Luke, Mum says you should be spending time on your thesis, not on hydrogen!
----- Original Message -----
From: "Luke Clough" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, 7 November 2000 11:40 AM
Subject: Re: performance gas!
> Craig,
>
> I'd always thought the photos of the hindenburg looked odd for hydrogen,
the flame was
> too bright, more consistant with the colors metals make when you stick
them in the
> flame of a bunsen. Also the light hydrogen should have rushed upward when
released so
> any fire ball should also rush upward. The hydrogen filled balloons we set
alight back
> in high school had no visable flame, and the heat haze signature rose very
rapidly.
>
> Hydrogen storage is important for the development of hydrogen as a fuel
for cars. It's
> a matter of what comes first the chicken or the egg. Fuel won't be at the
bowser until
> there are cars that can take it. Current storage practices include
compressed gas,
> liquified (as found in space shuttle boosters), or metal hydrides (where
hydrogen
> molecules are stored through absorbtion in metal powders. Personally I
wouldn't want
> liquified hydrogen or compressed gas bottles letting go in an accident .
Metal
> Hydrides give the highest kJ/Litre storage, about 50% more than the
liquified storage
> medium but are very heavy, still they have further room for development
both in
> kJ/Litre and kJ/kg whereas liquified doesn't. I'm quite sure internal
combustion
> engines can be relatively easily be produced for hydrogen. The major
stubling block in
> the past has been the storage aspect, and a cheap source of electricity to
produce it.
>
> As for the use of fossil fuels to produce hydrogen, it takes less energy
to produce it
> from fossil fuels than water, and fossil fuels provided a denser storage
medium for
> the hydrogen. It varies between fossil fuels but one fossil fuel molecule
can store
> enough hydrogen for many H2 molecules. However hydrogen isn't renewable
until we are
> producing it from water. If we are to go down the Fuel Cell/Electric motor
path then
> the hydrogen storage issue becomes a competition with batteries. kJ/kg,
kJ/Litre and
> efficiency ( best practice water to hydrogen is about 60-70% efficient at
the moment,
> combined with the 70% or so efficiency of fuel cells) become the issue as
the hydrogen
> is simply acting as a stable storage medium for the electricity energy
that was used
> to seperate the water.
>
> Should be very interesting over the next twenty odd years!
>
> Craig Overend wrote:
>
> > Luke,
> >
> > I really can't see the point of storing Hydrogen on board a car at the
> > moment. At one time there was a BUS in the US that was trialling running
> > on a Hydrogen IC Engine, the problem is where does it fill up. NASA has
> > used Hydrogen for years lifting the space shuttle into orbit and for the
> > electrics on board using fuel cell technology, they use it because of
> > its high energy content. I have read that GM were cooling the Hydrogen
> > to something like -218deg celcius in order to store it for use with
> > their fuel cell technology.
> > I'm just waiting for onboard Hydrogen reformers to become available for
> > use on Internal Combustion engines.
> > GM and ExxonMobil have supposedly recently developed an on-board fuel
> > processor/reformer that can extract 80% of the Hydrogen from petrol for
> > use with their fuel cell. Funny their doing research on petrol to
> > Hydrogen and not H2O huh? Problem is most current car electric motors
> > will only do ~50kW, and storing and suppling the power for that
> > continually is the problem. The new 42V system, is an improvment but
> > only for accessories still nowhere near enough for a drivetrain.
> >
> > Check out the following information I found regarding different fuels.
> >
> > -------------
> > Typical values for commercial fuels in megajoules/kilogram are [37]:-
> > Gross Nett
> > Hydrogen 141.9 120.0
> > Carbon to Carbon monoxide 10.2 -
> > Carbon to Carbon dioxide 32.8 -
> > Sulfur to sulfur dioxide 9.16 -
> > Natural Gas 53.1 48.0
> > Liquified petroleum gas 49.8 46.1
> > Aviation gasoline 46.0 44.0
> > Automotive gasoline 45.8 43.8
> > Kerosine 46.3 43.3
> > Diesel 45.3 42.5
> >
> > Obviously, for automobiles, the nett calorific value is appropriate, as
> > the water is emitted as vapour. The engine can not utilise the
> > additional energy available when the steam is condensed back to water.
> > The calorific value is the maximum energy that can be obtained from the
> > fuel by combustion, but thereality of modern SI engines is that thermal
> > efficiencies of only 20-40% may be obtained, this limit being due to
> > engineering and material constraints that prevent optimum thermal
> > conditions being used. CI engines can achieve higher thermal
> > efficiencies, usually over a wider operating range as well. Note that
> > combustion efficiencies are high, it is the thermal efficiency of the
> > engine is low due to losses. For a water-cooled SI engine with 25%
> > useful work at the crankshaft, the losses may consist of 35% (coolant),
> > 33% (exhaust), and 12% (surroundings).
> > ------------
>
--membersozdat-------------------------------------------------------
OZDAT Mailing List Please Note:-
Send (un)subscribe requests to [EMAIL PROTECTED]
Send submissions to [EMAIL PROTECTED]
No unauthorised redistribution of this email
http://www.ozdat.com/ozdatonline/index.htm
http://www.ozdat.com/ozdatonline/listindex.html
http://www.mail-archive.com/[email protected]/
---------------------------------------------------------------------
