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 Post subject: Crower Cycle
PostPosted: November 10, 2010, 9:59 pm 
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Time to start a new thread, things were getting pretty messy, discussing two concepts at a time.

To start things off, a real basic question: Why a six stroke engine? Couldn't distilled water, instead of fuel, be injected into each cylinder whenever the operating temperatures demanded it? All you would need would be the injector and the stuff to drive it. I thought that would be the way to go ten years ago, still seems the best.

But I am a at best, a half assed technical type of guy.

Bill


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 Post subject: Re: Crower Cycle
PostPosted: November 11, 2010, 2:17 am 
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Intake

compression

ignition

You get the picture so far ...

Exhaust valve does not open and the exhaust gas is being compressed again.

When it hits TDC again water is injected into this recompressed exhaust that now maybe around the 500C mark which turns the water into steam.

As the water turns into steam it wants to expand by around 1200 to 1500 times by volume although now it's a compressable gas so it's pressure rises dramatically, this energy/pressure again drives the piston away.

To change the water into steam requires heat which it has just used the exhaust gas heat so seeing as this heat is absorbed doing that work, the cylinder stays cool.

One more stroke from BDC to push out the old exhaust gas/steam mix and you're ready to start again.


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 Post subject: Re: Crower Cycle
PostPosted: November 11, 2010, 2:59 am 
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BBlue wrote:

Couldn't distilled water, instead of fuel, be injected into each cylinder whenever the operating temperatures demanded it? All you would need would be the injector and the stuff to drive it. I thought that would be the way to go ten years ago, still seems the best.


Bill


I believe that a gas such as acetelyne in a very lean mixture could be used to create a critical temp environment to which water could be injected into to make instantaneous steam.


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 Post subject: Re: Crower Cycle
PostPosted: November 11, 2010, 8:16 am 
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Exhaust valve does not open and the exhaust gas is being compressed again.

Whoa! Yes, it seems that is a variation on Bruce's engine, but not an integral part of the cycle and I had missed it.

While that would certainly boost temperatures, how much would you gain? First, there would be a terrific power loss as the gases are recompressed. Second, I think the pressure involved in the combustion chamber (think head gaskets), piston pin and lower end would be out of sight. (think short bearing life, broken rods and cranks)

Bill


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 Post subject: Re: Crower Cycle
PostPosted: November 11, 2010, 8:31 am 
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BBlue wrote:
Exhaust valve does not open and the exhaust gas is being compressed again.

Whoa! Yes, it seems that is a variation on Bruce's engine, but not an integral part of the cycle and I had missed it.

While that would certainly boost temperatures, how much would you gain? First, there would be a terrific power loss as the gases are recompressed. Second, I think the pressure involved in the combustion chamber (think head gaskets), piston pin and lower end would be out of sight. (think short bearing life, broken rods and cranks)

Bill


You would gain a lot, you have already expended 35% of it's heat to the surface walls and used 35% pushing the piston away, the charge is no longer expanding and is probably contracting so really it's a non issue because you have already selected a diesel bottom end that has the strength required for the extra remaining pressure.

As long as the temp is high enough to turn the water to steam you will gain even if only for cooling.

The hard part is what to do with the steam later as in recycling it back to the engine through the use of a condenser or other.


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 Post subject: Re: Crower Cycle
PostPosted: November 11, 2010, 8:47 am 
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cheapracer wrote:
Exhaust valve does not open and the exhaust gas is being compressed again.

When it hits TDC again water is injected into this recompressed exhaust that now maybe around the 500C mark which turns the water into steam.

Huh? That's not what I understand from Wikipedia:

http://en.wikipedia.org/wiki/Crower_cycle

According to that, you still get the power stroke after ignition, and a second power stroke with the water injection, using only the heat from the cylinder walls and piston to flash boil the water. That makes sense to me.

It sounds like you've come up with a modification to the Crower cycle... unless the Wikipedia article is woefully inaccurate. (I'd read through the patent to see which is right, but even thinking about reading through a patent makes me want to claw my eyes out...)

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 Post subject: Re: Crower Cycle
PostPosted: November 11, 2010, 9:01 am 
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Andrew, recompressing the exhaust gases is discussed here:

http://www.autoweek.com/article/20060227/free/302270007

I think some serious analysis of pressures would be in order. I would, but can't, just too stupid. Can't help but think the cylinder head would end up on the ceiling. If recompressing wouldn't do it, surely the steam would.

Bill


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 Post subject: Re: Crower Cycle
PostPosted: November 11, 2010, 10:32 am 
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BBlue wrote:
Andrew, recompressing the exhaust gases is discussed here:
http://www.autoweek.com/article/20060227/free/302270007

Ah, so it's a variant. The original Crower cycle is what's discussed at Wikipedia, and he's additionally started developing another one as described by cheapracer above. Interesting.

Personally, for an open engine design project, I'd go for the original idea where you get a combustion power stroke followed by a steam power stroke. That wouldn't impose any extra stresses on the engine than you'd otherwise see with regular operation (or light turbocharging), and thus you could conceivably use an existing engine with a new Crower cycle head on it.

