|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
hydrogen dissolved in hydrocarbons
I googled recently that hydrogen will dissolve in hydrocarbons such as
decane when under pressure (and I can't find it again now!). It was unclear to what percentage. I'm wondering if this has been looked at for pressurized tank use since firstly, the hydrogen coming out of solution keeps the tank pressurized as the propellant is used, so helium pressurization is not required, secondly turbopumps are not required, and thirdly a decane/hydrogen mix would presumably achieve a better ISP than RP1-type fuels on their own, with all the advantages of a dense propellant. |
#2
|
|||
|
|||
hydrogen dissolved in hydrocarbons
Roger Stokes wrote:
I googled recently that hydrogen will dissolve in hydrocarbons such as decane when under pressure (and I can't find it again now!). It was unclear to what percentage. You should check the Petroleum literature. It happends in the reserviors. Sincerely Bjørn Ove |
#3
|
|||
|
|||
hydrogen dissolved in hydrocarbons
Roger Stokes wrote:
I googled recently that hydrogen will dissolve in hydrocarbons such as decane when under pressure (and I can't find it again now!). It was unclear to what percentage. You should check the Petroleum literature. It happends in the reserviors. Sincerely Bjørn Ove |
#4
|
|||
|
|||
hydrogen dissolved in hydrocarbons
In article ,
Roger Stokes wrote: I googled recently that hydrogen will dissolve in hydrocarbons such as decane when under pressure (and I can't find it again now!). It was unclear to what percentage. Unless it's fairly high pressure, I don't think you get very much of it dissolved, alas. I'm wondering if this has been looked at for pressurized tank use since firstly, the hydrogen coming out of solution keeps the tank pressurized as the propellant is used, so helium pressurization is not required, secondly turbopumps are not required, and thirdly a decane/hydrogen mix would presumably achieve a better ISP than RP1-type fuels on their own, with all the advantages of a dense propellant. Unfortunately, these are a bit contradictory -- unless you can get a *lot* of hydrogen dissolved, if it comes out to pressurize the tank, it doesn't go down into the engine to be burned. Self-pressurizing systems are appealing, but often making them work exactly right is harder than it looks. And they have the standard problem of any pressure-fed system: heavy tanks. -- MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer pointing, 10 Sept; first science, early Oct; all well. | |
#5
|
|||
|
|||
hydrogen dissolved in hydrocarbons
In article ,
Roger Stokes wrote: I googled recently that hydrogen will dissolve in hydrocarbons such as decane when under pressure (and I can't find it again now!). It was unclear to what percentage. Unless it's fairly high pressure, I don't think you get very much of it dissolved, alas. I'm wondering if this has been looked at for pressurized tank use since firstly, the hydrogen coming out of solution keeps the tank pressurized as the propellant is used, so helium pressurization is not required, secondly turbopumps are not required, and thirdly a decane/hydrogen mix would presumably achieve a better ISP than RP1-type fuels on their own, with all the advantages of a dense propellant. Unfortunately, these are a bit contradictory -- unless you can get a *lot* of hydrogen dissolved, if it comes out to pressurize the tank, it doesn't go down into the engine to be burned. Self-pressurizing systems are appealing, but often making them work exactly right is harder than it looks. And they have the standard problem of any pressure-fed system: heavy tanks. -- MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer pointing, 10 Sept; first science, early Oct; all well. | |
#6
|
|||
|
|||
hydrogen dissolved in hydrocarbons
Roger I can't find it again now!
Basically the same forum, 11 years ago: http://www-2.cs.cmu.edu/afs/cs.cmu.e.../mnr/st/std134 Paul Dietz: Paul BTW, it looks like the mole fraction of hydrogen or helium that would Paul dissolve in propane at 298 K and 7.5 MPa are about 6% and 3%, Paul respectively. Roger I'm wondering if this has been looked at for pressurized tank Roger use I love this idea. But I don't see quite how to make it work. For the hydrogen or helium to come out of solution at any significant rate, you'd need the tank pressure to be quite a bit lower than equilibrium. Does this imply a big drop in pressure right at launch (extra tank weight)? Or a big rise in temperature, right at launch? And it seems that the fluid would cool a fair bit as the hydrogren boiled. Also, as the tanks empty the fuel/hydrogen proportion would change. All these things will make pressure regulation tough. And hydrogen boiling out as the fuel travels from tank, through cooling jacket, into the injectors sounds like it would make the engine operation uneven. There is also the issue of throwing extra helium into the combustion chamber from the LOX tank, but I'm going to guess that it will have a positive but negligable effect on ISP from lowering the average molecular weight of the exhaust. Now how do I find out helium solubility in LOX? For small rockets, a simplified tank pressurization scheme would be very nice. |
#7
|
|||
|
|||
hydrogen dissolved in hydrocarbons
Roger I can't find it again now!
Basically the same forum, 11 years ago: http://www-2.cs.cmu.edu/afs/cs.cmu.e.../mnr/st/std134 Paul Dietz: Paul BTW, it looks like the mole fraction of hydrogen or helium that would Paul dissolve in propane at 298 K and 7.5 MPa are about 6% and 3%, Paul respectively. Roger I'm wondering if this has been looked at for pressurized tank Roger use I love this idea. But I don't see quite how to make it work. For the hydrogen or helium to come out of solution at any significant rate, you'd need the tank pressure to be quite a bit lower than equilibrium. Does this imply a big drop in pressure right at launch (extra tank weight)? Or a big rise in temperature, right at launch? And it seems that the fluid would cool a fair bit as the hydrogren boiled. Also, as the tanks empty the fuel/hydrogen proportion would change. All these things will make pressure regulation tough. And hydrogen boiling out as the fuel travels from tank, through cooling jacket, into the injectors sounds like it would make the engine operation uneven. There is also the issue of throwing extra helium into the combustion chamber from the LOX tank, but I'm going to guess that it will have a positive but negligable effect on ISP from lowering the average molecular weight of the exhaust. Now how do I find out helium solubility in LOX? For small rockets, a simplified tank pressurization scheme would be very nice. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Hydrogen to the Moon | Alan Erskine | Technology | 19 | November 4th 05 07:28 PM |
Would NH4OH reduce&dissolve metals such as iron in regolith? | [email protected] | Science | 3 | May 15th 04 08:37 PM |
Interstellar Hydrogen Shadow Observed by Cassini | Ron Baalke | Science | 0 | December 9th 03 02:06 AM |
Hydrogen Sulfide, Not Carbon Dioxide, May Have Caused Largest Mass Extinction | Ron Baalke | Science | 0 | November 11th 03 08:15 AM |
Concentrating hydrogen peroxide | Earl Colby Pottinger | Technology | 1 | July 28th 03 07:59 AM |