Ammonia borane for store the hydrogen for aircrafts and rockets of future

[Angeltxilon]

Ammonia borane (H3NBH3) is a compound with properties analogous to ethane, but with a higher point of fusion. Basically ammonia borane is solid at room temperature and pressure, unlike ethane that is a gas. 

Ammonia borane has an special property: it will release hydrogen while is heating (being transformed to H2NBH2, next to HNBH) until degrade to nytrogen boride at 1000 "C.

If ammonia borane isn't degraded to nytrogen boride, it can be recharged of hydrogen.

This is a good thing, since a ammonia borane volume is able to store much more hydrogen than the same volume of liquid hydrogen.

 

Then, it could be used for build light reusable rockets, as well as compact high hydrogen density cells of cars, and like hydrogen batteries for jet engines. 

 

Currently the ammonia borane is being studied for its possible application for hydrogen batteries of future, the main problem is the production of this substance, together logistical problems derived in the extraction and recharge of hydrogen gas from it. 

 

[Iskierka]

It may be somewhat more compact, but that is an absolutely dreadful ratio of hydrogen by mass, which is the only thing aircraft or rockets care about. Methane is considerably better and nearly as workable, if you must find a way to make it denser. Nitrogen and boranes also sounds like a good combination for high toxicity and instability, though ammonia borane itself is apparently stable, you're gonna get nasties around it with repeated heating and reacting.

Edited August 27, 2017 by Iskierka

[kerbiloid]

Methane is cryogenic, so unlikely it's a good choice to store.

Kerosene, etc are (CH2)n , i.e. ((12 + 1 * 2) / 2 = 6:1)
Hydrazine is stable, non-cryogenic and rich with hydrogen ((14 * 2 + 1 * 4) / 4 = 8:1).

[YNM]

I think that the substance would only be useful for things which only requires hydrogen. Chemical rockets might not necessarily need them, which makes other things might become more attractive.

Though, the only problem I can see is the fact that they need heating. This means the efficiency is already altered from the needs to provide a heating power source.

[kerbiloid]

4 hours ago, YNM said:

Though, the only problem I can see is the fact that they need heating. This means the efficiency is already altered from the needs to provide a heating power source.

Cryogenic ones need cooling. So, a power source, too.

[Iskierka]

6 hours ago, kerbiloid said:

Methane is cryogenic, so unlikely it's a good choice to store.

Kerosene, etc are (CH2)n , i.e. ((12 + 1 * 2) / 2 = 6:1)
Hydrazine is stable, non-cryogenic and rich with hydrogen ((14 * 2 + 1 * 4) / 4 = 8:1).

The point of methane is it's only mildly cryogenic, and therefore fairly trivial to store long-term anyway. Cryogenic power requirements are, frankly, quite tiny if you plan them from the start. At 4:1 it is also probably the best ratio of hydrogen other than hydrogen itself, and high enough that it likely has better volumetric hydrogen density than most other options, despite having a low density itself.

Of course, all of these suggestions are terrible if you are looking to use hydrogen as hydrogen in-flight, as they all require considerable power and heavy machinery to extract the hydrogen in the first place, ammonia borane for the heating to extract it and then machinery to do so safely, methane or hydrazine or other reasonable-density options for the chemical plant to separate it. Given this, it's very obvious that the best option, even for very long-term flights, is to simply store it as hydrogen in a double-walled tank, if you need to use it as hydrogen. Double-walled allows you to put a vacuum layer around the main tank, from which you can pump any escaping hydrogen back into the main tank - leaking being considerably more of a problem than cooling.

Storing hydrogen in something else is only useful if you only need it at the very end (transport, where the place you're delivering it can provide the machinery to extract), or if you only need very tiny amounts released slowly, such as a car, with much lower power requirements than an aircraft or rocket, and few restrictions on the mass of the fuel. Volume matters for a car, not so for a plane or rocket - but mass does matter, a lot, and you're always putting a lot of not-hydrogen in the way.

[kerbiloid]

56 minutes ago, Iskierka said:

methane is it's only mildly cryogenic

Methane's critical point is -95°C, while, say even ammonia (NH3 = (14+3)/3 = 5.7:1) can stay liquid at -33° at normal pressure.
It's an equlibrium temperature at 2.5 AU from Sun, far beyond the Mars orbit.
(But as a spaceship has heat sources at least for its crew compartment, this means that spaceship has to cool the methane tank until the Jupiter orbit.).

This means that a spaceship must actively cool its huge tanks, providing the cooler with energy, which is generated by a reactor, whose waste heat will additionally warm the ship.
Otherwise methane will keep evaporating, pressure inside the tanks will keep growing, and the ship will be permanently exhausting methane vapor throw a safety valve.

Also, methane density is 1.5..2 times less than kerosene and 3..4 times less than hydrazine, while its tanks need cryogenic insulation and strong walls, which means they will be much heavier.

So, its champion 4:1 ratio gets eaten by additional piece of metal, and turns into those 6:1 or so. And they never use the cheap methane in rockets, but kerosene.
And this is just on start. After several months of interplanetary flight kerosene and hydrazine stay where they were while methane (and oxygen) will be mostly exhausted.

On the Earth it's not a problem (more or less), though usually they prefer propane-butane mixture, which is much less cryogenic than methane.

Edited August 28, 2017 by kerbiloid

[DerekL1963]

2 minutes ago, kerbiloid said:

(But as a spaceship has heat sources at least for its crew compartment, this means that spaceship have to cool the methane tank until the Jupiter orbit.).

Here in the 21st century we've long since mastered insulation and thermal isolation.    Waaaaaay back in the 1960's they were building LOX tanks that could hold much colder LOX for years-to-decades.

