Re: GAS-L: Internal Combustion with Producer Gas

[Peter Singfield <snkm@btl.net>]

At 08:06 PM 5/1/00 -0700, you wrote:
>
>
>Peter Singfield wrote:
>
>> OK -- if producer gas works fine in a regular diesel using fuel injection
>> ignition -- why can't is work at those same compression ratios using spark
>> ignition??
>
>    The actual fuel burned in the engine shouldn't matter, as long as the
>internal parts can handle the stress and everything is set up to avoid pre
>ignition.  Pilot diesel injection is an effective strategy because it
requires
>little, if any, modifications to the engine itself.  The diesel injectors
run in
>"idle" continuously and the externally mixed gas takes up the rest of the
load.

Obviously there is an ignition problem with just "spark". The diesel
principle is injection of a fuel into an atmosphere heated to the flash
point of that fuel with enough oxygen present to accomplish combustion.

Some gasses -- such as ethel ether -- ignite at lower temperatures -- ergo
-- ether is used for cold starting diesels.

Other gasses require to high a temperature to ignite??? Why will producer
gas not ignite in that highly heated environment?

As it stands now -- the little bit of diesel fuel injected into that
heated, compressed, mixture of producer gas with air -- does ignite and
that "flame" ignites the entire charge of air and producer gas.

My suggestion is to ignite a part of compressed producer gas air charge in
a spark plug "chamber" and then the flame from that would ignite the main
chamber mixture -- closely approximating what diesel injection does in that
same circumstance. This would allow running at standard diesel compression
ratios.

Since diesel engines are relatively low RPM compared to high performance
gasoline engines -- there is no problem in the delayed firing due to flame
ignition verses direct spark ignition. And simply adjusting timing will
properly compensate.

Mind you -- there is one more factor -- it is called detonation. Better
known as "knocking". The small amount of diesel fuel being injected may
well be required to control detonation. If so -- water injection (much
cheaper than diesel fuel) might well achieve the same results.

>
>    Some hydrogen conversions I've read about use modified spark plugs
installed
>where the diesel glow plugs are normally found.  In this manner, little
>machining, if any, is necessary, and again, the fuel is mixed outside the
>cylinder.

what do you do when there are no glow plugs?? The injector is easily
replaced with a spark ignition device.

>
>    I think direct injection is a better strategy because it avoids
throttling
>losses, backfire and a host of other woes.  (With producer gas as the
fuel, high
>pressures would be necessary to get sufficient power.  This is certainly
>possible, but I wonder if it's really viable.  The big engine makers like
>Caterpillar still rely on external mixing for natural gas.) 

Good points. I believe that one has to live with the throttling losses in
this case. I can see methods to inject producer gas at 2000 PSI plus -- but
it become a very expensive modification. 


 Roy McAlister of the
>American Hydrogen Association advocates a "spark ignitor/injector" that
serves to
>deliver fuel to the cylinder AND fire it off with a spark.  In this way, any
>engine can be easily modified for direct injection.  I've been waiting for
many
>years for his prototype to become a reality, yet no product appears
imminent as I
>write this.

Pure hydrogen is far richer than producer gas with all that nitrogen.


>> It would be easy to machine a spark plug adapter that would fit into the
>> injection fitting port -- that would increase volume as much as one
>> required as well as being a precombustion chamber.
>
>    Direct injecting a gaseous fuel creates a "variable compression ratio"
>engine.  The compression ratio would fluctuate according to demand, and if
>controlled by a microprocessor with an appropriate fuel map, could produce
more
>power than an externally mixed gasoline engine of equal displacement.

