fangle
---------------------
16 Jul 1998 20:18:45 -0700
"Robert Harris" 
Subject: Bi Fuel.

The difference between "Dual Fuel" and "Bi-Fuel" is simple. Dual fuel is one
or the other but no both at the same time, where as Bi Fuel means one or
both at the same time.

The most common example of Bi-Fuel is when methanol is injected as the boost
goes positive on a turbo engine.  Speaking of which - does anyone know where
I can find some reasonable text and theory about eductors - have a couple of
fangles I'm twirling about in my head.  Looking at a reference about Sendyka
pressure wave supercharging - a vague reference and drawing of an early
patent.

But, someone has brought up an idea near and dear to my heart - cheap fuel.
To make the history short, I am considering using a propane "hat" carb
simultaneously with the soon to be fuel injection on my RV.  I would set the
carb such that it would be very lean 21 to 1 or more off idle and simply let
the lambda sensor trim it to stoich with gasoline.  Vary the pressure to the
carb and vary the mixture thus somewhat controlling the consumption rate.
Thus, when "excess" or "cheap" propane is available, I would simply switch
the propane on and burn it with the gasoline.  Also, if the load became
heavy - I.E. up hills, simply switching on the propane would significantly
raise the octane of the fuel.  Butane is approaching 100 octane, Propane
112 - the gaseous mix would have an octane of the blend of the two.

Another simple modification would be to use a nitrous oxide valve (designed
to live at 1000+psi - far more than adequate for the ~250 psi max for
propane) plumbed to the liquid outlet of the propane tank.  Then, under
load, simply open the valve and let a jet of liquid propane enter the plenum
of the intake.  It boils at -44F, the flow thru the fixed jet depends on the
pressure, the pressure depends on outside temp, so when its hot - more
pressure, more flow, more supercooling and a higher blend (gasoline/propane)
octane. The EFI lambda (Standard EGO) would correct the mixture back to
stoic.

The only problem is that LPG is no longer cheap.  Then this someone brought
up the fact that depending on where and when, diesel fuel can be
significantly cheaper.  Then, in our usual manner, we both proceed to stage
the first, complicating defecation.  Thimking about spark advance, modifying
curves etc.  This could be fun - but so needless.

The simple fact is that diesel would only work as a cruise extender.  Would
not want to burn it at idle, or under medium load up.  Since its only going
to be used in a narrow power region, it would not be to complex or high
fangled.  And it would not need to operate at idle, warm-up, heavy power or
other things - just at cruise.  Might even use the turn on of cruise control
to turn the system on - neener neener.

Thimk simple electrical pump (on/off) fuel pressure regulator with bypass,
two solenoid valves and two fixed jets (1x 2x relationship) and we have 4
levels of flow ( 0 - 1 - 2 - 3 on - two bit logic ).  A dollap of logic and
we be styling.  The logic simply needs to know when to turn the cruise
extend fuel on.  Simple throttle position and rpm logic might be all that's
needed. Simply put, supply a nice chunk of diesel fuel with fine control
remaining with the gasoline and lambda (Standard EGO) - automatically
trimming it in. At a certain throttle position or MAP, simply kill the
diesel.

Yes - we know that the octane sucks - but WTF - the purpose is to cruise
burn cheap fuel not to make ultimate power.  Part of the problem with diesel
is that it is a long chain molecule.  From my recent readings in combustion,
this means that the molecule may not be completely broken down in normal
spark ignition combustion.  So even if we were chemically correct at the
EGO, much of the burn would be late and lean and the remaining would take
place in the exhaust.

First fangle - preheat the damned fuel through a hot water heat exchanger so
that it enters the manifold at least near the boiling point of water.
Remember that knock ain't the problem, burning it is.  Hot diesel will break
down in a thin gasoline flame much easier than cold diesel. If it can be
burned faster, it will generate more useful heat and less late lean burn
heat.

Next fangle - simple water injection.  Simplest step is to simply replicate
the diesel setup to meter water into the manifold.  Step the water with the
diesel and we shouldn't have to worry about knock - specially since as we
come out of "cruise" and transition into power, we are going to drop the
diesel fuel.  This can be independent of any other water injection system,
or included within it.

Last fangle - emulsify the diesel with "water" and an emulsification agent.
What that does is when the water emulsified within the blobule of fuel
"explodes" it shatters the long string of diesel molecules and turns them
into a fine cloud of individual molecules. Acetone is my first candidate,
but I am looking for something cheaper to use to carry the water into the
diesel. This emulsification would have higher octane, faster burn and may
not need much fangling as a cruise fuel.

