X-Message-Number: 22161
From: "Igor Artyuhov" <>
References: <>
Subject: Re: Propane
Date: Tue, 8 Jul 2003 16:45:13 +0400

Propane seems to be too flammable for practical purposes.

But the idea to use some liquid other than LN2 with LN2
as a "source of cold" seems sound.



I'd propose to use Tetrafluoromethane (R14, Halocarbon-14).

It is chemically inert, inflammable and non-toxic. It's boiling
temperature is -128 C (145 K)* which is near Tg for pure water

and, I hope, below Tg for cryoprotectant's solutions. It's freezing

point is -183 C.



If use it with a recuperation system, the cost will not be critical.



With best regards, Igor Artyuhov.

________________

* http://www.spezialgase.de/specialgasescatalog/gase/tetrafluormethan/



 ---------------------------------------------------------------

Yvan Bozzonetti wrote to <> on 8 Jul 2003 09:00:01 -0000:

| LN2 is not the best storage liquid, for cryonics, it is too cold, the
| industrial product is more as liquid air with low oxygen content, that is
to say, LN2
| has some oxygen, a corrosive product in it. Even 100% LN2 dissolves some
air
| and get O2 loaded after some time. This would not be the case if the
| temperature could be raised.
| Solid CO2 is too hot and there is no mass produced liquefied gas at
| intermediate temperature. An electric driven system seems far too unsafe
in the long
| run, using cold gas N2 from LN2 is rather complex and don't give a good
| security, there is nearly thermal inertia if the inflow is stopped for
some hours.
| I suggest to use cooled Propane. The hot liquid would be collected at the
| surface and cooled by boiling LN2. This system would have the same thermal
| inertia that the direct LN2 storage but temperature could be controlled
between the
| boiling propane point and the solid one. Some N2 could be dumped over
propane
| so that there is no contact with air and oxygen. I don't know if such a
system
| has been studied or best tested.

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