05/09/2004

Water and stoichimetry


Water is exactly stoichiometric.  If and only if, the charge is exactly
stoichiometric will the effect be exactly neutral or stoichiometric.

If the mixture is either rich or lean, the addition of water will drive
the end result closer to stoichiometric.  The more water, the closer to
stoic it gets.  

Remember that stoichiometry is determined by the total amount of the
fuel as related to the total amount of oxygen.  Adding a balance mixture
to the original mixture will drive it closer to a balanced mixture.

Adding alcohol for example, will always richen the mixture.  The oxygen
within is insufficient to fully oxidize the fuel, leaving an excess fuel
residual.  Add enough and the engine runs pig rich and boggs and barfs.

Same with virtually every chemical added to or used as fuel.  If there
is not enough oxygen contained within the fuel molecule to fully oxidize
all the fuel atoms ( which virtually all fuel molecules are like ),
addition of this fuel molecule will eventually drive the mixture pig
rich.

Furthermore, the combustion of water returns close to the energy it took
to decompose it in the first place, so again unlike excess fuel, it does
not eventually choke the combustion off.