Hi Robert,
Thanks for your reply and comments. While I agree with a lot
of what you have said I see we are at variance with some points as I dont
think you have fully understood what I said or Covey was saying.
----- Original Message -----
From: robert luis rabello <[EMAIL PROTECTED]>
To: <biofuel@yahoogroups.com>
Sent: Saturday, May 05, 2001 5:21 PM
Subject: Re: [biofuel] Vapour Carburetion
>
>
> David Reid wrote:
>
> >
> > He maintained while one cannot increase the number of BTUs in a
> > gallon of gasoline one can extract more of the available BTUs with an
> > efficient vaporizer.
> I've driven "vapor carburetor" vehicles for years, and this claim is
simply
> nonsense! A lot of engineering experience goes into designing engines
with
> sufficient "swirl and tumble", fuel atomization and precise control of the
air
> fuel mix for optimal combustion. If you want a more efficient burn,
increasing
> compression pressure, reducing friction, controlling intake and exhaust
> conditions and ridding the engine of throttling losses will all make a
> difference--but not in the realm frequently claimed by the "vapor carb"
> enthusiasts.
>
**Here he was not talking about and using a conventional carburetor in the
conventional manner as this is not used in the normal sense (ie petrol is no
longer entering the float bowl, being metered through jets, and sprayed into
the airstream entering the intake manifold). The only part the conventional
carburetor played in this role was when it was switched back to this role
for starting the engine and bringing it up to temperature for the first 5 to
7 minutes at which point it was switched either manually using an accurate
temperature probe and digital dash readout or automatically again using an
accurate temperature probe and auto controls. In this mode the only role the
conventional carburetor played was as a conduit for the already premixed
vapourised fuel that only needed to enter the cylinder, be compressed,
detonated, and combusted. In this role the amount of already vaporized fuel
required for the same output is far less Nothing is being wasted and all
fuel is being combusted. With virtually no fuel being consumed in raising
the fuel from ambient to detonation point the fuel requirement is therefore
far less.
>
> > Then at a constant 60 mph you
> > could travel 48.23 x 60 miles or 2,894 miles to a gallon of gas if
there
> > were no losses thermally or to friction.
> Something is terribly wrong with the math and science, here. . . If
there
> were no thermal or friction losses, the vehicle would continue moving
forever,
> or until some OTHER force acted upon it.
** Here I think you missed the point again. He was talking theoretically and
calculated the maximum distance the vehicle would travel using a gallon of
gas if nothing acted upon it or impeded it. Both you and I know this is
imposssible but to demonstrate a point there is no reason it should not be
worked out or used in the arguement.
>
> >
> > He then went on to compare locomotives to automobiles and demonstrate
how
> > much more efficient they are in terms of moving mass and acceleration
> > efficiency which is entirely true.
>
> Comparing a machine that runs on the road to one that runs on rails is
> analogous to comparing a bird with a sea slug! Further, modern
locomotives
> utilize a diesel electric power plant, wherein the engine is running at a
fairly
> constant rpm and can be "tuned" for optimal performance. The electric
motors
> actually propel the machine down the track.
>
** Probably didnt explain this very well and dont really want to go into it
as I could get caught up for hours on a separate side issue. In the context
of the discussion it was highly relevant in that a diesel locomotive gets
something like 918 mpg per ton in comparison to the large automobile that
will get from 8 to 20 mpg which is 4 to 10 per ton or less. Using a fairly
typical example of a 1500 hp train on a level route with one hp per ton of
load he demonstrated the theoretical acceleration from 0 to 60 mph with hp
equaling 17.8 lbs of accelerating force applied to a ton of mass would be
0.0089th of a "g" of acceleration. He used this to demonstrate how
inefficient cars are and pointed out that for a car to equal this that a 351
CID enngine (in a 4500 lb vehicle) would have to accelerate from 0 to 60 in
just 4.9 seconds. For a 2 ton car to have the same efficiency as the train
it would need to have a 2 hp motor (this is for both acceleration and
cruising) and do something like 459 mpg per gallon.
While it may not be an entirely fair comparison and your not comparing
apples with apples it certainly gets the message across that cars are
inefficient and someone some where spent a lot of time designing the train.
By the way he also pointed out that the diesel train engine was still only
25% thermally efficient. Says alot about cars dosnt it?
O.T. I am reminded of George Washington Carver saying "If God had intended
us to smoke he would have turned our nostrils up". Totally irelevant of
course but somehow totally connected for some reason. Maybe I just like
laughing at the stupidity of man occassionaly.
