RE: GAS-L: Internal Combustion with Producer Gas

[Prof P P Parikh <parikh@me.iitb.ernet.in>]

This is true. We can go upto 12 compression ratio. Generally a diesel
engine is converted to Spark Ignition Producer Gas Engine [SIPGE] and
experience shows that 11.5 - 12.5 is the range in which it can work with
non-knocking operation, lower range pertains to higher diameter and/or
high turbulence engines whereas higher diameter and low turbulence engine
better use lower ranger of compression ratio. If the base diesel has been
designed with about 50% excess air the power realisation is FULL and the
efficiency also is in the range of 25-28%. These figures are based upon an
actual experience.
Mrs Parikh
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Prof. (Mrs.) P.P.Parikh          Phone  Office : 5723496, 5767548 
Dept. of Mechanical Engg.                        5722545 Ext. 7548 / 8385 
I.I.T. Bombay				Home   : 5704646 	
Mumbai 400 076 INDIA		 Fax	Office : 5723496, 5723480
		
                    email : parikh@me.iitb.ernet.in    			   
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

On Tue, 25 Apr 2000, Mike Norris wrote:

> If as you say the knock limit of producer gas is 150, then one could
> increase the compression
> ratio by reducing the volume of the combustion chamber at
> top-dead-center.  The increased compression ratio will give the engine
> higher power and efficiency.  The compression ratio can be increased by 
> using a thinner head gasket or milling down the head.  Alternatively,
> one could also bolt metal pieces to the head or piston crown to take up
> volume in the combustion chamber, but the aerodynamics of modern engines
> are carefully designed.  Changing the flow could have a very negative
> effect on the combustion process leading to high emissions, rough
> running at low speeds and limited power at high speeds. You also have to
> be careful that the exhaust and intake valves don't crash into the
> piston.    This can be done by rotating the engine by hand through 2
> revolutions.  
> 
> Mike Norris
> DEKA Research and Development Corp.
> 
> PS. The increased efficiency of the diesel engine compared to the
> spark-ignition engine is due to primarily to the higher compression
> ratio.  The reduced pumping loss has an important, but smaller effect on
> the engine efficiency.
> 
> 
> 
> > -----Original Message-----
> > From:	Reedtb2@cs.com [SMTP:Reedtb2@cs.com]
> > Sent:	Monday, April 24, 2000 10:38 PM
> > To:	gasification@crest.org
> > Subject:	GAS-L: Internal Combustion with Producer Gas
> > 
> > Dear Andrew et al:
> > 
> > I have been collecting the plusses and minuses of having relatively
> > low 
> > energy producer gas.  
> > 
> > The energy content of producer gas is typically 4.5-5.5 MJ/nm3,
> > considerably 
> > less than the 94.01 gross (86.49 net) mJ/nm3 for propane; 37.69 (33.9)
> > for 
> > methane; 12 for CO; or 12.11 (10.2) MJ/nm3 for H2.  This is due to the
> > 
> > typical 50% dilution by N2 and 15% by CO2 and H2O.  
> > 
> > Therefore it is idfficult to store or pipeline producer gas.  On the
> > other 
> > hand it is relatively easy to produce where it is needed compared to
> > propane 
> > or methane!
> > 
> > During WWII the emergency retrofitting of gasoline engines resulted
> > therefore 
> > in a derating of 35-50% from that on gasoline, a big penalty for
> > existng 
> > engines initially chosen for gaoline.  
> > 
> > There are a number of cures for this problem.  One plus of producer
> > gas is 
> > that the octane rating is well in excess of 150, so (using the Tom
> > Reed 
> > octane rule:  octane no. ~ 10 X maximum compression ratio without
> > knocking) 
> > one can gain the derating back by increasing the CR of the engine,
> > using a 
> > turbo supercharger or just using a bigger engine.  Another problem is
> > that 
> > the intake manifold must be sized to the larger quantity of gas flow.
> > 
> > 
> > Modern cars tend to have lots of excess power (unless you live in the 
> > mountains).  In all other applications, choose an engine of adequate 
> > capacity.  
> > 
> > Yours truly,                        TOM REED
> > CPC/BEF
> > 
> > In a message dated 4/19/00 4:25:11 PM Mountain Daylight Time, 
> > andrew.heggie@dtn.ntl.com writes:
> > 
> > << 
> >  >Basically -- I was going to prove by math modeling why it is
> > hopeless to
> >  >get maximum power from an internal combustion engine using producer
> > gas in
> >  >a manner that all would grasp -- to the entire list.
> >   >>
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