
Table of Contents
Vortex flow tube: .................................................................................................................................... 3
Types of Vortex tube:.............................................................................................................................. 3
Uniform Vortex tube ........................................................................................................................... 3
Counter Flow Vortex Tube: ................................................................................................................. 3
Working................................................................................................................................................... 4
Experimental Set up for Vortex flow tube: ............................................................................................. 4
Test set up – 1: .................................................................................................................................... 5
Test set up - 2 ...................................................................................................................................... 5
Observations and Results: ...................................................................................................................... 6
Conclusion and Comments: .................................................................................................................... 6
Advantages of vortex flow tube: ............................................................................................................. 6
Disadvantages: ........................................................................................................................................ 6
Applications: ........................................................................................................................................... 7
Reference: ............................................................................................................................................... 7

List of Figures:
Figure 1: Schematic of Parallel vortex flow tube .................................................................................... 3
Figure 2: Schematic of Counter flow vortex tube ................................................................................... 3
Figure 3: Nozzle for compressed air
Figure 4: Reduced internal
diameter of smaller pipe ......................................................................................................................... 5
Figure 5: complete set up of vortex flow tube ....................................................................................... 5
Figure 6: Movable Valve ......................................................................................................................... 6


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Vortex flow tube:
The vortex tube is a device which separates a high pressure flow entering tangentially into
two low pressure flows, there by producing a temperature change. The vortex tube has no
moving parts and generally consists of a circular tube with nozzles and throttle valve. High
pressure gas enters the vortex tube tangentially through the nozzles which increase the
angular velocity and thus produces a swirl effects. There are two exits in the vortex tube.
The hot exit is located in the outer radius near the far end of the nozzle and the cold exit is
in the centre of the tube near the nozzle. The gas separated into two layers. The gas closer
to the axis has a low temperature which comes out through the hot exit.

Types of Vortex tube:
There are two types of vortex tube:
1. Uniform vortex tube
2. Counter flow vortex tube

Uniform Vortex tube
It is also called as parallel vortex tube. This type of vortex tube has both the cold and the hot
exit at the far end of nozzle in the same side. In this type of vortex tube consist of a nozzle,
vortex tube and the cold exit present concentrically with the annular hot exit. The main
application of the vortex tube are in those areas where compactness, reliability and low
equipment costs are the major factors and the operating efficiency is of no consequence.

Figure 1: Schematic of Parallel vortex flow tube

Counter Flow Vortex Tube:

Figure 2: Schematic of Counter flow vortex tube

It consists of a nozzle, vortex tube and hot outlet with a cone shaped valve which controls the
output. The cold exit is present centrally near the nozzle end. A source of compressed gas at
a high pressure enters into the vortex tube then creates a rapidly spinning vortex. The length

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of the tube is typically between 30-50 tube diameters. As the air expands down the tube, the
pressure drops the sharply to a value slightly above atmospheric pressure. Centrifugal action
will keep this constrained vortex close to the inner surface of the tube. The air that escapes
at the other end of the tube can be varied by a flow control valve, usually shaped as a cone.
The amount of air released is between 30% and 70% of the total airflow in the tube. The
remainder of the air is returned through the centre of the tube, along its axis as a counterflowing stream. Once a vortex is set up in the tube, the air near the axis cools down while the
air at periphery heats up in comparison with the inlet temperature. This phenomena is known
as temperature separation effect.

