If I had to guess then I would say that most of us probably haven't given a great deal of thought to
the inner workings of compressors have we? I mean what even is a compressor and why am I taking up
any of your valuable time talking about them? Exactly! Well, this is a very simple example of
a compressor and what I'm demonstrating now is perhaps one of the stupidest things you can do
with a.. OW! Thankfully history is littered with people much smarter than me who understand the far
more useful potential that these sorts of devices hold, not just for pushing air into bicycle tyres,
which is of course what this thing's really designed for, but a multitude of applications
ranging from basic pumps to sophisticated air conditioning systems and all sorts of
other devices that have become the indispensable drivers of our modern society. They all need a
power source though of course. We wouldn't get much done if we relied on hand-powered devices
like this to keep our homes cool for example. And it's a lot of power. The Carbon Trust recently
calculated that air compressors of one form or another account for more than 10 percent of total
industrial energy consumption. And a lot of that energy is wasted in leakages and heat generation,
so finding ways to make compressors work better is definitely a very good idea,
not just to save money during the current global energy crisis, but perhaps more
importantly in the long term to reduce the amount of energy we use in the first place.
And now there's a new compressor design on the market that's not just potentially
revolutionary but actually literally revolutionary. Let me show you what I mean.
Hello and welcome to Just Have a Think. It's easy to think of compressors as being
a fairly modern invention but in fact they date back to at least 1588 when an Italian
engineer called Augustino Ramelli came up with what we now would call a positive displacement
compressor which he intended to be used to pump water up from underground wells.
In 1860 Ramelli's design was significantly improved by two American brothers with the
fantastic names of Francis Marion Roots and Philander Higley Roots.
Their device caught the eye of the superintendent of a local iron foundry who realized that he could
use it to blast air into his furnaces much more efficiently than his existing bellows.
The Roots brothers were smart enough to patent their design and within 10 years they'd built a
monster, 48-ton version of their Roots Blower with enough power to shove a train carrying 22 people
through a tunnel. So, you know, eat your heart out hyperloop! These guys had nailed it 160 years ago!
And just to conform to nationalistic stereotyping, it took a German engineer to optimize the design.
His name was Heinrich Krieger and in 1878 he twisted the blades of The Roots
Blower to produce a design that he successfully patented as the Schraubengeblase or screw blower.
Then in 1935 a Swedish inventor by the name of Alf Lysholm took the concept A
step further with his twin screw supercharger which led to the development of the Lysholm
Compressor design that's still widely used in all sorts of industrial applications today.
One of the challenges faced by all compressor designs is leakage. Most designs rely on
extremely accurate machining to achieve very fine tolerances between the compressing elements and
the chamber that houses them. It's what's known in the business as a 'Clearance Gap'.
A gap is essential to avoid inefficiencies from friction and costly maintenance from wear and tear
but you want that gap to be as small as possible so that only a very tiny amount of fluid is lost.
We'll come back to that challenge in a moment, but what about this new compressor design that
I mentioned earlier on? Well it's called the Lontra Blade Compressor and it's manufactured
here in the UK by a company that is unsurprisingly called LONTRA. To understand how it works I caught
up with the company's CEO Steve Lindsey via Zoom recently. Steve explained that the basic
principle of the design is essentially just my old bicycle pump bent round into a circle and he was
kind enough to lend me this scaled down model to help show the inner workings of the device.
Inside this sealed metal chamber there are two elements rotating perpendicular to each
other. The vertically rotating element has a blade attached to it that draws in a parcel
of air via a large permanently open inlet at the bottom of the chamber. As the blade continues to
rotate air fills up the entire chamber until the blade reaches this point. So that's pretty much
exactly what happens as I pull open the handle of my bicycle pump. I've now got a full chamber
of air in here. Now, here's where we get some clever geometry going on. As the blade reaches
the top point it's able to pass through this very precisely engineered slot in the perpendicular
rotating disc. But crucially, because the shape of the blade is such that it slides very snugly
through the slot, the air that's been drawn in behind it is not able to pass through,
so it's now captured in the chamber. Because the unit is in perpetually rotating motion the blade
now sweeps back around the lower half of the circle where it does two things - it draws more
air in behind it via the large lower intake port and it squeezes the air that it captured during
the previous revolution, which is precisely what happens as I push the handle of my bicycle pump
back down again. And just like in a bicycle pump, that squeezed air is now at a nice high pressure.
