Water injection
Water injection
(OP)
I know there are a couple threads on this, however I know the reason mainly is to keep things from melting on high power production mills. However, I know the arguement on guys who favor the system and the ones who say you can't make power with water because you can't burn water. I had this lurking question in my thoughts today at work talking to a friend about an engine.
Anyways, since H2O is two hydrogen and one oxygen, would the combustion process break the water down and allow the oxygen molecules become useful for continuing power production with our power stroke?
Anyways, since H2O is two hydrogen and one oxygen, would the combustion process break the water down and allow the oxygen molecules become useful for continuing power production with our power stroke?





RE: Water injection
"At elevated temperatures water molecules split into their atomic components hydrogen and oxygen. For example at 2200 °C about three percent of all H2O molecules are dissociated into various combinations of hydrogen and oxygen atoms, mostly H, H2, O, O2, and OH. Other reaction products like H2O2 or HO2 remain minor. At the very high temperature of 3000 °C more than half of the water molecules are decomposed,"
You will have a very unhappy little engine if much of the gas is at 2000 deg C, never mind 3000. You could add some powdered platinum to improve the dissociation rate at lower temperatures.
http://www.eng-tips.com/viewthread.cfm?qid=189819
has some interesting numbers
Cheers
Greg Locock
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RE: Water injection
Mike Halloran
Pembroke Pines, FL, USA
RE: Water injection
Your idea about a Platinum catalyst is interesting. Lowering the energy barrier to H2O dissociation should make it all the more effective.
FahlinRacing There is nothing to be gained from the extra Oxygen when water dissociates. The best energy yield is for the Oxygen to recombine with the Hydrogen. Net energy = zero. However, the afor mentioned reduction in combustion temperature and concurrently peak pressure, lowers the efficiency of the engine. The power gain is due to the ability of the engine to withstand more boost or CR without detonation.
BTW when all is considered, mixing alcohol, a fuel -especially Methanol, will get you more ultimate power than water alone despite the fact that water alone is a better anti-detonate. This is due to the trade-offs wrt efficiency.
RE: Water injection
Hence water increases VE while alcohol reduces it, however alcohol ads energy per unit of oxygen burned vs oxygen burned by hydrocarbon fuel.
Regards
Pat
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RE: Water injection
I am believing that nothing changes between the diesel engine and a gas engine in terms of water injection since the ICE uses the water to prevent detonation through latent heat of vaporization?
If we benefit from anything produced here would the steam produced be larg enough to see a difference even with a small amount of water steam still expands quite a bit in comparison Hmmmm. Thanks for giving me some stuff to think about to at work.
Jim
RE: Water injection
Regards
Pat
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RE: Water injection
As for the steam engine effect, after combustion, the mixture is so hot everything is a gas. The water from combustion and the injected water are not different. What counts is the pressure, not the composition of the gas (although the specific heats of steam are slightly different from N2 and CO2). As mentioned, the extra water REDUCED the peak pressure. The trade off of reduced peak pressure and increased late pressure should be a net loss. To get around the reduced peak pressure problem and get the benefit of steam expansion, the Crower 6-Stroke engine separates the combustion and steam expansion processes.
RE: Water injection
RE: Water injection
RE: Water injection
Some claim that hydrogen being added to the mix in the chamber catalyses the reaction to burn the hydrocarbon (there is already plenty of oxygen there from the air) but I have never seen credible evidence to support this. I have seen credible evidence it makes no difference at all, therefore claims by people selling such devices are snake oil.
Regards
Pat
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RE: Water injection
RE: Water injection
RE: Water injection
I think Patprrimmer was right,"snake oil"! IMHO
RE: Water injection
Either way, the oil must warm up to flash off the water before there is enough to cause emulsification. It must flash of at a reasonable rate so it does not destroy the oil film on the bearing journal as it flashes off.
The journal is the point where the oil most likely reaches water boiling point and to much water will turn to a lot of steam at 212 deg f. To much steam and not enough oil left on the journal will destroy bearings.
Regards
Pat
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