[AR] Re: Falcon 9 flight today
- From: JMKrell@xxxxxxx
- To: arocket@xxxxxxxxxxxxx
- Date: Wed, 9 Oct 2013 19:28:45 -0400 (EDT)
Ian,
The sun supplies the radiant heat necessary to evaporate RP-1 with a
significant area open to space. Over a lengthy period of time even the radiant
heat from the night side of earth would evaporate the RP-1 open to space.
The vapor pressure of RP-1 at -100C to -200C is extremely low, molecular
flow low. You are correct that the fuel tank is a good "thermos flask". The
RP-1 freezes in the tank and the internal mass transport follows the
Boltzmann equation.
John Krell
In a message dated 10/9/2013 3:33:31 P.M. Pacific Daylight Time,
ian.woollard@xxxxxxxxx writes:
On 9 October 2013 20:22, <_JMKrell@aol.com_ (mailto:JMKrell@xxxxxxx) > wrote
1. Open a large orifice container of RP-1 in space, liquid or frozen, it
will completely evaporate.
Nope, because it's not supercritical. It would only evaporate completely
if it was supercritical. It simply doesn't have the energy to do that.
What happens is that it starts to evaporate, this loses the latent heat of
vapourisation, which, although much smaller than water, is still pretty
damn substantial. So the temperature of the RP-1 plummets, until it's well
below ambient temperature- it's not going to be at 20C, it's going to be
frozen solid, with *desperately* low vapour pressure, according to google
kerosene-type stuff will freeze out at about -40C, probably even lower than
that
in a vacuum.
Then it's going to melt at a rate determined by how quickly it's being
externally heated.
But it's typically in a big shiny aluminum vacuum vessel aka 'thermos
flask' that reflects a lot of the sunshine and the Earthshine, and it's stone
cold- and it has no significant vapour pressure to convect heat to it.
--
-Ian Woollard
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