[kerbiloid]

3 minutes ago, DerekL1963 said:

Here in the 21st century we've long since mastered insulation and thermal isolation.  

Here is energy conservation law. All heat, you produce, stays onboard until you spend it through radiators.

Btw, part of the heat, emitted by radiators, fall back on the ship. So, the ship is always warmer.

Edited August 28, 2017 by kerbiloid

[DerekL1963]

6 minutes ago, kerbiloid said:

Here is energy conservation law. All heat, you produce, stays onboard until you spend it through radiators.

Um, maybe in whatever universe it is you come from, but not here in this one.  As for what heat is generated onboard, well I refer you to what I wrote above.  We're already able to keep much colder material cold for extended periods without active cooling.  You vastly exaggerate what methane tanks will require.

[kerbiloid]

8 minutes ago, DerekL1963 said:

17 minutes ago, kerbiloid said:

Here is energy conservation law. All heat, you produce, stays onboard until you spend it through radiators.

Um, maybe in whatever universe it is you come from, but not here in this one.

Unless your universe has magic instead of physics, any energy produced in a ship, stays in the ship until you either convert it into another form of energy (say, electricity) or evacuate throw a cooler.
That's why ground facilities use cooling fluids, while a spaceship can only emit it through radiators.

Insulation doesn't matter here at all. It just slows down the heat exchange speed between the ship parts, allowing to emit most part of the waste heat before it significantly warms other parts of the ship.
So, it just makes the equilibrium temperature lower than it would be without the insulation, but still higher than it would be with frozen crew.

That's why they never use oxygen in flights longer than two weeks. (Buran was supposed to, and it had special oxygen tanks with mechanical skimmers inside).

Edited August 28, 2017 by kerbiloid

[YNM]

2 hours ago, kerbiloid said:

Cryogenic ones need cooling. So, a power source, too.

Perhaps if you could keep them gasseous.

After all, isn't space "cold" ?

[ChainiaC]

Not in close proximity of a star it isn't

Well space itself is about 4K IIRC, but that is not too relevant when you're being baked in solar radiation.

[DerekL1963]

1 hour ago, kerbiloid said:

Unless your universe has magic instead of physics, any energy produced in a ship, stays in the ship until you either convert it into another form of energy (say, electricity) or evacuate throw a cooler.

Here in this universe, things radiate heat without requiring radiators.  (Though radiators certainly help.)  That's why the Apollo missions used 'BBQ mode'.
 

1 hour ago, kerbiloid said:

That's why they never use oxygen in flights longer than two weeks.

Here in this universe, the Apollo CSM's LOX tanks were ground tested for over thirty days.

[kerbiloid]

50 minutes ago, YNM said:

Perhaps if you could keep them gasseous.

Gas with same density makes enormous pressure, requires strong→thick→heavy walls, and the tank would weight several times more than the fluid itself.
That's why they store fluids cold and liquid.

37 minutes ago, DerekL1963 said:

Here in this universe, things radiate heat without requiring radiators.  (Though radiators certainly help.)  

Hull is a part of radiator, too.
Those big radiator wings just have much greater area. A coolant takes most part of heat from the ship and brings it to the radiator.
Insulation just allows to emit most part of the heat before it reaches distant parts of the ships, say, tanks. Elementary physics.

Btw as the reactor (heat source) and the cabin (heat consumer) are placed at the opposite ends of the ship, cryogenic fuel tanks have to be placed exactly between the hot and the warm.

37 minutes ago, DerekL1963 said:

the Apollo CSM's LOX tanks were ground tested for over thirty days.

Flights lasted for a decade, test lasted for thirty days, Mars is several months from here.

Upd,
Btw... Apollo used Aerozine/NTO. LOX was just for breathing and fuel cells in much lesser amount, in strong balloons. And once it caused an explosion.

Edited August 28, 2017 by kerbiloid

[YNM]

5 minutes ago, kerbiloid said:

Gas with same density makes enormous pressure, requires strong→thick→heavy walls, and the tank would weight several times more than the fluid itself.
That's why they store fluids cold and liquid.

Well, in space, you only need to make things in the shade for it to be cold. To make things hot means to have a heating element, be it a raging nuclear inferno a few million kms away, or a combustion, or an overcurrent element.

Also, I thought spheres are somewhat better ? It's not quite the case in what I'm learning now, but isn't that overall ?

Edited August 28, 2017 by YNM

[kerbiloid]

12 minutes ago, YNM said:

Well, in space, you only need to make things in the shade for it to be cold.

Their equilibrium temperature will be anyway defined by the solar distance and the inner heating.

Even if the tank follows the ship separately, it will be heated by the umbrella IR radiation, until it reaches the equilibrium temperature.

Upd.
L = 4 pi sigma R² T⁴ = const.
RT² = const
T ~1/R^1/2.
Equilibrium temperature near the Earth orbit = +4°C = 277 K.
T_eq = 277 / R^1/2, where R in AU

-95°C (methane crytical point) = 178 K
R = (277/178)² = 2.4 AU.

(Crytical point is the temperature when any pressure can't keep the fluid liquid, it anyway gets gaseous).

Edited August 28, 2017 by kerbiloid

[wumpus]

If you think there's an issue storing liquid methane, you won't like the design of the James Webb telescope at all (it will die if it can't keep *helium* liquid).  Other space telescopes have been built around limited helium (kept cold by evaporation) lifespans.

Note that this implies that you can use a heatpump to pump heat into your radiators with a net cooling effect on your cold side (otherwise there is *no* way that liquid helium would stay liquid).