> >
> > Most of the heat energy generated in an internal combustion engine (or
ICE
> > as I finally learnt the other day) is wasted in raising the temperature
of
> > the unexploded portion of the charge in the cylinder to the point where
it
> > also can be detonated and exploded with a fair proportion of the total
> > disappearing through the exhaust valve, exhaust manifold, and out the
> > exhaust.
>
> <snip thermodynamic nonsense>
** Are you sure?
>
> Most of the usable heat energy available to an internal combustion
engine is
> expended in driving the piston down the first 1 / 3 of its stroke.
Calculate
> the difference between the heat at maximum compression and the exhaust
> temperature when the valve opens, and you will determine the delta - T of
the
> engine. ( A long time ago, a Frenchman named Carnot worked through math
> considerably more complex than this to arrive at the conclusion that heat
> engines cannot EVER be more than about 60% efficient, with an infinite
heat
> sink!) The nature of the ICE determines its ultimate fuel efficiency, and
if
> the "vapor carb" myths were true, those of us who burn propane and natural
gas
> in our vehicles would be getting substantially better fuel economy.
** As I said there is a reasonable amount of the energy used in raising the
temperature to detonation point. Believe compression ratio as quite a
bearing here.Will admit I am a little out of my depth on this point as I
have seen arguements advanced both ways here and still dont know what the
entire truth is here.>
> Truthfully, an externally mixed gaseous fuel will displace some of the
> intake air and result in LOWER power and fuel economy levels. The only
way
> around this, is to squeeze the fuel harder (which is easier to do with a
gas),
> or inject it directly into the cylinders AFTER the intake valve has
closed.
** Believe you are probably right on this point but then again not a lot of
energy is being wasted in raising the ambient temp to detonation point.
>
> While you rightfully post that a considerable amount of heat is lost
through
> the exhaust, it's at a temperature that, for the engine, is essentially
useless
> for anything other turbo charging, turbo compounding or a bottoming cycle
with a
> different working fluid. Either that, or you could use this heat to
"reform"
> your fuel with steam, then directly inject the resulting gas into the
engine.
> This is an approach I would love to try, if I had a little money!
** In this case it is being used to heat and vaporize the incoming air/fuel
mix with no loss of energy or power to the vehicle. What energy the engine
can get out of the gasoline it has already done but by cycling the exhaust
gas through the vaporizer before it enters the the exhaust it manages to
utilize the latent energy it contains.>
> <more snippage>
>
> > Vaporization ensures thorough mixing and incorporation of the gasoline
> > droplets before they enter the cylinder thus ensuring minimum wastage
and
> > complete combustion, unlike injection where the atomized droplets have
to be
> > broken down even further before they can be combusted.
>
> You are mistaken here. Modern, high pressure fuel injection results
in VERY
> complete combustion. The computer controlled feedback systems, coupled
with
> catalytic converters (I'm no friend of exhaust catalysts, but they are a
> necessary evil with current technology) produce significantly cleaner
burning
> engines than any vapor carb can touch. That's one of the reasons why the
once
> thriving market for propane and natural gas conversions in British
Columbia
> (where I live) has almost completely died. I have the provincial
emissions
> control test slips to back up my contention in this regard.
** You could be dead right and probably are here in relation to complete
combustion but again a certain anount of energy is required to raise the
incoming air and fuel from ambient temperature to detonation point. Again
the same with propane and natural gas so there is no way you can compare a
vaporization system that raises the temperature of a gasoline/air mix prior
to entry to the cylinder with these.The only fair comparison is results
produced. Also note that for catalytic converters to work (most are based
on Platinum and this is where most of the worlds supply is disappearing)
there has to be incomplete combustion initially otherwise they wouldnt be
fitted.
>
>
> > 200 mpg carburettors may not be realistic
> > or achievable but we can still make a lot of improvements. Some of the
> > problem is that people refuse to think outside the square and accept
just
> > about all they are told.
> > B.r., David
> >
>
> Well stated! Let's look at variable compression ratios, rotary
valves,
> ceramic parts, fuel reforming and direct injection for engines fueled on
> renewable energy. Let's reduce the mass of our vehicles and move to
hybrid
> electric drive trains. These would be good places to start.
** The Honda Insight and Toyota Prius are one of the steps in the right
direction. Hopefully there are a lot more improvements to come in the not
too distant future.
B.r., David
>
> robert luis rabello
>
>
> Biofuel at Journey to Forever:
> http://journeytoforever.org/biofuel.html
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