You'll notice there are some holes drilled into the wall of the rotating chamber. Those holes
are sealed in by the outer wall until they reach this part of the rotation where they meet a large
external opening through which the compressed air is able to escape. Again the basic principle
is not dissimilar to my bicycle pump. In my case the pump puts air into my bicycle tyres
and in the case of the Lontra blade compressor it provides compressed air for whatever application
it's bolted onto. And that's really all there is to this beautifully simple design. The two
perpendicular rotating components are mechanically linked through a gearing system so that once
everything's been correctly calibrated to ensure the blade arrives at the slot at precisely the
right moment it will always arrive at that point, at that moment, in all subsequent revolutions.
There's no back and forth motion like you're getting a reciprocating piston setup which means
there's very little wear and tear to worry about during the operational lifetime of the compressor.
An ideal pump or compressor or piston would have a very long stroke or distance of travel but with a
very small diameter in order to minimize leakage, which brings us nicely back to that clearance gap
I mentioned earlier. The trouble is if you make the piston and rods very slender and long you
tend to get all sorts of wobbliness going on that can quite quickly lead to poor tolerances
and breakage. Because the Lontra compressor is essentially a bicycle pump wrapped around into a
circle it allows you to have that highly desirable very long stroke but without the wobbliness
because all the forces are constantly being translated around the circle which as I'm sure
you know is one of nature's strongest geometric shapes. Now of course there is existing technology
like rotary compressors and screw compressors that are engineered to partially overcome the leakage
problem and they're in use in their millions all over the planet for myriad different applications.
But all of them rely on a clearance gap that only reaches its tightest point at a very narrow
intersection at the very apex of a fin or lobe. You can see that on either side of the apex the
gap drops quickly away and widens significantly. So that means you have to have extremely tight
tolerances at that very small point where you're actually achieving a seal which makes
that part of existing compressors a relatively expensive component to manufacture. By contrast
the geometry of the Lontra blade compressor means that the radius at the edge of the rotating disc
is concentric to the housing that it's rotating within. That means there's a much wider surface
area for the clearance gap to seal against, which in turn means you get a much better seal with a
much less expensive piece of machining. That might sound like a bit of a pedantic detail
but it makes a massive difference to the overall efficiency of the compressor. Lontra's technology
has already achieved energy savings of 21% at a Severn-Trent water treatment facility
where it performs the crucial function of water aeration. Even greater efficiency improvements of
around 34 percent have been achieved in industrial pneumatic conveying applications, by which I mean
blowing commodities through a network of pipes in a factory. All sorts of products from pasta
and beans to confectionery and powders and even pharmaceutical tablets are all far more easily
transported around a production facility inside enclosed plastic or metal tubes then they would
be via a conveyor belt. Imagine trying to convince all your dried cannelloni to go around a corner
without falling off the belt! Nightmare! If you can chuck it all in a plastic or metal tube and
blow it around using compressed air instead then you've got yourself zero wastage and a much more
sterile and hygienic environment to boot. And of course the Lontra system is not limited just
to those applications either. There are countless different scenarios where the efficiency of their
compressor geometry would offer very significant savings. According to Our World in Data,
energy use in industry represents more than 24 percent of global anthropogenic CO2 emissions,
and we established earlier that compressed air accounts for about 10 percent of that energy use.
So if efficiency improvements of 34% could be achieved in all industrial compressed air
applications then just that one measure alone could potentially reduce overall carbon dioxide
equivalent emissions by more than 400 million tons every year. Food for thought isn't it?
No doubt you've got your own views on the subject and you may even be working in the development
of technologies like this and therefore have some useful insights that you could share. If
you do then why not jump down to the comments section below and leave your thoughts there.
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