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The danger from fuel tanks rupturing is hard to intuit. Hydrogen will gasify and escape upward. But the hydrogen tanks themselves could fragment and be propelle

by Zigurd 5y ago

The danger from fuel tanks rupturing is hard to intuit. Hydrogen will gasify and escape upward. But the hydrogen tanks themselves could fragment and be propelled by the pressure in the tanks. It is an open question whether this is worse than kerosine escaping fuel tanks and pooling around a crashed plane.

someguydave 5y ago
at least kerosene burns with a visible flame…
- rbanffy 5y ago
  Noise is just one of the many reasons you were not allowed less than a couple kilometres from a shuttle launch.
- giantg2 5y ago
  Sort of a moot comparison, right? We can see a flame from kerosene, but kerosene burns slowly. We can't see a flame for hydrogen, but it is gaseous and burns so fast that it essentially detonates. Given that small timescale, that means we wouldn't be able to act on that information (seeing a flame) anyways.
  - jandrese 5y ago
    "You will be dead before you could see the flame anyway" isn't exactly a point in its favor.
    - giantg2 5y ago
      It's showing that the other person's detracting point about not seeing a flame is moot.
  - someguydave 5y ago
    hydrogen fires burning over a long period have definitely happened https://h2tools.org/lessons/liquid-hydrogen-delivery-truck-offloading-valve-failure https://h2tools.org/lessons/liquid-hydrogen-delivery-truck-o...
giantg2 5y ago
Considering the ignition temperature of kerosene is much higher, the deflagrenation of kerosene is much lower, and that the hydrogen will expand in the immediate area before/as it escapes up, I don't think there's too much of an open question. They are both bad scenarios, and the impact required to rupture suffienctly protected fuel containers on newer planes means its unlikely that the after effects playing of a role on the safety. My reply was focused why we wouldn't use this for cars and trucks. While fuel containers tend to be well protected on newer vehicles, the number of accidents on the roads still sees some ruptures/fires. The hydride tanks tend to be a better option since they will just smolder as the gas escapes slowly, compared to liquid hydrogen tanks which practically detonate either from the rapid release of the pressure or from the rapid deflagrenation (which occurs at a much lower flashpoint than gasoline).

by Zigurd 5y ago

someguydave 5y ago

at least kerosene burns with a visible flame…

rbanffy 5y ago
Noise is just one of the many reasons you were not allowed less than a couple kilometres from a shuttle launch.
giantg2 5y ago
Sort of a moot comparison, right? We can see a flame from kerosene, but kerosene burns slowly. We can't see a flame for hydrogen, but it is gaseous and burns so fast that it essentially detonates. Given that small timescale, that means we wouldn't be able to act on that information (seeing a flame) anyways.
- jandrese 5y ago
  "You will be dead before you could see the flame anyway" isn't exactly a point in its favor.
  - giantg2 5y ago
    It's showing that the other person's detracting point about not seeing a flame is moot.
- someguydave 5y ago
  hydrogen fires burning over a long period have definitely happened https://h2tools.org/lessons/liquid-hydrogen-delivery-truck-offloading-valve-failure https://h2tools.org/lessons/liquid-hydrogen-delivery-truck-o...

giantg2 5y ago

Considering the ignition temperature of kerosene is much higher, the deflagrenation of kerosene is much lower, and that the hydrogen will expand in the immediate area before/as it escapes up, I don't think there's too much of an open question. They are both bad scenarios, and the impact required to rupture suffienctly protected fuel containers on newer planes means its unlikely that the after effects playing of a role on the safety. My reply was focused why we wouldn't use this for cars and trucks. While fuel containers tend to be well protected on newer vehicles, the number of accidents on the roads still sees some ruptures/fires. The hydride tanks tend to be a better option since they will just smolder as the gas escapes slowly, compared to liquid hydrogen tanks which practically detonate either from the rapid release of the pressure or from the rapid deflagrenation (which occurs at a much lower flashpoint than gasoline).