Ethanol mogas

Mike Noel wrote:
I think alcohol is a polar-covalent solvent that tends to hold water in
solution with gasoline. I suspect instead of getting the alchohol out, you
would be suspending water in the fuel that you would not be able to drain.


That doesn't sound likely. Otherwise the popular method of alcohol
testing wouldn't work. You can test test the presence of alcohol in
gasoline by mixing gasoline with some water in a test tube, agitate the
tube, and check to see if the water level rises.

On the other hand, if you have an engine that can burn alcohol, perhaps some
amount of water in the alcohol could boost the performance of the engine ala
water injection in old military aircraft. You could turn some of that
wasted heat into steam before dumping it out the exhaust.

I never quite understood why injecting water into engine will increase
its performance. I have no doubt it's true that Boeing used to do that
on their jet engines. Anyone here can provide a scientific answer?

"M" wrote in message
oups.com...

steam before dumping it out the exhaust.

I never quite understood why injecting water into engine will increase
its performance. I have no doubt it's true that Boeing used to do that
on their jet engines. Anyone here can provide a scientific answer?



http://www.rfc.ca/NewSite/You_asked.htm

Double whammy:

1. cools intake, makes an effect similar to octane increase

2. steam expansion in combustion chamber adds volume (ie: power).

"M" wrote in message
ups.com...

Icebound wrote:

http://www.rfc.ca/NewSite/You_asked.htm

....

2. steam expansion in combustion chamber adds volume (ie: power).

This sounds dubious to me. It sounds like a violation of second law of
thermodynamics. It takes energy to turn water into steam, and that
steam gives that energy back by expansion, but not more than the energy
it absorbs to vaporize in the first place.


They could be arguing that the heat needed to vaporize the water would
otherwise have been lost anyway.... into the exhaust gases, or into heating
the metal of the engine, for example.

The physical details of the process may be a bit murky, but the idea that
the temperature of the engine exhaust and the engine itself would be lower
gives a bigger DeltaT that should be converted into mechanical energy to
pull the plane.

--
Best Regards,
Mike
http://photoshow.comcast.net/mikenoel
"Icebound" wrote in message
...

"M" wrote in message
ups.com...

Icebound wrote:

http://www.rfc.ca/NewSite/You_asked.htm

...

2. steam expansion in combustion chamber adds volume (ie: power).

This sounds dubious to me. It sounds like a violation of second law of
thermodynamics. It takes energy to turn water into steam, and that
steam gives that energy back by expansion, but not more than the energy
it absorbs to vaporize in the first place.


They could be arguing that the heat needed to vaporize the water would
otherwise have been lost anyway.... into the exhaust gases, or into
heating the metal of the engine, for example.

I wonder if this is not done more in all the internal combustion
engines, if it can truely increase thermo efficiency?

"M" wrote in message
ups.com...

Icebound wrote:

http://www.rfc.ca/NewSite/You_asked.htm

Double whammy:

1. cools intake, makes an effect similar to octane increase

I found this http://www.rallycars.com/Cars/WaterInjection.html. So the
benefit of #1 is obvious.


2. steam expansion in combustion chamber adds volume (ie: power).

This sounds dubious to me. It sounds like a violation of second law of
thermodynamics. It takes energy to turn water into steam, and that
steam gives that energy back by expansion, but not more than the energy
it absorbs to vaporize in the first place.


The heat absorbed by the water reduces the peak temperatures and allows the
engine to be run at a higher boost / spark advance / compression ratio
without detonation. To take advantage of the water injection, you have to
make actual changes to the engine - just adding water to an engine that is
not being limited doesn't give much benifit.

There are some efficiencies due to the specific heat of water and/or the
ratio of specific heats at constant pressure vs constant volume - but I
don't recall the details off the top of my head, and I'm too lazy to go look
it up (reference books are at work, and I ain't).

The downside, of course, is that if you _need_ the water to suppresss
detonation and your water tank is empty or frozen you can kiss your pistons
goodbye.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

: I never quite understood why injecting water into engine will increase
: its performance. I have no doubt it's true that Boeing used to do that
: on their jet engines. Anyone here can provide a scientific answer?

As others have said, it's not that the water increases its performance.
Rather, it's that the water allows operation under conditions that would otherwise
destroy the engine (in particular, lots of turbo/supercharge boost). It's analogous
to higher octane fuel. Higher octane fuel does not increase performance. Rather, it
allows the engine to be tuned to a higher compression ratio without destroying itself
from detonation. The higher CR is what increases performance.

-Cory

--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
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