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<DIV><FONT face=Arial size=2><STRONG>Hi Tom and
Colleagues,</STRONG></FONT></DIV>
<DIV><FONT face=Arial size=2><STRONG></STRONG></FONT> </DIV>
<DIV><FONT face=Arial size=2><STRONG>Tom as you are clearly the authority on
what you say:</STRONG></DIV>
<DIV><BR>Simple thermodynamics predicts and practice shows that both power and
efficiency increase linearly with CR. Since producer gas has an octane
over 180, various groups have been "souping up " gas engines, using CR in excess
of 18/1. Little old producer gas has grown up.<BR><BR><STRONG>I would be
pleased to have explained from anyone with producer analysis gas experience, how
you can say that all producer gas is over 180 octane, or possibly "can" be over
180? It would be difficult to convince the engine expertise on whom I rely, to
accept that all producer gas has the same degree of anti-knock, given not all
gasifiers are equal. Based on 135 btu/ft3, the Caltex Oil Co. guy who
advised us regarding octane rating, "suggested" we stick to 120 as the maximum,
being a realistic figure. I think it important to clarify how variations of
producer gas octane can eventuate.</STRONG></DIV>
<DIV><STRONG></STRONG> </DIV>
<DIV><STRONG>This then leads to a second question, which personally creates
a black hole in how I have been forced to accept the reality, of working with
high compressions in diesels operating on dual fuel/producer gas. How can then,
the spontaneous ignition temperature be increased more than the "about"
600C found at 16:1 ratios, given that we also must consider the operating
temperatures? I can appreciate that you can tweak any engine performance
in a fixed load/conditions situation, but I doubt if combustion stability
at over 17:1 could be assured if the load/conditions fluctuate as for variable
power generation.</STRONG></DIV>
<DIV><STRONG></STRONG> </DIV>
<DIV><STRONG>In the Lister (NZ) workshops, we did many controlled trials with
their larger engines (16:1), but one sticks out, because it frightened us all
when it happened. We had finished a long full load test without the air filter
fitted, and when we dropped the load from the hot engine, I put the air filter
back on, which immediately began to wind the rpm up well over the 1,500 of
the diesel governor setting. It was a run-away situation on auto ignition,
because locking out the diesel had no effect. It was fixed by pulling off the
flexible gas connection. Clearly change of the gas/air mix affects this
spontaneous ignition temperature, and there would seem to be little value of
working with ratios over 16:1 unless it can be proved the economics or emissions
can be seriously advantaged. It does come down to $$$ in the
end(:-)</STRONG></DIV>
<DIV><STRONG></STRONG> </DIV>
<DIV><STRONG>Not sure if I can locate some of the peak pressure charts from that
time, but certainly Prof.John Stevenson of Auckland University's Mechanical
Engineering was involved, and used them in a Paper he presented on how he
thought dual fuelled diesels should be controlled.</STRONG></DIV>
<DIV><STRONG></STRONG> </DIV>
<DIV><STRONG>Enlightenment anyone please?</STRONG></DIV>
<DIV><STRONG></STRONG> </DIV>
<DIV><STRONG>Doug Williams.</STRONG></DIV>
<DIV><STRONG>Fluidyne.</STRONG></DIV>
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