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Molecular Helium gas is injected into a hot liquid (plastic, rubber, etc.) at high pressure. Bubbles are ejected at the liquid-surface interface of various sizes influenced by nozzle design and gas velocity, etc. Some of these bubbles should be LTA and could be harvested (?vacuumed...screened for size?).
The liquid-helium bubbles solidify at STP and the encapsulated Helium is then at partial-pressure which further reduces the perfect bubble's weight. Only the selected "perfect" bubbles are harvested. The heavier bubbles return to the liquid. These LTA microspheres could be used to reduce weight in any enlosed space...packaging, wings, toys, etc.
Catch-a-Bubble
http://www.onlineto...ubble-pr-17559.html
Bubbles that 'set', as required by this idea. Just add helium! [neutrinos_shadow, May 20 2008]
microbubble aerosol
microbubble_20aerosol#1101954286
shameless self promotion [xaviergisz, May 21 2008]
The kissing problem
http://plus.maths.o.../kissing/index.html
Not dodecahedra, unfortunately [nineteenthly, Feb 24 2010]
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Annotation:
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/The liquid-helium bubbles solidify at STP/ |
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The weight of the encapsulator will almost certainly offset any reduction offered by the helium. |
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{Lighter Than Air, Standard Temperature and Pressure(?)} |
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The helium would quickly diffuse outwards, methinks. Also, the bulk (adding all the particles together) surface area to volume ratio increases as you get smaller particles, so as they get smaller the weight contribution of the polymer increases and the spheres are subsequently weighed down. - |
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The dimensions of the "perfect" microspheres would be determined de facto...whatever works with the proper weight, surface tension, tensile strength, blah, blah, would be selected. They may be larger or smaller in scale depending on the material. Escape by diffusion of the small Helium molecule would need to be prevented by choice of material as well. This is tweak and fiddle science for sure! |
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You're much better off using hydrogen gas. By a factor of two, no less. |
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either way, I estimate that you'll be an order of magnitude or two away from actually getting this to work - even if you could get a nanometer-scale bubble surface film to solidify, it will be too fragile to do anything other than exist in a laboratory. Oh, an any gas light enough to have a shot at being LTA - will readily diffuse across any thin membrane. |
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It's almost like this isn't meant to work. |
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I used to work near a machine that fed helium-filled soap bubbles into a wind tunnel. The bubbles were about one-quarter-inch across, and were supposedly neutrally-buoyant. |
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This idea proposes a solid bubble skin, which is possible, possibly, but not that hard to think of. It's hard to make happen, though. |
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The description is messy and confusing. For instance, the bubble-maker does not need to be at high-pressure. |
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I think it is intended to solidify the bubbles at a temperature slightly higher than standard, so when the helium cools it is at reduced pressure, making a partial-vacuum sphere of each bubble. |
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We've done vacuum spheres, and can say that any advantage from partial vacuum is offset by the need for extra material in the shell. There might be some slight leakage-reduction advantage to having the helium at reduced pressure, but it will still diffuse outward over time. [-] |
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(-) for use of /..blah, blah../ |
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//but it will still diffuse outward over time// |
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ummm... but what will diffuse inwards to make up for the pressure loss ? or will the capsule gradually become a vacuum over time. |
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diffusion coefficients are inversely proportional to molecular weight |
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The membrane material needs to be impermeable otherwise you would be just as well off working on a zeolite aerogel, etc.
...the high jet velocity of helium injection was simply a method for creating a greater variety of gas bubble dimensions in terms of wall thickness, diameter, etc. |
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Molecular Helium was chosen as an inert gas vs. reactive Hydrogen while accepting the real but small increase in mass. |
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Nar, high jet velocity doesn't give all bubble sizes, and getting all sizes would be wasteful, anyhow. Figure out the optimal bubble size and thickness, and design the machinery for that. |
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Hydrogen isn't all that reactive, and most resins are much more flammable than it, anyhow. |
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Everyone is saying the helium would quickly diffuse out of the bubbles, but there aren't calculations to back this up. I've had a bit of a look around but can't find the numbers to do the calculations. |
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We know that LTA helium filled 'bubbles' do exist (e.g. mylar balloons). The question is how small and long lasting can they be made. |
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It would be interesting to make metal bubbles. Metal can be formed into sheets less than 100nm thick which is approximately the same thickness as a soap bubble. Although metal is much denser than soap, it presumably has a lower gas permeability. |
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This Material idea of Helium Encapsulation is related
with other with Aerogel Vacuum Baloon posted
october 2008 here in halfbakery "idea" category
(>product>toy). |
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All this brings to mind something that my maternal
grandmother said. It was while we were watching the
snow fall in the winter of '74 (her last year; but of course
we didn't know that at the time - we all thought she was
joking about the hydrazine), standing in the East ballroom
looking out over the croquet lawn towards the drilling
platform. One of the badgers was trying to chew the
straps on my plus-fours, and Camberwell had just brought
out another tray of hot toasted muffins. |
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Granny took a long drag, held it for a while and then
turned to me, zipping her velour jumpsuit against the
chill. "Maxwell, dearest," she said to me, "what exactly
the fuck is molecular helium?" |
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//molecular Helium// umm... [edit: [MB] you beat me to it... funny how nobody caught it when this was posted though] |
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//perfect bubble// impossible in a gravity-influenced environment: the meniscus material will flow to the bottom thus unbalancing the sphere, making it pear-shaped. You're only going to get a perfect'ish sphere in microgravity or better. |
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//liquid helium bubbles// what ? |
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//reduce weight... packaging, wings, toys, etc.// then you don't need a perfect sphere anyways... you want duodecahedrons. |
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Natural Gas would probably give pretty good results: cheap, LTA, big molecule (compared to He or H2) |
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Sadly, wonderful though it would be were this a problem solvable by dodecahedra, this isn't it. It may be a version of the "kissing problem", in which case i think the answer would be a triskaidekahedron of some kind, or there's some thing about bubbles with a non-integral mean number of faces, and if that's true there's presumably an optimal packing with a mixture of different polyhedra, though whether they'd drop into place easily seems to be another question. |
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The only purpose of the science here is to sound scientific. Every bit of it is wrong or impractical. |
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Surely though, bits of aerogel heat-sealed in a helium atmosphere could be used, couldn't they? |
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//aerogel// but what would the advantage be ? over a plain old gas-bag, I mean. |
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...should have been elemental Helium, not molecular Helium. You might think of the bubble-maker as a jet of Helium gas injected upwards from the bottom of a hot bath of the substance you want to use as the bubble wall material...like plastic, rubber, etc. The jet "blows" through this material and expels bubbles of various sizes above the surface, some of which may be LTA to be removed..."harvested". Like the Catch-a Bubble idea only durable... |
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Although helium is the second most common element in the universe, it is becoming increasingly scarce here on Earth. Bone for wastefulness [-]. |
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