[AR] Re: Pressurizing gasses
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Thu, 4 Aug 2016 01:10:52 -0400 (EDT)
On Wed, 3 Aug 2016, Norman Yarvin wrote:
However, "the bottom" here isn't fixed -- it effectively moves upward (!)
because GOX diffusing down through the helium condenses into the liquid...
Ah, so that's the trick. It presumes you're going to encounter a fair
bit of the problem -- GOX flowing downwards into the LOX -- and uses
that to force the helium down.
There's actually a feedback loop operating, so how much of the problem you
encounter is secondary -- the harder the helium tries to move upward, the
more GOX reaches the liquid and condenses (assuming the condensation can
keep up) and so the stronger the downward motion of the bulk gas.
Even with "bubbles" of helium accumulating on the surface, then breaking
loose and rising up toward the top of the tank, the surface helium still
will constantly be replenished -- at the cost of being nowhere near a
complete barrier, just something that ameliorates the situation.
Given favorable conditions, it's certainly possible to make GOX or GN2
pressurization work without a noncondensible gas included -- at least at
modest pressures -- because it's been done. So help from a noncondensible
gas just makes it work better and widens the range of conditions that
count as "favorable".
Henry
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