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-   -   Diesel in NASA's hydrogen fuel cell plane (https://ecomodder.com/forum/showthread.php/diesel-nasas-hydrogen-fuel-cell-plane-35774.html)

Xist 10-25-2017 06:06 PM

Diesel in NASA's hydrogen fuel cell plane
 
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Somehow people think that spoilers make cars aerodynamic. I have read many comments on here that downforce is drag.

Well, so is lift. NASA says that if we reduce the lift\drag on a plane at cruise, we drastically reduce the energy needed to propel it. Popular Mechanics explains that the huge wings are only needed for takeoff and landing, but the X-57 uses the six motors on each wing to provide lift on takeoff and landing, larger motors on each wingtip to actually propel the craft, and until battery technology improves, "you don't need hydrogen fuel to power a fuel cell—you can use diesel."

"The energy density of Hydrogen is 120MJ/kg. The energy density of gasoline is 31 MJ/liter × 3.8 liter/gallon = 117 MJ/gallon." Gasoline is 29/30ths as energy dense as diesel, so diesel is closer to hydrogen.

Stubby79 10-25-2017 11:39 PM

Measuring one by weight and the other by volume...sigh. :rolleyes:

JockoT 10-26-2017 02:45 AM

A US gallon of gas weighs 2.83 kg so you get 41 MJ/kg (link you posted says 44). Considerably less energy per kg. You could use gasoline (or diesel), you just have to pay a weight penalty.

Frank Lee 10-26-2017 06:31 AM

I can't imagine doing an "engine out" in that thing. Can you say "Auger it in"?

JockoT 10-26-2017 10:34 AM

The Electroflight, they are developing in the UK, has a handle on the panel. Pull it and it deploys a parachute for the entire aircraft!
https://www.youtube.com/watch?v=Xe1g1JrRRkY&t=4s

oil pan 4 10-26-2017 11:13 AM

That makes sense because using hydrogen fuel in any thing other than space vehicle lift is pretty stupid.

What about the weight penalty for the compressed hydrogen container or insulation for liquid hydrogen?

cRiPpLe_rOoStEr 10-26-2017 12:22 PM

When I first heard of solid-oxide fuel cells, they were being tested on ethanol. But it doesn't really surprise me to find out some tests of fuel cells with Diesel fuel.

oil pan 4 10-26-2017 12:49 PM

Japan had diesel powered fuel cells when I was over there back in 2003.

cRiPpLe_rOoStEr 10-26-2017 12:57 PM

Quote:

Originally Posted by oil pan 4 (Post 553025)
Japan had diesel powered fuel cells when I was over there back in 2003.

What else would you expect from Japan? Anyway, I'd be curious to find out why they just didn't try to make it commercially available instead of trying hydrogen. Considering that most of their animal protein intake is fish and other seafood, could even rely on fish liver oil as a feedstock for biodiesel :D

jamesqf 10-26-2017 02:13 PM

Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 553018)
When I first heard of solid-oxide fuel cells, they were being tested on ethanol.

I've sometimes thought that fuel cells running on sugar would be a better solution, as it skips the whole conversion to ethanol step.

Quote:

Originally Posted by Xist
... if we reduce the lift\drag on a plane at cruise, we drastically reduce the energy needed to propel it.

Which is why most airplanes have flaps &c, and some have swing wings. They increase lift at the price of creating more drag.


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