Beezwax
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Expedient and simple production of small quantities of LOX
I want to peoduce LOX in small amounts (less than 10ml) for home chemistry. The problem is, most LOX generators are incredibly complicated and
expensive and are meant to produce much larger quantites, such as for industrial or medical purposes.
I know it's easy to cool oxygen gas with LN2, but I'm looking to make LOX without any existing liquified gas.
So i'm interested to know if anyone here is willing to brainstorm to come up with ideas of how this could be done without investing in huge machines
with tons of complicated recyclers.
I would like to start by asking if you think it could be possible to produce LOX by using conventional HE to produce extremely high pressures in
extremely durable vessels, a kind of "explosively pumped LOX generation".
[Edited on 6-23-2024 by Beezwax]
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bnull
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I suggest you start by reading F. Papanelopoulou, "Louis Paul Cailletet: The liquefaction of oxygen and the emergence of low-temperature research" (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3826198/). I remember seeing something like a compressor in one of those books on experimental
science from the late 1800s and early 1900s. George M. Hopkins' Experimental Science (https://archive.org/details/experimentalsci00hopkgoog/page/n...), maybe.
As for the use of high explosives, the main issue seems to be heat transfer. It is an adiabatic compression, so the temperature of the gas will rise.
By how much? I have no idea.
Quod scripsi, scripsi.
B. N. Ull
P.S.: Did you know that we have a Library?
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Beezwax
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Thank you very much for this quick response and for your links. I'm most appreciative.
The problem of heat transfer from an explosive source is a big one. I would like to know what you think about developing ways to transfer pressure to
a vessel without direct application of explosive gasses.
One idea I had is to use water, transmitted through a hose, powered by an explosive charge. As an example, see this bomb disposal device, which uses
a jet of water that is explosively pumped to a target through a hose:
https://www.youtube.com/watch?v=osHIh3Y_dQ8
https://m.youtube.com/watch?v=Ybxken-YU6A
This might be a way of delivering the pressure to a vessel without excess heat.
Additionally, one might use a lower temperature HE, such as AP.
I'd greatly appreciate your thoughts about this. Thanks again.
[Edited on 6-23-2024 by Beezwax]
[Edited on 6-23-2024 by Beezwax]
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bnull
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The heat transfer I was talking about (and I should have made myself more clear) was from the compressed oxygen to the vessel. But you're right,
there's also the heat from the explosive. Maybe you could use a piece made from a refractory alloy to isolate the explosive from the rest of the
device, and that leaves us with the problem of cooling the gas.
To make 10 mL (~11 g) of liquid oxygen you need about 15 L of gaseous oxygen, assuming there are no losses. I don't know what would be the size of the
device and how many cycles would be necessary to condense 15 L of gas. And the safety is also a big issue.
Quod scripsi, scripsi.
B. N. Ull
P.S.: Did you know that we have a Library?
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Alkoholvergiftung
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https://www.youtube.com/watch?v=51a7X7lblMc
You can use an Cryocooler sometimes you can get one for 600Euro.
https://www.youtube.com/watch?v=dCXkaQa53QQ&t=135s
[Edited on 23-6-2024 by Alkoholvergiftung]
Oh and they dont need much energy an 40W Cryocooler is engough for 4 liters an day.
[Edited on 23-6-2024 by Alkoholvergiftung]
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Twospoons
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If you want simple, then a pulse tube cryocooler is about as simple as it gets, mechanically. Not so simple to design though.
Other than that you are looking at a Stirling cooler (the pulse tube is a type of Stirling cooler) or the method Linde used, with a compressor,
expansion valve and regenerative heat exchanger.
Merely compressing oxygen wont get you to the liquid phase unless you also cool it below the critical temperature of -118C.
Helicopter: "helico" -> spiral, "pter" -> with wings
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Titi
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I have always be quite interested by that. Oxygen can be bought in cylinder for welding. There are 110 bars single use, and 200 bars reusable. If the
bottle is cooled with dry ice, and then opened the valve upside down, could we condense the oxygen?
I know that we would still be above critical temperature at -78, but still not far off, and gas cools when expanded. The process would be very
inefficient for sure, but I wonder if it is possible to get at least some drops of liquid.
And a side question: does adding salt to dry ice allows to reduce temperature even further as done with table salt and water ice?
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bnull
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There's the question of the cylinders surviving the cooling to minus 78 Celsius without cracking. They resist pressure at room(ish) temperature, which
not necessarily implies that they also do at -78 °C. Quite low in my safety scale, if I may say so.
Quod scripsi, scripsi.
B. N. Ull
P.S.: Did you know that we have a Library?
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unionised
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Quote: Originally posted by Beezwax  |
I would like to start by asking if you think it could be possible to produce LOX by using conventional HE to produce extremely high pressures in
extremely durable vessels, a kind of "explosively pumped LOX generation".
[Edited on 6-23-2024 by Beezwax] |
No.
https://en.wikipedia.org/wiki/Critical_point_(thermodynamics)
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Fulmen
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| Quote: Originally posted by Titi | | does adding salt to dry ice allows to reduce temperature even further as done with table salt and water ice? |
No. Dry ice will dissolve into a variety of solvents, although most will boil at a higher temperature. I know only of two solvents that will lower
the temperature, SO2 (-82C) and ethyl ether (-100C).
As for making LOX with explosives: Good luck.
We're not banging rocks together here. We know how to put a man back together.
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Mateo_swe
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Those cryocoolers with a cold end is hard to find used and the ones that are found on auctionsites are very expensive.
I would also want one to make liquid air but the cost is too much.
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