05/08/2004

Glassman and Combustion

Glassman - "Combustion" 3rd Edition.

Basically lays out the all excess anything is simply excess anything and
adds nothing to the energy release of combustion.  Mass is Mass.

By the middle of WWII, Naca had verified that whether it was excess fuel
or whatever, it made little difference on the energy.

Thus one pound of fuel could be replaced by one pound water or
water/alchol or other substances.

But water always had a special place.  Engines could stand at least 160%
of the weight of fuel as water - but bogg out at 50% excess fuel.

By Glassman's time, we had the atoms is atoms theory well worked out.

Water, under combustion, generates free radicals starting heavily around
500 centistupid and has disappeared well before the 4800 F ( Non-Frog
Temperature ) that is about normal for gasoline.

Glassman discuss's temperatures and relates it to 5 factors.

1.  Chamber pressure - minimal at up to 50 atmospheres - in fact less
than 5%.

2.  Atomic weight of the charge

3.  Atomic ratio of the charge ( Carbon, Hydrogen, Oxygen, Nitrogen )

4.  Energy present and released by combustion.

5.  Energy loss's

The molecular history of each molecule and atom is meaningless.  Whether
the atom comes from veggi oils or from hydrazine is not relevant - only
the 5 factors.

Excess air or excess fuel or fluid IF THEY DO NOT CHANGE stoichiometry
are simply excess mass.  Thus fuel in excess of the available oxygen is
simply excess atomic mass.  Air in excess of the available fuel is
simply excess atomic mass.  Water is NOT.

Water is the stochemic result of the combustion of hydrogen and oxygen.
Adding water to the intake charge changes the stoichiometry of the
charge!!!

Parts is parts, atoms is atom, adding hydrogen and oxygen to the charge
without the accompanying nitrogen from air, will tend to raise the
temperature of combustion.  Lacking fuel energy will lower temperature
of combustion.  But it still burns.

Water entering the chamber changes combustion.  Water initially absorbs
heat and the water reactions are endothermic.  Later, the hydrogen and
oxygen released early burn into water.  Much of the energy needed to
separate the atoms is returned when they burn.

This cycle keeps the end gasses cooler longer than without excess water
and thus raises the knock limit.  Simply cooling the gasses by
intercooling would not have this effect.

And Glassman explains why ceramics do not raise peak temperature of
effect burning much near wot, but will make differences as the load
decreases.