Mixing
What is the advantage of using Helium over Nitrogen when used for pressurising LOx?
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In this Twitter post of the plumbing line diagram(left half) by LauncherSpace, one can notice that Helium is used for pressurising LOx while Nitrogen is used for pressurising Kerosene.
Why the dichotomy? Why not use the same gas, preferably the cheaper Nitrogen gas to pressurise LOx?
liquid-fuel spacecraft-development oxygen cryogenics pressure
asked 2 hours ago
karthikeyan
547213
add a comment |Â
up vote
3
down vote
favorite
In this Twitter post of the plumbing line diagram(left half) by LauncherSpace, one can notice that Helium is used for pressurising LOx while Nitrogen is used for pressurising Kerosene.
Why the dichotomy? Why not use the same gas, preferably the cheaper Nitrogen gas to pressurise LOx?
liquid-fuel spacecraft-development oxygen cryogenics pressure
asked 2 hours ago
karthikeyan
547213
2
I don't have a reference handy, but I'm pretty sure that the N2 diffuses into the LOX too much. We had a problem in the Space Shuttle integration office where the engine tag data from the test stand was always slightly worse than the flight performance. There was a strong feeling from some that the difference was because the flight vehicle used He/autogenous gas and the ground test system used N2 to pressurize the tanks.
– Organic Marble
2 hours ago
@OrganicMarble do you mean to say N2 “dissolves†in LOx? And thanks for sharing your experience. Very interesting and informative!
– karthikeyan
2 hours ago
Yes, you are right.
– Organic Marble
1 hour ago
Does the dissolved N2 bubble off at any site in the LOx plumbing line?or will it bubble off in engine and cool the gases resulting in reduced performance?
– karthikeyan
1 hour ago
@OrganicMarble - is this a good reference - dtic.mil/dtic/tr/fulltext/u2/272377.pdf? perhaps this was the one you were looking for
– karthikeyan
1 hour ago
add a comment |Â
up vote
3
down vote
favorite
up vote
3
down vote
favorite
In this Twitter post of the plumbing line diagram(left half) by LauncherSpace, one can notice that Helium is used for pressurising LOx while Nitrogen is used for pressurising Kerosene.
Why the dichotomy? Why not use the same gas, preferably the cheaper Nitrogen gas to pressurise LOx?
liquid-fuel spacecraft-development oxygen cryogenics pressure
asked 2 hours ago
karthikeyan
547213
In this Twitter post of the plumbing line diagram(left half) by LauncherSpace, one can notice that Helium is used for pressurising LOx while Nitrogen is used for pressurising Kerosene.
Why the dichotomy? Why not use the same gas, preferably the cheaper Nitrogen gas to pressurise LOx?
liquid-fuel spacecraft-development oxygen cryogenics pressure
liquid-fuel spacecraft-development oxygen cryogenics pressure
asked 2 hours ago
karthikeyan
547213
asked 2 hours ago
karthikeyan
547213
asked 2 hours ago
karthikeyan
547213
asked 2 hours ago
karthikeyan
547213
asked 2 hours ago
karthikeyan
547213
547213
2
I don't have a reference handy, but I'm pretty sure that the N2 diffuses into the LOX too much. We had a problem in the Space Shuttle integration office where the engine tag data from the test stand was always slightly worse than the flight performance. There was a strong feeling from some that the difference was because the flight vehicle used He/autogenous gas and the ground test system used N2 to pressurize the tanks.
– Organic Marble
2 hours ago
@OrganicMarble do you mean to say N2 “dissolves†in LOx? And thanks for sharing your experience. Very interesting and informative!
– karthikeyan
2 hours ago
Yes, you are right.
– Organic Marble
1 hour ago
Does the dissolved N2 bubble off at any site in the LOx plumbing line?or will it bubble off in engine and cool the gases resulting in reduced performance?
– karthikeyan
1 hour ago
@OrganicMarble - is this a good reference - dtic.mil/dtic/tr/fulltext/u2/272377.pdf? perhaps this was the one you were looking for
– karthikeyan
1 hour ago
add a comment |Â
2
I don't have a reference handy, but I'm pretty sure that the N2 diffuses into the LOX too much. We had a problem in the Space Shuttle integration office where the engine tag data from the test stand was always slightly worse than the flight performance. There was a strong feeling from some that the difference was because the flight vehicle used He/autogenous gas and the ground test system used N2 to pressurize the tanks.
