[Gasification] water injection of producer gas fired ic engines

[jim mason]

i don't remember seeing any disucssion here on water/steam injection
into an ic motor running on wood gas.  so far in the books i've not
come across it either, but it is likely there, as i've yet to finish
all the books.  anyways, water injection would seem to help much with
several liabilities of woodgas fired ic engines.

contrary to our usual first guess, water injection in gasoline or
diesel motors is helpful more for its effects on combustion, than for
its waste heat to expanding steam scavenging effect.  the later is
helpful, but it seems the former is the bigger assist.

water/steam injected into a combustion environment is reasonably
explained here: http://www.eng-tips.com/faqs.cfm?fid=811.  the claim
is that water slows the oxidation of hydrogen (which is very fast),
and helps finish/speed the combustion of CO to CO2.   the water gas
reaction is CO + H2O = CO2 + H2.  the result is completely oxidized
carbon, and H2 which oxidizes quickly on its own.  the result is
claimed to be a more uniform combustion rate / flame front, with a
more complete total combustion to CO2.

this would seem to have a couple very important effects on a producer gas motor.

1.  the relatively high emission of unburned CO is producer gas fired
ic motors (10-20% i think) would be reduced, with a related increase
in power.

2. the notorisously slow flame front of producer gas would be
generally increased as the CO would complete its combusion faster.
higher rpms would be possible.  but also for the same reason, the
engine would be limited to lower compression ratios.

for a slow speed genset, all this is likley not helpful, as the slow
rpm tends to give enough time for full combustion to happen.  for a
mobile application where momentary higher power is needed, this seems
very important and potentially very helpful.

water injection is pretty simple.  fumigate the intake with a mister.
adjust a small valve as needed.

has anyone tried this?  is there data on this anywhere in the
literature?  it seems too obvious to not have been well explored
already.

j