Pure hydrogen injection

Hydrogen is really only attractive for fumigation on a Diesel engine because of its high autoignition temperature.

The danger of fumigating any fuel in an engine is pre-ignition. There are a few PowerStroke guys who've broken rods due to excessive propane autoigniting too early on the compression stroke. It's the same thing that happens on a gas engine when you are fumigating a too-low octane gasoline with too high compression.

Hydrogen autoignites at 932 degrees. Diesel at 454, propane at 842, gasoline around 536 (depending on octane value), methanol at 878.
http://www.engineeringtoolbox.com/fuels-ignition-temperatures-d_171.html

So if you are running hydrogen fumigation, you can operate at a higher compression ratio (or a higher boost level) than with the other gasses and not worry about preignition.

But the main goal of fuel fumigation is to get energy into the cylinders without using a very expensive direct ignition system. And when it comes to that, hydrogen has a lower amount of energy per mole than methanol or propane. I can't find the exact numbers, but to get the same amount of energy into the cylinder you're going to need to be fumigating a lot more hydrogen than anything else; hydrogen is a smaller molecule, but it displaces as much volume as a bigger molecule due to the kinetic molecular theory. So you're going to need to displace a lot more air with hydrogen than with propane or methanol to get the same amount of energy.

Another problem I have heard of with hydrogen is that it produces a very slow flame front when compared to propane or methanol. The main advantage of fumigating a fuel is that it doesn't get harder to do at high RPM's; the piston itself is pumping in the fuel instead of an injection pump doing it. But, since hydrogen burns so slowly, past a certain (relatively low) RPM it's just going to afterburn and increase you're EGT's. I don't even know how to verify that with numbers, but I've heard of it being a major limiting point to large displacement and high speed hydrogen engines.
 
Begle1 said:
Hydrogen is really only attractive for fumigation on a Diesel engine because of its high autoignition temperature.

The danger of fumigating any fuel in an engine is pre-ignition. There are a few PowerStroke guys who've broken rods due to excessive propane autoigniting too early on the compression stroke. It's the same thing that happens on a gas engine when you are fumigating a too-low octane gasoline with too high compression.

Hydrogen autoignites at 932 degrees. Diesel at 454, propane at 842, gasoline around 536 (depending on octane value), methanol at 878.
http://www.engineeringtoolbox.com/fuels-ignition-temperatures-d_171.html

So if you are running hydrogen fumigation, you can operate at a higher compression ratio (or a higher boost level) than with the other gasses and not worry about preignition.

But the main goal of fuel fumigation is to get energy into the cylinders without using a very expensive direct ignition system. And when it comes to that, hydrogen has a lower amount of energy per mole than methanol or propane. I can't find the exact numbers, but to get the same amount of energy into the cylinder you're going to need to be fumigating a lot more hydrogen than anything else; hydrogen is a smaller molecule, but it displaces as much volume as a bigger molecule due to the kinetic molecular theory. So you're going to need to displace a lot more air with hydrogen than with propane or methanol to get the same amount of energy.

Another problem I have heard of with hydrogen is that it produces a very slow flame front when compared to propane or methanol. The main advantage of fumigating a fuel is that it doesn't get harder to do at high RPM's; the piston itself is pumping in the fuel instead of an injection pump doing it. But, since hydrogen burns so slowly, past a certain (relatively low) RPM it's just going to afterburn and increase you're EGT's. I don't even know how to verify that with numbers, but I've heard of it being a major limiting point to large displacement and high speed hydrogen engines.
Click to expand...

Now on to a variable injection system....
 
Why bother with hydrogen if your going to inject something else also why not use water for steam expansion.
 
Begle1, there's a bit of oversimplification in your post above. Autoignition is based on NO ingnition sources being present, in air at STP. Is that true in a diesel under normal operation? I don't think so.

In a commonrail engine, the pilot shot would be an ignition source, well before TDC. I know that shuts off at high RPM, but it's still there in the midrange, so you would be lighting off a flammable mix early (assuming you were feeding enough to create a flammable mix).

So would a tiny hotspot on an exhaust valve or on the piston surface. So would a bunch of other things. The energy required to detonate flammable hydrogen mixtures is incredibly low. I work in a plant where we used to use raw hydrogen at all kinds of temps (far beyond autoignition) and the measures we went through to ensure safety were ridiculous. The building even had giant blow-out panels so that the structure wouldn't go airborne if indeed there was the "earth shattering kaboom".

I do agree on the energy output....you'd be way better off injecting propane or acetylene, and those are much safer to handle as well.
 
Just retard the engin and find the right amount of Hydrogen and then what do you have? More power? Better mpg? Less egts? More headache than it's worth?
 
I dont know... it hurts my brain to much. People way smarter than me have a business doing this.. and there the only ones... there most certianly must be a reason for that. I put it on the back burner since I gotta owrry about the up comming biodiesel production season.
 
:badidea:

The only hold back with running hydrogen in a diesel is the conflict between the flame velocity.

I think it would knock a piston out real quick. Talk about spiking cylinder pressure.

HYDRO.gif
 
Tree DR said:
What would it take to turn off the pilot injection so the hydrogen isn't bruning to early in the stroke?
Click to expand...

It would take me turning on my computer pluging into a cable and into a duramax, opening efilive, and changing pilot injection pulse to "0." Then load tune.


*bdh*
 
Those of you at all interested in this, I suggest spending some time online doing research. I just spent about 14 hours this weekend and learned a ton. I'l be converting my shop towmotor to run on Brown's Gas first, then go from there. I plan on substituting Brown's Gas injection in place of LP, and run LP programs in my truck. Timing needs to get retarded when burning Hydrogen, on any motor.
The big challenge is to make enough on board to use less #2. There are examples online of people with generators in the cars, and lawnmowers.
Some trucking companies use the $6000 systems on each truck and claim $1500 fuel savings a month, per truck, so the thing pays for itself real quick.

This IS the future of fuel. Either get on board now, or go buy your horse and buggy...

There are no downsides to burning Hydrogen. It's not meant for an increase in performance, rather a fuel replacement/supplement. Hydrogen burns clean, you can actually breathe the exhaust! And with your own Brown's Gas generator in the bed, you can create your own fuel supplement for the cost of some KOH.
That mean's basically FREE fuel. WVO is basically free, but I've had a hell of a time talking the restaurant people into giving it to me. Water is free and everywhere.
 
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