet air temperature produced by a Vortex Tube set at each cold fraction. Assuming no fluctuation of inlet temperature or pressure, a Vortex Tube will reliably maintain temperature within ±0.5°C (±1°F).
Pressure Supply
Cold Fraction %
PSIG
20
30
40
50
60
70
80
20
62
60
56
51
44
36
28
15
25
36
50
64
83
107
40
88
85
80
73
63
52
38
21
35
52
71
92
117
147
60
104
100
93
84
73
60
46
24
40
59
80
104
132
166
80
115
110
102
92
80
66
50
25
43
63
86
113
143
180
100
123
118
110
100
86
71
54
26
45
67
90
119
151
191
120
129
124
116
104
91
74
55
26
46
69
94
123
156
195
Numbers in shaded area give temperature drop of cold air °F
Numbers in white area give temperature rise of hot air °F
Pressure Supply
Cold Fraction % (METRIC)
BAR
20
30
40
50
60
70
80
1.4
34.4
33.3
31.1
28.3
24.4
20
15.6
8.3
13.9
20
28.3
35.6
46.1
59.4
2
40.9
39.6
37.1
33.8
29.2
24
18.1
9.8
16.4
24
33.3
42.6
54.6
69.5
3
50.4
48.7
45.7
41.6
36
29.7
21.9
12
19.9
29.6
40.3
52.3
66.5
83.5
4
56.9
54.7
50.9
46.1
40
32.9
25.1
13.2
21.9
32.4
43.9
57.1
72.5
91.2
5
61.6
59
54.8
49.4
43
35.4
26.9
13.7
23.3
34.2
46.5
60.9
77.2
97.1
6
65.4
62.7
58.2
52.7
45.6
37.6
28.6
14.1
24.3
35.8
48.6
63.9
81
102.1
7
68.6
65.8
61.4
55.7
48
39.6
30
14.4
25.1
37.3
50.2
66.3
84.2
106.3
8
71.1
68.2
63.8
57.3
50
40.8
30.4
14.4
25.4
38.1
51.8
67.9
86.1
107.9
Numbers in shaded area give temperature drop of cold air °C
Numbers in white area give temperature rise of hot air °C
Back Pressure: The performance of a Vortex Tube deteriorates with back pressure on the cold air exhaust. Low back pressure, up to 2 PSIG (.1 BAR), will not change performance. 5 PSIG (.3 BAR) will change performance by approximately 2.8°C (5°F).
Filtration: The use of clean air is essential, and filtration of 25 microns or less is recommended. EXAIR filters contain a 5 micron element and are properly sized for flow.
Inlet Air Temperature: A Vortex Tube provides a temperature drop from supply air temperature (see Performance Charts above). Elevated inlet temperatures will produce a corresponding rise in cold air temperatures.
Noise Muffling: EXAIR offers mufflers for both the hot and cold air discharge. Normally, muffling is not required if the cold air is ducted.
Regulation: For best performance, use line pressures of 80 to 110 PSIG (5.5 to 7.6 BAR). Maximum pressure rating is 250 PSIG (17.2 BAR), minimum 20 PSIG (1.4 BAR).
A 1/4 ton of refrigeration in the palm of your hand!
A Model 3225 Vortex Tube keeps plastic dishwasher arms cool during ultrasonic welding.
A pair of medium vortex tubes cool a solenoid coil after a welding operation.
Vortex Tubes with Mufflers attached set chocolate in moulds.
Special high temperature vortex tubes keep a boroscope lens cool while inserted into a 650°C (1200°F) boiler porthole.
(4) Model 3250 Vortex Tubes cool the cutting knives in this pelletiser to prevent irregular shapes.
A Model 3215 Vortex Tube cools a die on a medical tube forming machine.
Application Spotlights
Cooling Vacuum Formed Parts
The Problem
A manufacturer of major appliances vacuum forms the plastic interior shell of refrigerators. The deep draw of the plastic and complex geometry left the four corners unacceptably thin. The corners would tear during assembl...
A manufacturer of toothpaste seals the ends of plastic tubes with an ultrasonic welder prior to filling. As heat built up at the sealing jaw of the welder, release of the tubes was delayed. Tubes that were too hot would n...