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 Post subject: Re: Crower Cycle
PostPosted: November 22, 2010, 4:40 am 
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Ahh I see that it's been going on for a while, that would explain the differences in stories that are going around - depends on when the particular reporter reported it as to what form it was in.

In the 2006 patent the exhaust is expelled and indeed he mentions only the use of cylinder heat to change the water to steam and has a 3 valve engine illustrated, 1 exhaust for normal and one for steam recycle. http://www.freepatentsonline.com/20070022977.pdf

I read a long time ago there wasn't going to be a patent but maybe business sense took over!

In that patent he covers literally any engine but I would like to see how how can prove it for a 2 stroke.

Can't see it ever making mass production because of the need for a water recycling system and having the Greenie's up in arms about using water resources to power the "Evil Car" - they prefer "clean electric cars" (because batteries grow naturally on trees :wink: ).


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 Post subject: Re: Crower Cycle
PostPosted: November 22, 2010, 9:26 am 
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Why do you need a water recycle system? It "uses" no more water than gasoline. Distilled water is less than a buck a gallon, purchased in a plastic jug. I'd think the big problem for mobile use would be freezing water.

Have you figured out why he needs to make it a 6 cycle, not a modified 4 cycle engine?

Bill


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 Post subject: Re: Crower Cycle
PostPosted: November 22, 2010, 10:58 am 
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i still think the best way to get there from here, since a fully equipped r and d shop is out of my price range, is controlling the lifter like in the current production chrysler hemi. two of the problems to consider (and i haven't looked at the info you provided yet so i'm on the verge of blowing smoke. ..) is that a pressurized environment causes a higher boiling temp. so, you have to consider what the total Dtemp is that can be gained from both the residual chamber heat and the heat of compression as represented in the exhaust charge retained should the valve not be opened and the energy lost by not voiding the exhaust charge, uggh. i remember some research about the effects of injector shutdown on catalytic convertors and how allowing the engine to cool down too much by leaving the valves open raised undesireable emissions but i haven't seen that paper in years so i can't remember enough to quote from it. something about shutting off the intake but leaving the exhaust to function as normal was enough to keep the cylinder temps up and avoid regulatory issues. ..
another minor distraction is the ability to use direct water injection instead of egr to adjust the air fuel ratio. they do that on shipboard diesels now so the dynamics have already been worked out albeit at a much slower rpm.


one of them days. .. http://www.youtube.com/watch?v=KmTzuf2INSg&feature=related

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 Post subject: Re: Crower Cycle
PostPosted: November 22, 2010, 12:02 pm 
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Speaking of emissions, the guy that designed by ECU maintains that CO can be adequately controlled without the use of a converter and in fact, the converters function in todays cars is to lower combustion temperatures in order to control NOX. In order for all this to happen, AFR's are not optimized for power or economy, but to maintain the proper environment within the converter. If that is the case, couldn't the converter be removed and combustion temps controlled with water injection?

Bill


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 Post subject: Re: Crower Cycle
PostPosted: November 22, 2010, 12:51 pm 
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BBlue wrote:
Why do you need a water recycle system? It "uses" no more water than gasoline. Distilled water is less than a buck a gallon, purchased in a plastic jug. I'd think the big problem for mobile use would be freezing water.


Because the water (and glycol?) would dangerously be going onto the road surface, rusting the exhaust away, possible steam vision problems on cold mornings for following motorists and most of all the Greenies would be up in arms about the water mixed with Co2/NoX etc running off into the Eco system besides the water waste.

Is that enough?


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 Post subject: Re: Crower Cycle
PostPosted: November 22, 2010, 1:47 pm 
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cheapracer wrote:
BBlue wrote:
Why do you need a water recycle system? It "uses" no more water than gasoline. Distilled water is less than a buck a gallon, purchased in a plastic jug. I'd think the big problem for mobile use would be freezing water.


Because the water (and glycol?) would dangerously be going onto the road surface, rusting the exhaust away, possible steam vision problems on cold mornings for following motorists and most of all the Greenies would be up in arms about the water mixed with Co2/NoX etc running off into the Eco system besides the water waste.

Is that enough?

Not really. Stainless steel exhaust systems have been very common for about 20 years. Steam an insolvable issue? I doubt it. First, you are going to have to demonstrate it would cause visibility problems. I really doubt if it would. At idle in cold weather, very little water would be consumed. At speed, it would dissapate pretty rapidly. Heavy trucks would blast it skyward, no problem there. Glycol at 8 bucks a gallon would prolly be the last choice of antifreeze. Perhaps a drainback system with heaters could solve the freezing problem. Finally, exhaust is exhaust, what difference does it make it it contains more water than usual? Or maybe a little booze?

But first, get the thing in use as a stationary power unit. That would eliminate all of your concerns. Then attack the ancillary issues.

Bill


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 Post subject: Re: Crower Cycle
PostPosted: November 22, 2010, 7:54 pm 
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acroleins... i think thats what it is. when you burn off glycol you get them, supposedly nasty stuff. craig at neoteric biofuels knows a bit about them, he may still have a set of faqs on his website.

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