10-25-2017, 07:06 PM
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#1 (permalink)
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Not Doug
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Diesel in NASA's hydrogen fuel cell plane
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.
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10-26-2017, 12:39 AM
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#2 (permalink)
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Master EcoModder
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Measuring one by weight and the other by volume...sigh.  |
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10-26-2017, 03:45 AM
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#3 (permalink)
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Master EcoModder
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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.
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10-26-2017, 07:31 AM
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#4 (permalink)
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(:
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I can't imagine doing an "engine out" in that thing. Can you say "Auger it in"?
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10-26-2017, 11:34 AM
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#5 (permalink)
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Master EcoModder
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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!
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10-26-2017, 12:13 PM
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#6 (permalink)
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Corporate imperialist
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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?
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10-26-2017, 01:22 PM
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#7 (permalink)
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It's all about Diesel
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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.
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10-26-2017, 01:49 PM
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#8 (permalink)
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Corporate imperialist
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Japan had diesel powered fuel cells when I was over there back in 2003.
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1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost.
1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end.
2011 leaf SL, white, portable 240v CHAdeMO, trailer hitch, new batt as of 2014.
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10-26-2017, 01:57 PM
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#9 (permalink)
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It's all about Diesel
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Quote:
Originally Posted by oil pan 4
Japan had diesel powered fuel cells when I was over there back in 2003.
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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  |
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10-26-2017, 03:13 PM
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#10 (permalink)
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Master EcoModder
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Quote:
Originally Posted by cRiPpLe_rOoStEr
When I first heard of solid-oxide fuel cells, they were being tested on ethanol.
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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:
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Originally Posted by Xist
... if we reduce the lift\drag on a plane at cruise, we drastically reduce the energy needed to propel it.
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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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