– Organic Marble
2 hours ago
@OrganicMarble do you mean to say N2 “dissolves†in LOx? And thanks for sharing your experience. Very interesting and informative!
– karthikeyan
2 hours ago
Yes, you are right.
– Organic Marble
1 hour ago
Does the dissolved N2 bubble off at any site in the LOx plumbing line?or will it bubble off in engine and cool the gases resulting in reduced performance?
– karthikeyan
1 hour ago
@OrganicMarble - is this a good reference - dtic.mil/dtic/tr/fulltext/u2/272377.pdf? perhaps this was the one you were looking for
– karthikeyan
1 hour ago
2
2
I don't have a reference handy, but I'm pretty sure that the N2 diffuses into the LOX too much. We had a problem in the Space Shuttle integration office where the engine tag data from the test stand was always slightly worse than the flight performance. There was a strong feeling from some that the difference was because the flight vehicle used He/autogenous gas and the ground test system used N2 to pressurize the tanks.
– Organic Marble
2 hours ago
I don't have a reference handy, but I'm pretty sure that the N2 diffuses into the LOX too much. We had a problem in the Space Shuttle integration office where the engine tag data from the test stand was always slightly worse than the flight performance. There was a strong feeling from some that the difference was because the flight vehicle used He/autogenous gas and the ground test system used N2 to pressurize the tanks.
– Organic Marble
2 hours ago
@OrganicMarble do you mean to say N2 “dissolves†in LOx? And thanks for sharing your experience. Very interesting and informative!
– karthikeyan
2 hours ago
@OrganicMarble do you mean to say N2 “dissolves†in LOx? And thanks for sharing your experience. Very interesting and informative!
– karthikeyan
2 hours ago
Yes, you are right.
– Organic Marble
1 hour ago
Yes, you are right.
– Organic Marble
1 hour ago
Does the dissolved N2 bubble off at any site in the LOx plumbing line?or will it bubble off in engine and cool the gases resulting in reduced performance?
– karthikeyan
1 hour ago
Does the dissolved N2 bubble off at any site in the LOx plumbing line?or will it bubble off in engine and cool the gases resulting in reduced performance?
– karthikeyan
1 hour ago
@OrganicMarble - is this a good reference - dtic.mil/dtic/tr/fulltext/u2/272377.pdf? perhaps this was the one you were looking for
– karthikeyan
1 hour ago
@OrganicMarble - is this a good reference - dtic.mil/dtic/tr/fulltext/u2/272377.pdf? perhaps this was the one you were looking for
– karthikeyan
1 hour ago
add a comment |Â
1 Answer
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As suggested by OrganicMarble in a comment, nitrogen is miscible with oxygen (you can thus make liquid air). According to NASA Technical Paper 2464, this is a major concern because using "enriched air" instead of pure oxygen as the oxidizer degrades the performance of the engine:
The transfer of liquid oxygen (LOX) from a storage vessel to a rocket engine generally requires the use of a pressurizing gas at high pressures. The primary criteria for the choice of gas are low cost, safety, and immiscibility with liquid oxygen. Among the common gases, helium, nitrogen, and oxygen itself
have been considered. Helium is expensive, and oxygen is hazardous at high pressures. The remaining gas, nitrogen, unfortunately is miscible with oxygen
and causes dilution and loss of engine performance. (emphasis mine)
answered 1 hour ago
TooTea
1413
New contributor
TooTea is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Thanks for the reference and the answer!
– karthikeyan
1 hour ago
add a comment |Â
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
4
down vote
As suggested by OrganicMarble in a comment, nitrogen is miscible with oxygen (you can thus make liquid air). According to NASA Technical Paper 2464, this is a major concern because using "enriched air" instead of pure oxygen as the oxidizer degrades the performance of the engine:
The transfer of liquid oxygen (LOX) from a storage vessel to a rocket engine generally requires the use of a pressurizing gas at high pressures. The primary criteria for the choice of gas are low cost, safety, and immiscibility with liquid oxygen. Among the common gases, helium, nitrogen, and oxygen itself
have been considered. Helium is expensive, and oxygen is hazardous at high pressures. The remaining gas, nitrogen, unfortunately is miscible with oxygen
and causes dilution and loss of engine performance. (emphasis mine)
answered 1 hour ago
TooTea
1413
New contributor
TooTea is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Thanks for the reference and the answer!