Probably true.
>
>    I would love to see an engine operating with such a direct injection
>strategy, coupled with variable valve timing and intercooled turbo
charging!  In
>your words, Peter, we'd be moving out of the flathead age, for sure!  (Ok,
if I'm
>going to dream, I'd want a cross flow hemi head too. . .)
>
>> And not other changes need be made to that engine -- except clipping a
>> magnetic transducer at the right place on the pulley riding the front of
>> the crankshaft.
>
>    Four stroke engines only take in fuel on every other crankshaft
>rotation--that's why cam sprockets are twice the size of crank sprockets.
I'm
>sure you know this.  One strategy that may work for popular engines (like the
>small block Chevrolet) is a belt driven distributor that bolts onto the front
>part of the timing cover.  These are manufactured for racing engines, but
can be
>adapted to serve as timing devices for direct injection.
>

No -- the programming would ignore the non compression pulse. The trigger
transducer would give top dead center of the first cylinder. RPM is a given
(the computer counts and gets the exact RPM) and the firing order is
calculated -- with advance -- accordingly. One need a pressure transducer
built into that first cylinder  spark plug device -- to tell the computer
which is the "beginning" power stroke. On the other hand -- a simple limit
switch on an exhaust valve (or intake) would do the same. This could be a
simple, solid state, proximity switch. Many ways to skin that cat -- but
under computer control -- you only need that one indexing point -- plus a
yes/no.

But your also right -- it probably would be quicker to adapt a distributer
to the cam.


>> You could then plug the timing into your PC and move it around as one
>> wanted -- by simply clicking the keyboard.
>
>    Companies like Eco Fuels in Langley, B.C. are working on fuel maps for
>various computerized engine applications.  I've heard discussion that some of
>these may be effective for the type of thing you are proposing here.

Take a look at this Url:

http://www.rodi.com/Products/Engine/engine.html

This should be very enlightening regarding complete computer control of a
diesel -- just as one example.


>
>>  imagine spark advance -- or timing -- is part of the formula as well.
>
>    Modern turbo diesels utilize engine speed, air density, turbo boost and
>throttle position as variables in their fuel maps.  Torque and horsepower
can be
>altered with a laptop computer.  I've seen the system for Cummins N14 engines
>(these displace about 10 liters), and it's very impressive!
>
>> So -- why doesn't some one do this? Looks so easy to me.
>
>    I think it can be done.  Where is the market for producer gas engines?
>

Right now -- not so great. But it is that old -- which come first -- the
chicken or the egg?

There are so many diesel engines out there of all sizes. A simple diesel
engine conversion kit for spark ignition using producer gas would
definitely open much more interest in this area.

The ideal producer gas engine is one that does the job well and does not
require any diesel fuel.

If one bought a new diesel -- with out the injection system -- the saving
in costs should more than pay for the spark ignition device.

The real question is can a diesel be converted in such a manner?? That is
without having to reduce it's compression ratios -- be that purely due to
piston/combustion chamber configuration -- or due to super/turbo charging.

Remember -- the "charged" diesel has a lower compression ration in
consideration of the forced loading. In the end -- it is the pressure --
not so much the compression ration -- that is important in modern, high
efficiency, diesels.

As it stands now -- we are told this must be reduced in order to operate
using producer gas.

This is a major "mechanical" adaptation. I simple wonder why compression
must be lowered when running producer gas only -- when it does not need to
be when running a small amount of diesel??

Pre-ignition in a small "squeeze" chamber -- built into an adaptor that
retrofits right into the same place the standard diesel injector fits --
would seem to be a viable direction of investigation.

Hooking up a spark ignition system -- be it totally computerized -- or by
simply fitting a distributer to the cam -- is not a problem.

Finding the ideal method to ignite the compressed producer gas appears to
be a problem -- why else the reduction in compression ratios?

That is the question here??

If I was still in Canada -- I would be picking up a scrap Cummins truck
diesel for next to nothing and doing some quick experimenting. An old 220
Cummins -- as example. Or even an old 185 HP Mack diesel. Nobody runs these
engines anymore. So even in still good running condition -- they are very
cheap. And so many were made!


Peter Singfield
COROGEN
Executive Director
Xaibe Village
Corozal District
Belize, Central America
Tel 501-4-35213
E-mail: snkm@btl.net


>robert luis rabello
>
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