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Today's topics:
* Engines Made of Carbon Fiber - 2 messages, 2 authors
http://groups.google.com/group/alt.autos/t/d7d8bbe63094af32?hl=en
* HYDROGEN CARS: Another Dumb Bush Pipe-Dream You Won't See In This Lifetime! -
1 messages, 1 author
http://groups.google.com/group/alt.autos/t/d828db79c5802560?hl=en
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TOPIC: Engines Made of Carbon Fiber
http://groups.google.com/group/alt.autos/t/d7d8bbe63094af32?hl=en
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== 1 of 2 ==
Date: Thurs, Nov 19 2009 11:40 pm
From: "2.7182818284590..."
I was looking into the melting/decomposing
point of carbon fiber, and it may be as high as 2500C. This is far
higher than the inside of an engine. This maybe too optimistic.
Kevlar, which is similar to carbon fiber, decomposes at 400C. But
this is still higher than the 200C or so temperatures which develop
inside an engine (that's the upper limit on my temperature dial).
If carbon fiber can withstand temperatures as high as 2500C and if it
can be made cheaply, than an engine not requiring a cooling system is
possible. A hotter engine is a more efficient engine.
Where am I pulling the number "2500C" from? Below!
Lower-quality fiber can be manufactured using pitch or rayon as the
precursor instead of PAN. The carbon can become further enhanced, as
high modulus, or high strength carbon, by heat treatment processes.
Carbon heated in the range of 1500-2000°C (carburizing) exhibits the
highest tensile strength (820,000 Psi or 5,650 N/mm²), while carbon
fiber heated from 2500-3000°C (graphitizing) exhibits a higher
modulus
of elasticity (77,000,000 Psi or 531 kN/mm²).
== 2 of 2 ==
Date: Fri, Nov 20 2009 9:29 am
From: "benteaches@gmail.com"
On Nov 19, 11:40 pm, "2.7182818284590..." <tangent1...@gmail.com>
wrote:
> I was looking into the melting/decomposing
Better place to discuss this may be :
heatengines@yahoogroups.com
or at:
eng-tips.com
HTH
Ben
> point of carbon fiber, and it may be as high as 2500C. This is far
> higher than the inside of an engine. This maybe too optimistic.
> Kevlar, which is similar to carbon fiber, decomposes at 400C. But
> this is still higher than the 200C or so temperatures which develop
> inside an engine (that's the upper limit on my temperature dial).
> If carbon fiber can withstand temperatures as high as 2500C and if it
> can be made cheaply, than an engine not requiring a cooling system is
> possible. A hotter engine is a more efficient engine.
> Where am I pulling the number "2500C" from? Below!
> Lower-quality fiber can be manufactured using pitch or rayon as the
> precursor instead of PAN. The carbon can become further enhanced, as
> high modulus, or high strength carbon, by heat treatment processes.
> Carbon heated in the range of 1500-2000°C (carburizing) exhibits the
> highest tensile strength (820,000 Psi or 5,650 N/mm²), while carbon
> fiber heated from 2500-3000°C (graphitizing) exhibits a higher
> modulus
> of elasticity (77,000,000 Psi or 531 kN/mm²).
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TOPIC: HYDROGEN CARS: Another Dumb Bush Pipe-Dream You Won't See In This
Lifetime!
http://groups.google.com/group/alt.autos/t/d828db79c5802560?hl=en
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== 1 of 1 ==
Date: Fri, Nov 20 2009 6:15 pm
From: Dänk 1010011010
On Nov 17, 7:27 pm, Suppurating Tool <kink...@yahoo.com> wrote:
> H-car proponents state (in a mantra repeated so often that is accepted
> as gizmo gospel by many intelligent adults) that a fuel-cell vehicle's
> "only emission is water vapor." That is true, but only in a trivial
> and thoroughly misleading sense."
>
> -----------------
> ...
> Moreover, even if pollution-free hydrogen were available -- produced,
> say, by electrolysis using zero-emissions energy from wind turbines --
> you'd still need a way to move enormous amounts of it around the
> country the way gasoline is delivered now. That raises a whole new set
> of problems. Hydrogen has relatively low energy content per unit
> volume, about one-third that of natural gas or gasoline. So it would
> have to be tightly compressed, probably to thousands of pounds per
> square inch, all without leaks of the highly flammable stuff that
> could turn the corner "gas" station or family sedan into a mini-
> Hindenburg.
One possible solution to the hydrogen storage problem is to use
hydrocarbons, meaning the vehicle can use ordinary gasoline or natural
gas, using some kind of device to strip the hydrogen atoms off to be
fed into the fuel cells. In theory, the fuel cells are much more
efficient than internal combustion, meaning less gasoline would be
needed to transport the vehicle the same distance. Unfortunately, the
current cost of the necessary technologies are prohibitively
expensive.
This idea merits further study, since hydrogen produced from renewable
sources could be converted into synthetic hydrocarbons, making it
compatible with the current energy infrastructure. Assuming the
carbon comes from renewable sources like cellulose, the synthetic
gasoline would be carbon-neutral and not contribute to global warming.
> None of that is impossible. It's just stupendously difficult and
> probably pointless. That's why, for the foreseeable future, the
> hydrogen car will remain a tailpipe dream.
>
> http://www.washingtonpost.com/wp-dyn/content/article/2009/11/16/AR200...
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