Alcohol injection

[GuyGuy]

Hi everyone, haven't sent anything for quite a while but i did a search on alcohol injection and found nothing so i was wondering if it's something that could be done since alcohol is a good coolant.

i'm no expert on combustion chambers but i figured mayby...
Thanks.

 

[TDIMeister]

Yes, it has been considered by me. Has anyone actually tried it? Not that I know of in a TDI. Under no circumstances do you want to run more than 50% alcohol/water mix or you'll be in serious trouble.

I imagine driveability is compromised because it's difficult to modulate power output with most fluid injection systems that are simply on-off affairs.

You'd be treading uncharted territory so I wish you good luck.... unless I beat you to the punch

 

[GuyGuy]

But wouldn't be like propane injection, when the pedal reaches a certain point it flips on the auxiliary system to inject a SMALL quantity of alcohol.

or is alcohol just too (clean) to mix properly or do damage???

 

[mickey]

Interesting concept. I don't think we've talked much about this. Alcohol in the fuel is a bad thing, because it wrecks the fuel system. But injected into the intake airstream? Why not? It mixes perfectly with water. And it not only evaporates more quickly (better cooling) but it is, itself, a "fuel."

At issue would be the tendency of the alcohol to pre-ignite. Any fuel that you mix with the intake air needs to have an extremely high octane rating. The diesel burn should ignite the alcohol, not the other way around.

It's worth noodling over. I've been wanting to try natural gas injection, but you have to carry around a tank that is pressuriezed to 3000 psi. That doesn't thrill me.

-mickey

 

[GuyGuy]

that's also a very good point.
Those of you who inject propane i presume it's in the air stream (i would think as close as possible to the intake valve to try and prevent a gas chamber)(go boom no).

Does anyboby know what the octane numbers and properties (good bad)are for

natural gas
propane
alcohol

 

[mickey]

When propane or NG are injected, the mixture is far leaner that it would be if you were burning the stuff in a gasser. That helps the "octane" question. It'll tolerate a much higher compression ratio that way. Too much of the stuff, though, and you get SEVERE detonation and engine damage. You must be CAREFUL!

Find out what the air/fuel mixture should normally be when burning alcohol in a spark-ignition engine, and make sure you keep the mixture a LOT leaner than that.

 

[mickey]

There are two ways to approach these kinds of mods: As performance mods, or as economy/environmental mods.

For performance, a simple boost-toggled "on/off" switch would do. You only inject your auxiliary fuel when the boost is high. Boost switches are readily available.

For economy/emissions, you'd want the injection to be proportional to airflow. This is a bit more complex. You'd almost have to use the MAF signal. And you'd also want to ensure that when you're coasting in gear, and the injectors are shut off, your auxiliary fuel flow is also shut off.

-mickey

 

[mickey]

The alcohol doesn't have to "ignite" by itself. The diesel burn ignites the alcohol. That is the idea behind all of the "auxiliary fuels", whether propane, NG, or whatever. They don't ignite until the diesel is injected and begins to burn, but when they DO burn, they burn HOT and help to more completely use up the diesel fuel. That's why you get more than a "one for one" result from propane. It helps to squeeze the last bit of efficiency out of the diesel burn.

Propane and alcohol would both have a pretty decent energy content. Natural gas has considerably less. I would guess that alcohol would be a "performance" mod, similar to propane, if you can get it to work. Natural gas has such a poor energy content that it wouldn't tend to help the power output much. The idea would be to improve fuel economy, and reduce emissions.

-mickey

 

[mickey]

I'm surprised the Brain Trust hasn't chimed in yet. Come on, guys! Wake up!

Questions:

1. Would a very lean mixture of air and alcohol be able to survive the TDI's compression without pre-ignition? Would the diesel "burn" ignite and consume the alcohol? Would the alcohol "burn" contribute anything useful?

2. Would it be better to use straight alcohol, or to mix it with water?

3. Methanol or denatured alcohol?

4. What would be the effect of this experiment? Any guesses? Huge explosion?

-mickey

p.s. I envision a smallish tank, 3 or 4 gallons, per tankful of diesel fuel. The injection system should be quite simple to design. As long as it can be made proportional to some existing sensor signal, and shut off when the injectors shut off, it should work.

 

[GuyGuy]

Well i found this.

Because of the fact that diesel engines do not use conventional spark ignition systems, it's difficult for pure alcohol to ignite within the combustion chamber. This, coupled with the fact that diesel injector pumps won't tolerate water, could be a problem ... especially if the alcohol used was not nearly pure.

