Xref: utzoo sci.space:11332 sci.space.shuttle:3092
Newsgroups: sci.space,sci.space.shuttle
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: In-flight liquification of air (was Re: space news from April 3 AW&ST)
Message-ID: <1989May12.162753.22579@utzoo.uucp>
Organization: U of Toronto Zoology
References: <1989May11.050951.11130@utzoo.uucp> <3961@silver.bacs.indiana.edu>
Date: Fri, 12 May 89 16:27:53 GMT

In article <3961@silver.bacs.indiana.edu> chiaravi@silver.UUCP (Lucius Chiaraviglio) writes:
>	How is liquification of air to be done without the use of horrendously
>heavy equipment and huge energy expenditure?  (It seems that both would be
>needed to liquify air, especially at the rate that would be needed.)

I don't understand all the details, but the heat exchangers Mitsubishi is
testing simply use liquid hydrogen to cool the air.  Liquid hydrogen is
the fuel anyway, so it's around, and it is a *very* good heat sink.

>	Also, since air is only 21% oxygen, storage of liquified air would be
>quite wasteful of weight and space.  Am I correct in assuming that none of the
>liquified air would be stored (all used right away), and that liquid oxygen
>for use after leaving the atmosphere would have been loaded before launch?

There has been talk of accumulating LOX on the way up, but I don't think
the Japanese are thinking of that; they just want to run the engine on
external air while they can.

>has somebody developed some light equipment for rapid separation of nitrogen
>from oxygen as well as liquifying air?

Simply enriching the liquid in oxygen, as opposed to complete separation,
should not be difficult, since liquid nitrogen boils at a lower temperature
than LOX.  In fact, with a well-adjusted heat exchanger the liquid will
probably be oxygen-enriched to begin with, as the oxygen will condense first.
-- 
Mars in 1980s:  USSR, 2 tries, |     Henry Spencer at U of Toronto Zoology
2 failures; USA, 0 tries.      | uunet!attcan!utzoo!henry henry@zoo.toronto.edu