Ken,
The paper from India states that there is some de-rating for producer
gas compared to diesel with their engine. They didn't see the same sweet
spot for spark advance theorizing a need for retarding spark because of
high hydrogen flame speed. Different engine, different PG? In their
case NOxide emissions increase 2 to 10 fold with increased spark
advance. Is this a concern with Mr.Lister? After CR, what accounts for
all the extra power with your test rig?
Thanks,
Alex
On 14/10/2012 4:26 AM, Ken Boak wrote:
Hi Peter, List
Just for explanation, the Lister conversion project took place over
three consecutive Workshops at All Power Labs, Berkeley, California.
Between Feb 2010 and April 2012, the team slowly picked away at the
project.
The original spark ignition circuit was based on an Arduino, with a
Hall effect sensor being triggered by a tiny neodynium magnet taped to
the flywheel rim. A darlington transistor drove the low tension side
of a car ignition coil.
https://files.pbworks.com/download/Mk7b7ymPda/gekgasifier/30638003/Lister_spark.pdf
I used a variable resistor on one of the analogue input pins as a
"timing control". The idea was to fit the magnet very well in advance
of the optimum position, and then adjust the timingcontrol to add a
given delay, to allow the firing point to be adjusted to the position
that gave the best running.
This is what we used in the February 2010 workshop, when the engine
first ran on woodgas. However a later discovered bug in my code meant
that the timing control was not really working as intended.
For the Fall workshop of 2010, I remade the ignition circuit on
stripboard and shipped it out to California, and Ron Ohler, Mike La
Rosa, Marcus Hardwick worked on the project. I could not attend that
workshop.
The team fitted the newly positioned spark plug in the side port and
proved that the engine would run.
Marcus and I revisited the Lister project in March 2012 in the run up
to the April workshop. The Lister was converted back to stock 17:1
compression ratio and given a new head gasket and more permanent
arrangement with gasifier, cooling and exhaust systems.
The electronic ignition (my department) was our Achilles heel this
year, and after a couple of microcontroller and transistor burn-outs,
we eventually replaced it with a commercial MSD spark ignition unit
and coil. Ron Ohler and Andy Schofield went on to get the engine
running sweetly, after a lot of fiddling looking for the best ignition
point.
I have now returned to the UK, and I am keen to maintain interest
going in the spark conversion of diesel engines. The developing
countries are littered with small hp diesels such as Lister, Petter,
Changfa clones performing pumping, generation and agricultural
processing tasks. To come up with a cost effective spark conversion
for these generic engines so that they can be economically run on
producer gas from biomass, would be a major step towards petroleum
independence.
The original IISc paper describing the performance testing of a 3
cylinder spark converted Indian diesel engine at 17:1 CR is here:
http://cgpl.iisc.ernet.in/site/Portals/0/Publications/ReferedJournal/Biomass%20derived%20producer%20gas%20as%20a%20reciprocating.pdf
regards
Ken Boak
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