Can anyone identify this weird plumbing item from Adam Hart Davies's Science Shack programme

[Peter]

On a TV program I saw maybe a couple of years ago Adam Hart Davies was presenting called 'Science Shack'. The episode was called 'When the oil runs out'

On it he showed a weird 'plumbing' device that took hot water in one port and due to its position caused water to be spun in a small cylinder. Water was drawn off from the centre at a colder temperature than the incoming water. So it was some kind of water cooler.

Does anybody know what this item was called and have any information on how it works?

[dingbat]

Water or air ? Usually this runs on compressed air and generates hot air (and somewhat cold air).

Try searching on "Hilsch vortex tube". They're "simple" to make, but a swine to get working well (worse than hydraulic rams). The hand-filed "snail" in the middle is crucial.

[hammy1967]

[Huge]

An aqueous version of a Hilsch Vortex Tube???

[Peter]

I can't remember if he used this novel device to heat the bath or chill the champagne. I suspect it was the latter as he would have had wood to burn and heat the bath 'when the oil ran out'.

More generally I am trying to learn more about the physics of thermal stratification in water tanks. I try and imagine a column of water in a well insulated water and suitably baffled tank, I assume it is initially at a constant temperature throughout. Will it stratify over time such that the water at the top becomes hotter? Again assuming no overall energy loss.

--------------------------------- p.3, Thermal Stratification

the 1800's scientists argued whether gases in a column would stratify due to gravity and become hotter at the bottom than the top. Maxwell and Boltzmann said it would not, but Loschmidt a prominent scientist of his time [25] argued that the world would have a never-ending supply of energy this way.

[John Schmitt]

There is a critical size for the tank and heat diffusion through the walls plays its part. Up to a point, the Atlantic fits the theory, but the model seems to fall apart at about 1000m. Convection can do some puzzling things. In the real world you will need excellent insulation (probably dewar) and good control of evaporative loss, which will cool the surface layer. The short answer is that you need two tanks connected by a pipe, one over the other. Even then, I suspect the job will become rather a WOMBAT.

John Schmitt

[Alan]

The Hilsch Vortex Tube was discussed in the Yahoo Refrigerator Alternatives group.

I can't remember the outcome but I don't think it is a practical alternative to a refrigerator.

If you were interested you could join and check out the archives.

[John Schmitt]

The consensus appears to be that this is the case. The thermodynamic efficiency is rather lower than standard refrigerators and indeed lower than gas-powered or Peltier-effect refrigerators. It is an interesting toy, but that seems to be as far as it goes.

John Schmitt