Shit you just learned (probably from the internet.)

General Chat
1792

“10% of all electricity used by companies in Europe goes on compressing air - roughly 80 terawatt hours consumption per year.”

I’d have struggled to believe that. But it’s a direct quote from a piece in this month’s Physics World, the magazine of the UK Institute of Physics, so you’d hope they’d have checked that it’s true.

Even more remarkably, the piece goes on to talk about this project which, it’s claimed, could reduce the energy cost of compressing gas by 25%. The core idea is a novel turbine which in fact promises to improve performance across a genuinely huge range of applications - basically anything involving the interchange of energy between rotational mechanical motion and gas flow, either with the gas driving the rotor or with the rotor moving the gas.

If it delivers on its promise then the results could prove to be really important. Really.

VB

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1793

I haven’t a clue what you are talking about.

But thank you xxxx

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1794

The compressors we had at our factory cost a fortune to operate. We spent £40k upgrading them to more efficient units and it was recovered with lower power bills in under 3 yrs.

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1795

On my very first learning day at uni my very first lecture was on thermodynamics - the science of, among other things, heat engines and similar machines. The course ran through the whole first term.

Years later someone told me that the physics department did this deliberately, because thermodynamics was at the same time such hard work and (in a lot of people’s opinion) so dull that only the brand-new first years had enough enthusiasm/obedience/fear to stick with it. If they’d tried to force it down our throats any later in the course we’d have ditched it as ‘simply unbearable’.

So I’m not surprised you’re finding it impenetrable. Pretty much everyone does. Fortunately for the rest of us, a few people like Fenton are still grafting at it. If he’s right then he deserves to become very, very rich indeed.

VB

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1796

Not surprised really. A lot of effort is being put in to increasing efficiency across the board with motors/pumps/inverters etc. The food factories are out main customer and they use pneumatics and thus compressors in a big way.

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1797

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Reluctance motors ftw.

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1798

Thermodynamics. Reluctance.

Exactly.

VB

1799

Warning a tl;dr post

My only contact with ‘real’ thermodynamics came in the 80s when I was involved in a fire protection project to fit a Halon 1301 system into a climatically controlled chamber used by the MOD for testing tanks and stuff.
Halon 1301 was stored as a liquid in cylinders pressurized with hydrogen to 360psi.
It was released into an open distribution pipework system with nozzles at the end of the pipes.
The initial discharge was liquid then the Halon boiled in the pipework hit the nozzles and was a gas when it entered the risk.
The discharge had to be complete in 10 seconds.
We had rule of thumb calculators for estimating flows and pipe sizes etc but the final calcs were done by a computer programme that was all a bit complicated and used Newtonian approximations etc (way above my head). The programme had been tested in the USA where rooms had been built and systems installed and results checked.
This all worked fine for normal risks which were often computer suites which were all at constant temperature and most of our calcs were done assuming 20 deg C.

The climatic chamber however went down to -50 deg C
The boiling point of Halon 1301 is -55 deg C.
None of the computer models had ever been tested at that temperature and no one knew what would happen, if the Halon hadn’t boiled by the time it hit the first bend in the pipe would it smash the fitting off the wall? How would it affect the discharge time and its performance as an extinguishant?
We had some decent engineers in the firm, got ICI and DuPont (the two manufacturers of the gas) involved as they were very interested as well. Between the chemists, the MOD engineers and my firms engineers they realised that they didn’t have a clue. It turned out that one of the MOD engineers and one of ours had been to the same university so they made a few enquiries and we got a Professor of Thermodynamics from Imperial College involved and the Uni set up a project (Which I think the MOD paid for).
They did a load of computer modelling (made a few assumptions) and a solution was worked out.
So we built it and on the test day the great and the good all trooped off to Chertsey. It had taken them a couple of days to get the chamber down to temperature, all the monitoring gear was installed and we set the system off.
It didn’t do what it was supposed to do and tiny droplets of Halon came out of the nozzles, twinkled in the light and fell to the ground, it was quite beautiful but useless.
I enjoyed it all immensely as I was a junior member of the team and had all the fun with none of the responsibility.
Eventually after a lot more work we did it all again and it worked at -45 deg C.
The MOD changed all their testing specs so the temp was never taken below that and the manufacturers rewrote their specs and the computer programme suppliers put limits on the ranges where their product was reliable.
My boss asked me what I had learnt from the project, he listened to me and then said ’ just remember that people who do financial forecasts and anyone involved in thermodynamics are just guessers’

4 Likes
1800

My favourite book while studying for my HNC was Heat Engines by Rayner Joel and the Adiabatic cycle was the one I struggled with. Thermodynamics 1 & 2 were the A1, A2 course books I can’t recall the author. (early sixties)
The Carnot Cycle.

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1801

Phase changes are tough. You can get supercooled gases which don’t condense and liquids which don’t freeze. Until they do. Likewise superheating. We only ever dealt with equilibrium thermodynamics, and that was tough enough. But in the real world loads of stuff is not in equilibrium. The laser (strictly speaking the laser gain process driven by stimulated emission) for example, only works because it’s never in equilibrium.

VB

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1802

In a not quite wholly unrelated topic, I’ve just been reading about Ikaite and Glendonite. Ikaite is an extremely rare mineral which, uniquely, forms in very cold conditions in water. Minerals normally tend to form by either simple concentration-dependant precipitation from solutions percolating through rocks, or by differential cooling of extremely hot “solutions” of molten rock.

Ikaite is also unique in the fact that if you remove it from nearly-freezing water, it just melts away, leaving a sludge of commonplace calcium carbonate and some water. It’s not thermally unstable in the way water is, rather it’s an irreversible chemical reaction that happens to be temperature dependant.

It requires the mixing of two very specific kinds of mineral-laden water, and the mix needs to include nucleation preventers, such as phosphate ions, or again, you’ll just get CaCO3. When conditions are exactly right - and that pretty much means in one part of Ikka Fjord in Greenland - then you end-up with tall, thin natural columns or chimneys rising-up from the seafloor, as much 18m - until they reach about 2m below the surface - at which depth the winter ice pack extends downwards and knocks the tops off.

You get “fossilised” Ikaites in the form of Glendonites - these are simple calcite pseudomorphs, i.e. natural casts of long-vanished crystals of other materials, in this case Ikaite. Nearer to home, Jarrowite is a Glendonite which formed in the estuarine muds of the Tyne during the last Ice Age.

Much older ~55 million year old Glendonites in Denmark though have just been linked to volcanic activity (itself related to the Great Glen Fault - an abortive opening of the Atlantic along the line Loch Ness &seq), which though occurring during a period very warm climate, may have precipitated a series of previously undetected, localised, Early Eocene ice ages - geologically-brief episodes which were cold enough to have formed Ikaites.

…Aaaand all that’s got me thinking about some mysterious pipe-like structures in sandstones in Dorset, for which no remotely adequate explanation currently exists… The sedimentology and existing geochem is all wrong - but the structures, the age, and the underlying geological framework is highly compelling…

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1803

Meanwhile, back to music and hi-fi ,

1804

Great. All of the music will be given to SERCO. In the future we will have to listen to brass band music and the theme music to The Clangers. Or prog.

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1805

The future is bright :+1:

1806

He meant ‘do’ not ‘or’, the clangers DO prog :+1:

1807

A bung (though not in a paper bag)

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1808

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1809

8K calorie Elvis special

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1810

Fluffernutter - Peanut butter and marshmallow ewww.

1811

That could be nice…