X.ProphetEzra.X

iTrader: (1)

I've been reading a lot about AI recently and I finally remembered where I heard about water being injected into engines before.

The Crower Six-Stroke
http://en.wikipedia.org/wiki/Crower_six_stroke

Cliff's:
Basically after the normal exhaust stroke water is injected directly into the engine at TDC and as the water hits the piston (rotor?) surface it turns to steam expanding in the cylinder and also removing the excess heat from the cylinder. The the steam and heat escape in the sixth steam-exhaust stroke.

Now there's enough of an engineering challenge in getting this working in piston engines but the proof of concept is pretty much there.

Are there any insurmountable reasons why it wouldn't work for a rotary engine? Of course I don't know how beneficial it would be with our relatively low compression and that direct injection would also be needed to make it possible but I don't have enough rotary engineering experience to answer these questions.

Thoughts?

pmrobert

The total amount of heat in the chamber doesn't change. Anyway, most residual/waste heat leaves via the exhaust gasses. I think there is an excellent thread on eng-tips.com reference the Crower ( http://eng-tips.com/viewthread.cfm?qid=234065 ) with actual thermodynamic engineers chiming in. Then again, lots of cool things have been discovered by people who didn't know they couldn't do something according to conventional wisdom. An exhaust-heated Stirling cycle auxiliary device driving accessories? That might have a positive energy return.

X.ProphetEzra.X

iTrader: (1)

The point isn't to inject the water immediately after combustion (i.e. directly into the exhaust gas) but rather on a more or less vacuous cylinder, (the next compression stroke), then when the water hits the hot surface of the piston it changes phases and expands. While it doesn't provide nearly as much power as a normal compression stroke it does provide some.

I believe the main advantages of this system are that it addresses cooling of the engine in a way very different than just transferring all that "wasted" heat to the water jacket/radiator and that it would improve fuel efficiency since there is an additional power stroke that does not use fuel.

I think the best way to set it up so that one cylinder would be in the fuel power stroke when another cylinder was in the steam power stroke to try to compensate for the weaker steam stroke (balanced of course).

Disadvantages however is that you would also have to carry and extra tank of water as a secondary fuel which would offset the mpg gained some. And there's that tricky part of having that much water where there is usually only oil gas and air.

Might not be practical but I think its a neat example of innovation.

pmrobert

Prophet, I like out-of-the-box thinking. We'll have to agree to disagree on this one. There's just not enough thermal conductivity into the rotor/piston/housing/cylinderwall/head to maintain a high enough temp. Water has an amazing, incredible heat of vaporization property (530+ cal/gm off the top of my head) which means it takes a lot of heat to make water change phase from liquid to gas. I honestly do not think that the material temp will stay hot enough for vaporization after the first couple of expansion cycles. They certainly don't absorb a whole lot of thermal energy from the actual combustion event thanks to the boundary layer; if the chamber walls actually did absorb a significant amount from each combustion event, they'd soon melt. 2300K temp for gas/air, 952K melt temp for steel, less for aluminum. Again, I'd really like to see someone actually optimally build one of these 6-stroke gizmos and let an independent testing lab have at it. My gut feeling is that they would end up like the "HOO" "hydrogen from water by battery electricity" scams. I would love to be proved wrong! I'll be back to refining the 200 mpg carburetor design I stole from Edsel in 1958...

X.ProphetEzra.X

iTrader: (1)

Well in the first link I posted Crower had a "working prototype" but since I believe the article is fairly old ('06) and there hasn't been any recent news on this development you might possibly be right.

The idea itself is just sooo attractive though.

X.ProphetEzra.X

iTrader: (1)

http://www.popsci.com/scitech/articl...strokes-genius