Reprint of an earlier post

Reference - gasoline faq part 4

http://www.cs.uu.nl/wais/html/na-dir/autos/gasoline-faq/.html


Combustion  -  third edition   by  Irvin Glassman  Princeton University

Chapter 8   C. Formation and Reduction of Nitrogen Oxides
section 4. The reduction of Nox  (pg 378)

"The problem of NOx reduction is more difficult in heterogeneous systems
such as those which arise from direct liquid fuel injection and which are
known to burn as diffusion flames. One possible means is to decrease the
average droplet size formed from injection. Kesten [32] and
Bracco [33] have  shown that the amount of NO formed from droplet diffusion
flames can be related to the droplet size, viz., one large droplet will give
more NO than can be obtained from a group of smaller droplets whose mass is
equal to the larger droplet.  Any means of decreasing the heterogeneity of a
flame system will decrease the NO.  Another possible **** practical ****
emphasis is mine not the authors) scheme is to emulsify the fuel with a
higher vapor  pressure, non soluable  component such as water. It has been
show [34] that droplets from such emulsified fuels explode after combustion
has been  initiated.  These microexplosions occur when the superheated water
within the fuel droplet vaporizes, hence appreciably decreasing the
heterogeneity  of the system.  A further benefit is obtained not only

<<<>>>


available for dilution, but also because the water is present in the
immediate vicinity of the diffusion flame"

In other parts of the book, it describes how water is formed and reduced so
many times in the combustion process it makes my head "swim" and that a
modest amount of water may help combustion - particularly in the conversion
of CO to CO2 - but that's another fangle.

[32]  Kesten, A.S. Combustion Sci Tech 6,115 (1972)
[33]  Bracco, F.V. Int. Symp. Combustion, 14th, p. 831, Combustion Inst,
Pittsburg Pa (1973)
[34]  Dryer, F.L. Mech Aerosp. Rep. no 1224, Princeton  University,
Princeton  NJ (1975)


These subject has been around for a long while with lots of misconceptions
etc.  Glasman implies that it is a known practice in combustion engineering.
Gunnerman - of the emulsified fuels fame with caterpillar uses a secret
emulsifying agent to get has blend of water and fuel.  Numerous attempts
have been made on various news and mailing lists using detergents to
"emulsify" the solution with not real good results.

My reading of the above, in context with a lot of other things, is all the
water is supposed to do is shatter the bloblet into very fine droplets and
let the flame do its thing.  Various discussions I have lurked either assume
the water forms a structure for enhanced burning or use the emulsification
to carry large amounts of water to replace fuel - to get more mileage or
whatever Mr. Gunnerman.

What I am considering is using a modest amount of water to do exactly as
Glassman reports - shatter the bloblets and I have identified a potential
"secret" emulsifier - Acetone - dimethyl ketone - CH3COCH3 - as my best
candidate.

Acetone is highly soluble in alcohol and petroleum products.  It also is
infinitely soluble with water making it highly miscible.  Furthermore the
double bounded oxygen in the central CO actually forms a "weak" electron
bond to a hydrogen atom in the water molecule.  One mole of acetone will
"bond" with one mole of water and carry it into solution with petrol.

About acetone - it is normally blended from 5 to 10 percent with either
alcohol or nitromethane and petroleum to eliminate phase separation caused
by water in the fuel.  Its octane is about the same as methanol.  It has a
lower boiling point, similar latent heat of evaporation as
methanol, higher autoignition temp, far higher ignition energy required, and
less corrosive
than methanol.  Since the EPA squashed toluene, its becoming the Home Despot
paint solvent of choice and the price is falling.  Its heat energy is above
ethanol and its density is on the heavy side of the gasoline range.

As soon as I get the gas gauge working on the second fuel tank on the Al
Bundymobile Dodge Peeek Up, I'm going to try it.





fangle
---------------------
17 Jul 1998 00:55:30 -0700
"Robert Harris" 
Subject: RE: Bi Fuel.

> 17 Jul 1998 01:23:00 -0500
> dave.williams@chaos.lrk.ar.us (Dave Williams)
> Subject: Bi Fuel.
>
Deleted stuff

>  [aside to the fanglers - Robert and I have discussed this by email.
> Fuel/water emulsions have been around a long time and are used in some
> industrial applications with excellent results, though a few
> entrepreneur types have "discovered" the process and applied it to cars
> from time to time, with absurd claims.  Basically you force the fuel and
> water through a microscopic aperture(s) under high pressure.  This
> leaves a milky-looking goo, much like what comes out of your crankcase
> when you have water in the oil.  The droplet size is small enough the
> mix can stay emulsified for hours; eventually it'll separate back out to
> water and fuel.]
>
>  How are you going to make the emulsion in a motor vehicle?  Stationary
> plants use big pumps.  Something like a 12V pressure washer might work
> as a pressure source - has anyone seen a 12V pressure washer?
>

Of course, some of us live in parts of the country where Pick Yur Parts
actually has Intact VW Rabbit Diesels.  Thimk teeing two input lines - one
water, one cruisocrap extender with some "lube" in it.  Teeing them together
at the inlet to the diesel pump.  Instead of a breakover valve, a fine mesh
"emulsifier" that blows the combined stuff into the manifold at over 1200
PSI. Think that would mechanically emulsify the stuff?  Varying the
"throttle" position on the diesel pump would vary the amount of stuff pumped
into the manifold as a percentage. Engine rpm takes care of the rest. An A/C
clutch could turn it on or off.

Then, of course, you can accomplish chemically a similar thing - like
blending the cruisocrap with acetone and water and simply pump it in.  Only
problem is until I find another solvent as good as acetone at taking water
into solution with petroleum, its too expensive to waste on cruisocrap.