– karthikeyan
1 hour ago
add a comment |Â
up vote
4
down vote
As suggested by OrganicMarble in a comment, nitrogen is miscible with oxygen (you can thus make liquid air). According to NASA Technical Paper 2464, this is a major concern because using "enriched air" instead of pure oxygen as the oxidizer degrades the performance of the engine:
The transfer of liquid oxygen (LOX) from a storage vessel to a rocket engine generally requires the use of a pressurizing gas at high pressures. The primary criteria for the choice of gas are low cost, safety, and immiscibility with liquid oxygen. Among the common gases, helium, nitrogen, and oxygen itself
have been considered. Helium is expensive, and oxygen is hazardous at high pressures. The remaining gas, nitrogen, unfortunately is miscible with oxygen
and causes dilution and loss of engine performance. (emphasis mine)
answered 1 hour ago
TooTea
1413
New contributor
TooTea is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Thanks for the reference and the answer!
– karthikeyan
1 hour ago
add a comment |Â
up vote
4
down vote
up vote
4
down vote
As suggested by OrganicMarble in a comment, nitrogen is miscible with oxygen (you can thus make liquid air). According to NASA Technical Paper 2464, this is a major concern because using "enriched air" instead of pure oxygen as the oxidizer degrades the performance of the engine:
The transfer of liquid oxygen (LOX) from a storage vessel to a rocket engine generally requires the use of a pressurizing gas at high pressures. The primary criteria for the choice of gas are low cost, safety, and immiscibility with liquid oxygen. Among the common gases, helium, nitrogen, and oxygen itself
have been considered. Helium is expensive, and oxygen is hazardous at high pressures. The remaining gas, nitrogen, unfortunately is miscible with oxygen
and causes dilution and loss of engine performance. (emphasis mine)
answered 1 hour ago
TooTea
1413
New contributor
TooTea is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
As suggested by OrganicMarble in a comment, nitrogen is miscible with oxygen (you can thus make liquid air). According to NASA Technical Paper 2464, this is a major concern because using "enriched air" instead of pure oxygen as the oxidizer degrades the performance of the engine:
The transfer of liquid oxygen (LOX) from a storage vessel to a rocket engine generally requires the use of a pressurizing gas at high pressures. The primary criteria for the choice of gas are low cost, safety, and immiscibility with liquid oxygen. Among the common gases, helium, nitrogen, and oxygen itself
have been considered. Helium is expensive, and oxygen is hazardous at high pressures. The remaining gas, nitrogen, unfortunately is miscible with oxygen
and causes dilution and loss of engine performance. (emphasis mine)
answered 1 hour ago
TooTea
1413
New contributor
TooTea is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 1 hour ago
TooTea
1413
New contributor
TooTea is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 1 hour ago
TooTea
1413
answered 1 hour ago
TooTea
1413
1413
New contributor
TooTea is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
TooTea is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
TooTea is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Thanks for the reference and the answer!
– karthikeyan
1 hour ago
add a comment |Â
Thanks for the reference and the answer!
– karthikeyan
1 hour ago
Thanks for the reference and the answer!
– karthikeyan
1 hour ago
Thanks for the reference and the answer!
– karthikeyan
1 hour ago
add a comment |Â
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2
I don't have a reference handy, but I'm pretty sure that the N2 diffuses into the LOX too much. We had a problem in the Space Shuttle integration office where the engine tag data from the test stand was always slightly worse than the flight performance. There was a strong feeling from some that the difference was because the flight vehicle used He/autogenous gas and the ground test system used N2 to pressurize the tanks.
– Organic Marble
2 hours ago
@OrganicMarble do you mean to say N2 “dissolves†in LOx? And thanks for sharing your experience. Very interesting and informative!
– karthikeyan
2 hours ago
Yes, you are right.
– Organic Marble
1 hour ago
Does the dissolved N2 bubble off at any site in the LOx plumbing line?or will it bubble off in engine and cool the gases resulting in reduced performance?
– karthikeyan
1 hour ago
@OrganicMarble - is this a good reference - dtic.mil/dtic/tr/fulltext/u2/272377.pdf? perhaps this was the one you were looking for
– karthikeyan
1 hour ago