Automobile fuel tanks are blow moulded, then clamped to a fixture to prevent distortion during the cooling cycle. The cooling time of over 3 minutes required for each tank created a bottleneck in the production process
Air conditioner parts assembled on an automatic brazing machine must be cooled to handling temperature prior to removal. The machine was capable of brazing up to four hundred pieces per hour. However, the time required fo...
The two questions we’re most often asked about the Vortex Tube are, “How long has it been around?” and “How does the thing work?”. Following is a brief history and theory of the Vortex Tube.
The Vortex Tube was invented quite by accident in 1928. George Ranque, a French physics student, was experimenting with a vortex-type pump he had developed when he noticed warm air exhausting from one end, and cold air from the other. Ranque soon forgot about his pump and started a small firm to exploit the commercial potential for this strange device that produced hot and cold air with no moving parts. However, it soon failed and the Vortex Tube slipped into obscurity until 1945 when Rudolph Hilsch, a German physicist, published a widely read scientific paper on the device.
Much earlier, the great nineteenth century physicist, James Clerk Maxwell, postulated that since heat involves the movement of molecules, we might someday be able to get hot and cold air from the same device with the help of a “friendly little demon” who would sort out and separate the hot and cold molecules of air.
Thus, the Vortex Tube has been variously known as the “Ranque Vortex Tube”, the “Hilsch Tube”, the “Ranque-Hilsch Tube”, and “Maxwell’s Demon”. By any name, it has in recent years gained acceptance as a simple, reliable and low cost answer to a wide variety of industrial spot cooling problems.
A Vortex Tube uses compressed air as a power source, has no moving parts, and produces hot air from one end and cold air from the other. The volume and temperature of these two airstreams are adjustable with a valve built into the hot air exhaust. Temperatures as low as -46°C (-50°F) and as high as +127°C (+260°F) are possible.
Theories abound regarding the dynamics of a Vortex Tube. Here is one widely accepted explanation of the phenomenon:
Compressed air is supplied to the Vortex Tube and passes through nozzles that are tangent to an internal counterbore. These nozzles set the air in a vortex motion. This spinning stream of air turns 90° and passes down the hot tube in the form of a spinning shell, similar to a tornado. A valve at one end of the tube allows some of the warmed air to escape. What does not escape, heads back down the tube as a second vortex inside the low-pressure area of the larger vortex. This inner vortex loses heat and exhausts through the other end as cold air.
While one airstream moves up the tube and the other down it, both rotate in the same direction at the same angular velocity. That is, a particle in the inner stream completes one rotation in the same amount of time as a particle in the outer stream. However, because of the principle of conservation of angular momentum, the rotational speed of the smaller vortex might be expected to increase. (The conservation principle is demonstrated by spinning skaters who can slow or speed up their spin by extending or drawing in their arms.) But in the Vortex Tube, the speed of the inner vortex remains the same. Angular momentum has been lost from the inner vortex. The energy that is lost shows up as heat in the outer vortex. Thus the outer vortex becomes warm, and the inner vortex is cooled.
EXAIR Vortex Tubes are available in three sizes. Each size can produce a number of flow rates, as determined by a small internal part called a generator. If Btu/hr. (Kcal/hr.) requirements, or flow and temperature requirements are known, simply select the appropriate Vortex Tube according to the specification information shown below or the performance charts. Keep in mind that the vortex generators are interchangeable. If, for example, a Model 3215 Vortex Tube does not provide sufficient cooling, you need only change generators within the Vortex Tube to upgrade the flow rate from 15 to 25, 30 or 40 SCFM (425 to 708, 850 or 1133 SLPM).
Dimensions
Specifications
32XX series Vortex Tubes optimise temperature drop and airflow to produce maximum cooling power or Btu/hr. (Kcal/hr.). Specify 32XX series Vortex Tubes for most general cooling applications.
