"Water Powered" cars

[Magiver]

@matt

It’s already steam. Hydrogen-oxygen combustion produces gaseous water, not liquid water, as a consequence of the energy of its own combustion.

There is already plenty of steam in the cylinder and the exhaust, because the fuel already contains plenty of hydrogen bound into the molecules. Gasoline is a hydrocarbon fuel, mainly heptane, C[sub]7[/sub]H[sub]16[/sub]. It burns to form CO2 and steam. A trace of hydrogen and oxygen would fractionally increase the amount of steam, which wouldn’t do a whole lot.
You’re thinking in terms of water supplementation, extracting extra work from the waste heat usually lost to the cylinder walls. But adding hydrogen and oxygen does not result in liquid water in the cylinder, which can then flash to steam. It just adds a tiny amount of steam to all the steam that was already there. And that steam is hotter than the cylinder walls, so it loses heat to them, instead of extracting heat from them and converting it to work.

Liquid water in the cylinder doesn’t increase efficiency anyway, because the engine cycles far too fast for heat transfer from the cylinder walls to the water droplets. Crowther’s six-stroke won’t work as described. A different design whereby pressurised cooling water is heated to several hundred degrees in the cylinder cooling channels, and then injected in a fifth stroke and exhausted in a six stroke, would work. It would flash to steam from its own heat content when it escaped its high-pressure confinement. But that’s a different topic entirely to hydrogen supplemenation. Google “bottoming cycles” for more than you ever wanted to know!

Thanks, I’ll wade through the bottoming cycles references. Please don’t think I’m promoting this system. However, I’ve studied a number of them and I think it is a form of water injection. I’m not capable of arguing with you (on a physics level) regarding heat transfer rates but I’ve dealt with water injection before on performance cars and it makes a significant difference. How the introduction of hydrogen affects this I don’t know but from reading various experimentor’s results it’s clear that the ratio of water to alcohol is important to the process which leads me to believe there is either a water expansion effect from the hydrogen burn or an induction of additional water vapor in the process. Simply looking at some of the units in action I think they are pulling water vapor in during the process. If that’s the case then it should be simple to measure the gas production per liter of water and compare that to the amount of water consumed.

[matt]

@Magiver

I’m not capable of arguing with you (on a physics level) regarding heat transfer rates but I’ve dealt with water injection before on performance cars and it makes a significant difference.

Oh, absolutely! Water injection (usually a water-alcohol or water-methanol mix, IIRC) certainly has been used in performance cars and aircraft engines to boost power. But in these cases, it works by cooling the mixture drawn into the cylinder, allowing for greater charging. The effect is not dissimiliar to fitting a supercharger, for the same reasons. It’ll net you more power, but not more effciency.

This cooling effect can also push your no-knock compression ratio limit upwards, so an engine that is ALWAYS water injected can have a higher compression ratio than otherwise. That WILL give you more efficiency, but it needs an engine especially designed for it. Simply retrofitting water injection to the intakes of an existing engine shouldn’t make it more efficient.

@Magiver

Simply looking at some of the units in action I think they are pulling water vapor in during the process. If that’s the case then it should be simple to measure the gas production per liter of water and compare that to the amount of water consumed.

That is interesting, and is an aspect of the devices that I wasn’t previously aware of. I do wonder whether some of the performance improvements reported for these devices actually result from the devices acting as a bypass around the air filter?