Stephen A. Lawrence writes,
> A typical IC engine requires a compression ratio of 10-1 to
> get up
> to 85% complete combustion of hydrocarbons (that's about the
> max, so
> there is usually 15% wasted off the top because of the strong
> molecular bonding of hydrocarbons)
But aren't modern engines, which happily gobble 87 octane fuel,
down in
the ballpark of 9:1 rather than 10:1? That presumably means
they're
burning _less_ than 85% of the fuel, yes?
Covering this narrow subject (complete combustion) in exact detail
would require many pages, as there are many, many variables
involved. The most important variable for complete burn, besides
compression ratio and uniformity of the charge, is the "wetted
area" i.e. the surface area of relatively cold metal which is in
contact with the fuel-air mix. This is one reason why the
"hemi-head" - the dome is better for combustion is that it has
less-wetted area compared to the "wedge" combustion chamber. Iron
heads are better than aluminum if they are run "hotter". etc. etc.
It is just a very complicated subject, with interlocking variable,
which lends itself to many "potential" improvements - but at a
"cost" - such as higher combustion temps using ceramics instead of
metal, and fuel additives (including H2) or water vapor, or the
high voltage Zenion possibility.
The main point of the posting was intended to be this
generalization: Hydrogen is **very mobile** and advantageous for
combustion - all else being equal. H2 has a "flame speed" which is
at least 10 time faster than gasoline. If you substitute hydrogen
for a portion of your carbon fuel, then the added efficiency (even
after the H2 has been reformed) can come "free" just from
utilizing only the unburned fuel. Getting there, however, is not
simple. There are MANY rip-offs going on now, under the broad
subject heading of on-board hydrogen generation. Caveat emptor.
It is as simple as that, in principle, although the details are
very complicated and this is the perfect area for (normally
dreaded) government intervention.
As far as what is apparent in the literature, there is no good
reason (other than added capital cost) why every hybrid should not
also carry water, and the added equipment to utilize steam for
onboard reforming of gasoline, to provide hydrogen for added
efficiency and lower CO2. This could take the Prius, for instance
from 60 MPG to 90 MPG. You do not need to store hydrogen - only
water.
But this adds yet another layer of complication and expense - like
an added tank for the water, and reactor fro reforming, and would
require demineralized water - so it is far from simple ... and
would probably need to be legislated-in.
Toyota is reluctant to even add the owner-option of adding more
batteries. That is comparatively simple. Go figure. The companies
will go only so far on their own initiative - after that - perhaps
this becomes the role of government to step in and legislate.
Jones