32XX Series Vortex Tube Specifications
Model
SCFM*
SLPM*
Btu/hr.**
Kcal/hr.**
Size
dBA***
3202
2
57
135
34
Small
68
3204
4
113
275
69
Small
70
3208
8
227
550
139
Small
76
3210
10
283
650
164
Medium
80
3215
15
425
1000
252
Medium
81
3225
25
708
1700
428
Medium
82
3230
30
850
2000
504
Medium
84
3240
40
1,133
2800
706
Medium
88
3250
50
1,416
3400
857
Large
94
3275
75
2,124
5100
1285
Large
96
3298
100
2,832
6800
1714
Large
96
3299
150
4,248
10,200
2570
Large
97
* SCFM (SLPM) at 100 PSIG (6.9 Bar) Inlet Pressure
** Btu/hr. (Kcal/hr.) Cooling Capacity at 100 PSIG (6.9 Bar)
*** Noise levels taken with hot and cold mufflers installed
34XX series Vortex Tubes optimise temperature drop and airflow to produce maximum cooling power or Btu/hr. (Kcal/hr.). Specify 34XX series Vortex Tubes only where temperatures below -18°C (0°F) are desired.
34XX Series Vortex Tube Specifications
Model
SCFM*
SLPM*
Btu/hr.**
Kcal/hr.**
Size
dBA***
3402
2
57
——–
——–
Small
67
3404
4
113
——–
——–
Small
69
3408
8
227
——–
——–
Small
75
3410
10
283
——–
——–
Medium
78
3415
15
425
——–
——–
Medium
80
3425
25
708
——–
——–
Medium
82
3430
30
850
——–
——–
Medium
84
3440
40
1,133
——–
——–
Medium
87
3450
50
1,416
——–
——–
Large
93
3475
75
2,124
——–
——–
Large
96
3498
100
2,832
——–
——–
Large
96
3499
150
4,248
——–
——–
Large
96
* SCFM (SLPM) at 100 PSIG (6.9 Bar) Inlet Pressure
** Not Applicable. 34XX series Vortex Tubes are not normally used in air conditioning applications
*** Noise levels taken with hot and cold mufflers installed
Models
EXAIR Cooling Kits
Kits include a Vortex Tube, all generators, cold muffler, fitting, tubing and clips to duct cold air, and filter separator (with mounting bracket)
Model
Description
BP3908
Small Cooling Kit up to 550 Btu/hr. (139 Kcal/hr.)
BP3930
Medium Cooling Kit up to 2,800 Btu/hr. (706 Kcal/hr.)
BP3998
Large Cooling Kit up to 10,200 Btu/hr. (2,570 Kcal/hr.)
Cold Muffler for 2 to 8 SCFM (57 to 227 SLPM) Small Vortex Tube
3901
Cold Muffler for 10 to 40 SCFM (283 to 1,133 SLPM) Medium Vortex Tube
3906
Cold Muffler for 50 to 150 SCFM (1,416 to 4,248 SLPM) Large Vortex Tube
3903
Hot Muffler for 2 to 40 SCFM (57 to 1,133 SLPM) Small & Medium Vortex Tube
3907
Hot Muffler for 50 to 150 SCFM (1,416 to 4,248 SLPM) Large Vortex Tube
3909
Generator Kit for 2 to 8 SCFM (57 to 227 SLPM) Small Vortex Tube
3902
Generator Kit for 10 to 40 SCFM (283 to 1,133 SLPM) Medium Vortex Tube
3910
Generator Kit for 50 to 150 SCFM (1,416 to 4,248 SLPM) Large Vortex Tube
Generator Kits ordered with a Vortex Tube include all generators for the specified tube. Permits setting the Vortex Tube for all capacities and styles. Generator Only – Specify capacity (SCFM) and style (“R” for max. refrigeration, “C” for max. cold temperature) Example: 15-R = 15 SCFM Generator for max. refrigeration 50-C = 50 SCFM Generator for max. cold temperature
Accessories
Filters, Regulators, Valves & More
With proper filtration of dirt, moisture and oil from the compressed air supply, EXAIR compressed air products will operate for years with no maintenance required. Use a 5 micron or smaller filter separator on the compressed air supply. To prevent problems associated with oil, use a 0.03 micron or smaller oil removal filter on the compressed air supply. Pressure regulators permit easy selection of the operating pressure, providing infinite control of flow, force and air consumption.