Do you actually need to move the lox? if you are trying to keep it cold
could you perhaps do that through the skin of the vehicle/tank?
IE put a panel in good thermal contact with the tank (at the top of the
fill level perhaps to help with stratification etc) with a LN2 loop
running through it, fill your chilled lox, then switch on the lox keeper
cold device.
On 08/11/16 07:10, Doug Jones wrote:
This strikes me as a no-brainer. Ground support equipment can have nearly arbitrary mass and power demand, and simply flow cold LOX through the rocket at a rate sufficient to maintain the temperature and density at the desired point. This would also obviate the crew loading vs propellant loading debate- load props first but keep the chiller going while loading the crew. No time pressure, no political issues with NASA safety culture, no liquid helium.
XCOR has experience in LOX fill conditioning equipment that is simple, inexpensive and robust. I should give Tom a call.
Doug Jones, Chief Test Engineer
XCOR Aerospace
1325 Sabovich
Mojave CA 93501
(661) 824-4714 x117
cell 661 313-0584
On 11/7/2016 11:05 AM, Henry Spencer wrote:
eOn Mon, 7 Nov 2016, Henry Vanderbilt wrote:
The problem with that is, you can't keep subcooled LOX at stable temperature once loaded by letting some boil off. So running with subcooled LOX means a fairly rapid propellant-loading cycle - AIUI on the order of a half-hour from load start to engines lit...
There's at least one alternative: active refrigeration. Either put a heat exchanger in the tank and circulate (say) LN2 (from ground support equipment) through it, or have tank connections at both top and bottom and circulate the LOX itself through a ground heat exchanger until just before launch. It adds complications and a bit of hardware mass, but it is feasible.
(This sort of thing got looked at in some detail in the Bad Old Days, when people were seriously considering sizable rockets with liquid fluorine or FLOX as the oxidizer. Such concepts tend to come with a non-negotiable requirement that fluorine boiloff shall be zero, which means keeping the oxidizer subcooled at all times.)
Henry
