Larry Dighera wrote in
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I wasn't considering electric airliners yet; I was thinking more along
the lines of GA-sized aircraft. I'm still curious how venting H2 is
kept from producing an explosive atmosphere in laboratories and at the
gas plants where it is produced. Surely the technology exists...
It's burned off to prevent just such a situation.
Why would you want to heat liquid H2?
I was thinking it might be necessary to heat the LH2 so that it could
keep up with the fuel demand of the fuel-cell producing the power to
produce the motive thrust.
Stop refridgerating it? LH2 is -423F/-253C. It doesn't take much
to heat it up. That's why the tanks vent.
The reason tanks vent is because it's boiling off. It's very difficult
to insulate a tank to LH2 temperatures, so some of it boils off.
It would be interesting to know just how difficult it is to insulate a
LH2 vessel, so that the boil-off rate is reasonably slow.
I'm sure you could eliminated venting altogether with s sufficiently
strong tank and MAINTAINED crygenic cooling.
Remember Challenger? That's what happens when the tank breaches.
My recollection was that the seals on the Solid Rocket Boosters on the
sides of the big central O2-H2 tank had failed, and the hot SRB gases
had breached the big tank. I wasn't aware of an H2 venting issue.
My point was the size of the KABOOOM.
Perhaps a better example.... Hindenburg.
Ever notice the main rocket nozzles suddenly ice-up shortly after
ignition? I believe that's a result of the cold liquid combustion gases
being routed through tubing coiled around the rocket motors to keep them
from melting and assist in atomizing the gases, so that they will react
more readily. Just a guess.
You're correct.
http://www.nasa.gov/mission_pages/co...edia/cece.html
https://www.youtube.com/watch?v=5QJNnTRRLOo
Although not all rocket engines do this.
With 70% of the energy blowing out the exhaust as heat, internal
combustion engine efficiency is comparable to an incandescent lamp that
consumes ~90% of its energy usage to produce heat, and only ~10% to
produce light. LEDs, on the other hand, can be 90% more efficient than
tungsten filament lamps, and they last many times longer too.
Good analogy. But that is an example not of more efficient energy
production, but more efficient energy consumption. Although both
are needed in the grand scheme of things, IMO.
What's to say we can't find a more efficient way to consume fossil
fuels? Although it tends to sound conspiracy theory like, I think
there is some merit to the notion that more fuel efficiency in
cars is being held back for monetary reasons. It is a fact that
vehicles have been designed that get far higher MPG than you
typically find on the road. Why aren't they being sold?
For example, I just found the following on a VW diesel hybrid
capable of nearly 300 MPG.
http://hereandnow.wbur.org/2014/09/1...uel-efficiency
http://www.wired.com/2013/05/volkswagen-xl1-driven/
This leads to another point I learned myself while driving. People
race from red light to red light. Not don't get me wrong. I like
to drive fast just like anyone else. But what I learned to do is
to not make it a drag race. I still go ten over on the streets,
cruise 80-85mph on the freeway (I'm in LA). I just don't stomp
on the gas pedal to get there.
I did a comparison on this change in driving style. I increased
my MPG by at least 10% just by changing the way I accelerate.
Funny thing is, I often find myself pulling up to the same cars
at the light... those racing off the line.
It's basic physics. So unless the laws of physics go out the window....
I understand what you are saying, and I agree; the solution isn't
obvious, but it may be possible. Apparently a lot of large commercial
entities seem to think so...
I guess I'm arguing against the public perception. There's a lot
of bad info out there. I don't profess to be any kind of expert
myself, but I know what I know, otherwise I shut up. So many
people think it's a simple thing to just convert all our cars
to some other form of energy and overnight we can change the
world. Well, we can't. We've had a hundred years to develop IC
engines. It may take another hundred years to replace them. What
happens in the lab does not always translate to real-world
practical application.
Can an alternative be found? I'm sure of it.
Well, there are those who think science and basic physics are a
conspiracy to keep the truth from being revealed... But I'm not
assuming anyone here is in that camp. Yet.
Hey. Let's leave T. Cruz and Santorum out of this discussion. :-)
Hey, the other side of the aisle isn't much smarter. Two sides
of the same coin if you ask me.
hehehe... well, there's a web forum that I visit regularly that
is chock full of nutters. Needless to say my actual participation
has been decreasing over time as I realize the futility of even
existing in such an environment.
The New Dark Ages are upon us.
Brian
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