h a l f b a k e r yExpensive, difficult, slightly dangerous, not particularly effective... I'm on a roll.
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Quasi-aerogel
Aerogel where the gas is close to the liquid-gas transition point | |
Purpose of this would be as a refrigerant working fluid. Ideally
the aerogel will be able to be fluidised while still retaining a
cellular structure. Within the cells of aerogel, hopefully closed
pore, there is a gas that is close to it's transition
temperature.
Hopefully the outcome is a
fluid like slurry that can have its
contents vaporised and condensed without destroying the
cellular structure and the working fluid escaping.
The point of this state is that it requires a lot less energy to
pump a liquid/slurry than to pump a gas.
[link]
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Nope, I genuinely can't see the point of this. I can't see the aerogel surviving the process. If we posit that you can come up with just individual cells of aerogel, what's the point? It'll just take up space that could be used for cooling gas. |
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An aerogel's forte is as an insulator: what does that have to do with heat transfer, which is all about heat capacity ? |
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// it requires a lot less energy to pump a
liquid/slurry than to pump a gas.// Are you sure? |
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// it requires a lot less energy to pump a
liquid/slurry
than to pump a gas.// Are you sure? |
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Well, it was one of the engineering rules of thumb
that we had to memorise in processing
engineering... |
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it stands to reason also, a liquid is incompressible
so you get the movement travelling further, also
easier to maintain laminar flows. |
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The point is the efficency to pump a liquid over a
gas. Perhaps a better form would be individually
manufactured beads that are elastic. |
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Sort of an interesting idea. Not sure about this principle of liquid being easier to pump than gas. If so, the human body uses a similar mechanism with red blood cells. |
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The gas vs liquid transport is part of the process
engineering heuristics, essentially rules of thumb |
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I never trusted my thumb, always a bit shady about it. Even if is does have a digital action. |
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I suppose it has something to do with gas compressing instead of flowing. |
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// the efficency to pump a liquid over a gas. // |
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And yet, if I may rudely interject a few moments
of rational thought into this idea, you seem to
have invented something which has the viscosity
of porridge yet retains the compressibility of a gas
or, more accurately, the compressibility of a
collection of balloons. The word "foam" springs,
gazelle-like, to mind. |
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Did you get a refund on that processing
engineering course? |
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As [MB] is saying, the reason it is easier to pump a
liquid is that it is incompressible. However an
incompressible fluid is useless as a refrigerant. So
either your aerogel mixture is incompressible, in
which case it it is easy to pump but useless as a
refrigerant, or it is compressible, in which case it
is harder (owing to a higher viscosity and friction
losses) to pump than the raw gas and still less
useful than the raw gas because it is less
compressible. |
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The former would be the case with a closed cell
inelastic material, and the latter with an open cell
or elastic material. |
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See now this is an interesting concept. If you did come up with a compound that was essentially a slurry of variously sized elastic baloons filled with gas, it might well be more efficient to pump this bulk material than the gas itself. This material might also have all sorts of interesting properties relating to it's compressibility and heat transfer behaviour. It would certainly be interesting to experiment with. |
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//See now this is an interesting concept. If you
did come up with a compound that was essentially
a slurry of variously sized elastic baloons filled with
gas, it might well be more efficient to pump this
bulk material than the gas itself. This material
might also have all sorts of interesting properties
relating to it's compressibility and heat transfer
behaviour. It would certainly be interesting to
experiment with.// |
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Yes that is where I was going with it. Or ended
up.. |
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The fundamental Idea was to allow gas to be
efficiently compressed and transported via
encapsulation. Having the capsules in a liquid
phase allows isostatic pressing with little effort. |
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The testing comes in with the matrix material for
the capsules, aerogel was the first thought
because of its pore volume:total volume ratio is so
large but other things may well be more suitable,
particularly for heat and pressure transfer to the
pore cavity. |
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Ok. here's why I don't follow this idea. Let's assume you could make single cubes of aerogel at the level to contain one molecule of the gas. How are you going persuade the gas to enter the cube? The obvious way is to increase the gas pressure, but that involves pumping the gas. |
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Assuming there is a way to get the gas in without pumping, you'd have a nearly identical amount of aerogel cubes just floating around in the lower pressure side of the mechanism, which would tend to make it more bulky. |
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The closest I can get is if the gas is magnetic. |
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"Aerogel is a synthetic porous ultralight material
derived from a gel, in which the liquid component
of the gel has been replaced with a gas." |
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"...variant on this process (supercritical drying)
involves the direct injection of supercritical
carbon dioxide into the pressure vessel containing
the aerogel. The end result of either process
removes all liquid from the gel and replaces it with
gas, without allowing the gel structure to collapse
or lose volume" |
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The desired working fluid, say ammonia, could be
used instead of carbon dioxide. |
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Any way, it only works with aerogel if it has a
closed pore structure. What maybe more suitable
is perhaps micro poly styrene balls. or some sort of
elastic capsule. |
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//supercritical carbon dioxide into the pressure vessel |
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I think the "pressure vessel" there is something of a give-away. |
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Aerogel also tends to be quite fragile if I recall. |
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