Fortunately, there are several other ways to utilize homemade ethanol in a diesel engine by introducing vaporized alcohol to the engine along with diesel fuel. Probably the simplest way is to mount an automobile carburetor right on the diesel's air intake manifold and supplement the diesel fuel with alcohol metered through that piece of equipment. Of course - just as in a conventional gasoline engine - as incoming air rushes down the air inlet tube, it will pick up alcohol vapor metered through the carburetor ... which should have a controllable throttle to match tractor load.

Another way to use ethanol in a diesel engine is to install fuel injectors into the intake manifold to accomplish the same result. This system would require a separate pump that would have to be timed in order to inject alcohol at the proper moment.

A vaporizer - like those found on propane fuel systems - can also be used to add alcohol to the diesel fuel system. This, again, provides the diesel intake manifold with ethanol vapors that help combustion.

Since a diesel engine has closer tolerances and is more costly to repair than a conventional gasoline engine, you should take extreme care when altering and running diesel equipment on other than pure diesel fuel. If you don't consider yourself competent to work on diesels, find someone who is ... since the diesel fuel injector pump must be adjusted to provide less flow when alcohol fuel is used, plus the fact that a lean mixture condition - and even increased horsepower outputs - can damage a diesel engine in short order.

Turbocharged diesels can be equipped with what is known as an "aquahol" injection system, to be marketed by the M & W Gear Company of Gibson City, Illinois early in 1980. This setup injects a fine mist of alcohol and water in a 50/50 ratio directly into the engine's air intake, which results in a lowering of fuel consumption and a tolerable increase in horsepower.

http://journeytoforever.org/biofuel_library/ethanol_motherearth/me2.html

 

[PWM]

Ah - we are back again on the fumigation !

Yes, methanol and ethanol will work ..
.. ALSO fumigated diesel oil will work (this is documented in several SAE papers) !

The trick is that fuel / air mixture must be lean enough.
If the mixture is very lean those spontaneously oxidized fuel molecules do not release enought energy to cause a chain reaction (combustion).
Therefore a lean mixture will not combust in traditional way - regardless of the octane / cetane rating of the fuel.
What happens instead is a pressure and temperature induced cracking (long molecules are broken down and partially oxidized).
This cracking process is endothermic thus reduces the compression work.
Oxidation is exothermic and thus contribute to the expansion work.
Therefore it is possible to get the fumigated engine to run without combustion

(This has been demonstrated on some lab experiments ...)

And to the practical things ...
Alcohols can be fumicated simply by spaying directly to the intake. (Like water and alcohol/water -mixtures.)
This spraying cause some relatively large droplets to enter the combustion chamber. These droplets cause localized rich mixture areas. These rich areas may initiate the spontaneous combustion - but here the fairy high octane of alcohols help.
With diesel oil fumigation the problem is to have good homogenous lean mixture. (Because of the low octane - or high cetane - the mixture must be free from any richer mixture areas to avoid spontaneus combustion.) This lean mixture can be with heat evaporation or ultra fine misting (fogging). Heat evaporation simply works by heating the oil (boiling it directly or sparying a superheated fluid trough nozzle - The latter requires a high pressure heated injection system.) Fogging can be implemented with pressurized air ejectors or with ultrasonic (cavitation) fogging.

So the alcohol injection should be fairly easy to try out.
Oil fumigation might be worth to develope because no separate fuel is needed.
(Altough alcohol probably delivers more additional power trough evaporation charge cooling.)

 

[TDIMeister]

Originally posted by mickey:
Questions:

1. Would a very lean mixture of air and alcohol be able to survive the TDI's compression without pre-ignition? Would the diesel "burn" ignite and consume the alcohol? Would the alcohol "burn" contribute anything useful?

2. Would it be better to use straight alcohol, or to mix it with water?

3. Methanol or denatured alcohol?

4. What would be the effect of this experiment? Any guesses? Huge explosion?

-mickey

<font size="2" face="Verdana, Helvetica, sans-serif">1) Yes, yes, yes.

2) Mixed in water definitely. No more than 50%. Determine by experimentation.

3) Methanol, but doesn't matter so much.

4) Effects: reduced IAT, more power. To much alcohol in the mix will result in a very unpleasant knocking sound coming from the engine

Maybe wrecked pistons, blown head gaskets, bent rods.....

Sorry, I'm in a rush to go out on a road trip.

 

[Rapt]

Anywhere...

Most hardware stores/home improvement places sell it as Methyl Hydrate... Thats simply methyl alcohol with some (small) % of moisture in it. As opposed to chemically dried methyl alcohol...

Used for solvent, fuel, gas line antifreeze...

 

[mickey]

Okay, now I'm getting excited!

Where does one buy large quantities of methanol or denatured alcohol reasonably cheaply?

-mickey