Working
1. Compressed air is passed through the nozzle in the tube and it expands and acquires
high velocity due to particular shape of the nozzle.
2. A vortex flow is created in the chamber and air travels in spiral like motion along the
periphery of the hot side. This flow is restricted by the valve.
3. When the pressure of the air near valve is made more than outside by partly closing
the valve, a reserved axial flow through the core of the hot side starts from highpressure region to low-pressure region.
4. Inside the hot tube, both inner stream of air and outer stream of air rotates with same
angular velocity.
5. However, because of the principle of the conservation of angular momentum, the
rotation of speed of the smaller vortex be expected to increase.
6. But in the vortex tube the speed of the inner vortex remains same. Angular
momentum has been lost from the inner vortex.
7. The energy that is lost from the inner vortex shows up as heat in the outer vortex.
During this process, heat transfer takes place between reversed stream and forward
stream.
8. Therefore, air stream through the core gets cooled below the inlet temperature of the
air in the vortex tube, while air stream in the forward direction gets heated up.
9. The cold stream is escaped through the diaphragm hole into the cold side, while hot
stream is passed through the opening of the valve.
10. By controlling the opening of the valve, the quantity of the cold air and its temperature
can be varied.
Cold fraction: It defines the ratio between the mass of air moving out through the cold
exit to the actual mass of air entering the vortex tube through the inlet.

Experimental Set up for Vortex flow tube:
We have fabricated the uniform/ parallel vortex flow tube. In ordered to Vortex flow tube we used
PVC pipes of the dimension given bellow.
Hot end
Cold end

Length (inch)
36.5
8


Internal Diameter (inch)
0.81
0.4

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We did number of attempts in fabricating the Vortex flow tube.

Test set up – 1:
In order to form the vortex, we need to pass the air tangentially in the larger pipe of the assembly.
For this purpose we drilled 5 small holes tangential holes in the pipe. So air will first enter the free
space in the coupling and then will pass through five holes in the pipe. To ensure air to flow in the
larger pipe we reduced the internal diameter of the smaller pipe. These two pipes are coupled using
coupler. Hole is also drilled in the coupler for the provision of nozzle. Compressed air is entered in
the nozzle through this hole.

Figure 3: Nozzle for compressed air

Figure 4: Reduced internal diameter of smaller pipe

Test set up - 2
Temperature difference between air coming from two ends was very small in the first set up. So we
tried another approached. Instead of drilling 5 holes we drilled only one tangential hole and directly
connected it to the nozzle.

Figure 5: complete set up of vortex flow tube

In order to block air at the other end of the large pipe (Hot end), we made a provision to have a
movable valve. This helps in varying the area of outlet section of the tube.


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Figure 6: Movable Valve

Observations and Results:
1. After injecting the air at the pressure of 6 bar, we found out the difference in the
temperature of the air at both the ends (around 50C).
2. This temperature difference is not noticeable or not as expected from the vortex flow
tube. As vortex flow tubes generally give the difference around 70-80 0 C.

Conclusion and Comments:
1. One reason for the failure of our set up is the air leakage. Some amount of air was
leaking from the coupling of the pipes.
3. In order to form the vortex, air must enter the pipe tangentially. Our set up might not
able to flow air tangentially in the pipe.

Advantages of vortex flow tube:
1.
2.
3.
4.
5.

It uses air as refrigerant, so there is no leakage problem.
There are no moving parts in the vortex tube
Vortex tube is simple in design and it avoids control system.
It is light in weight and requires less space.
Initial cost is low and its working expenses are also less, where compresses air is
readily available.
6. Maintenance is simple and no skilled labours are required.
7. Very simple design can easily be made at home.
8. Can cool the fluid up to 40 0C.

Disadvantages:
1. Its low COP
2. Limited capacity.
3. Small portion of the compressed air appearing as the cold air limits its wide use in
practice.

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Applications:
1. Vortex tubes are extremely small and as it produce hot as well as cold air. It may be
used in industries where both are simultaneously required.
2. Low temperatures can be obtained without any difficulty, so it is very much useful in
industries for spot cooling of electronic components.
3. It is commonly used for body cooling of the workers in mines.

Reference:
1. http://en.wikipedia.org/wiki/Vortex_tube
2. ‘Numerical Analysis in Ranque-Hilsch Vortex Tube’ by Shreetam Das
3. http://www.nptel.iitm.ac.in/


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Vortex flow tube

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