This is a counter-flow vortex tube.
Compressed gas is fed in through the tangential inlet nozzles (marked flow inlets in the diagram).
The gas spirals down the tube, producing two distinct flows. To the right of the diagram, a hot flow leaves the tube. To the left the flow is cooler than the gas at the inlet.
The relative amounts of hot and cool gas may be varied by adjusting the valve in and out.
A sketch of the flow pattern in the counter-flow tube is given next.
There is another variety of vortex tube shown below, known as the uni-flow or co-flow tube. It differs from that above in that both the hot and cold flows leave at the same end of the tube.
The uni-flow tube is generally a less efficient energy separator then the counter-flow variety.
The basic process experienced by the air passed through the vortex tube can be represented by the flow chart in the dotted box below.
Air at standard conditions is compressed and (usually) cooled back to room conditions by a laboratory compressor. The gas is expanded through the vortex tube, where in effect, the potential energy it possess as a result of being compressed is expended in producing a temperature difference between the two outlet flows.
It is often helpful to model the behaviour of the vortex tube as a closed circuit device. In this case the equipment drawn in feintly outside the dotted box must be included in the model.
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