Semi Closed loop... Anyone tried it?

[fattywagonman]

Here's another link I'd suggest reading... it's a patent that describes the closed loop operation..
http://www.freepatentsonline.com/7043920.html?highlight=7043920
The idea originated in the 50"s as a way to run diesel engines underground or underwater in a submarine...

[fattywagonman]

I still don't get it.  Please help me.

Hi Steve,
I've inserted some answers below...

All I'm doing is cooling off the exhaust adding some air with a compressor driven off the crank and then sending it back to the engine intake .. ... very simple.. not rocket science..   
Are you shutting off the diesel so the engine is just running on exhaust and added O2?
NO I'm not shutting off the fuel.. the engine needs fuel to keep running

the engine will run as long as a sufficient supply of air is entering the system to keep the fuel burning... too much fuel and no air and eventually it quits...

The exhaust has limited fuel in it, once it is cycled twice is there enough fuel to keep the engine running?  Or are you adding diesel too?
Just adding fuel with the injector...

there is an exhaust port...at the bottom of the intake accumulator which is also a centrifugal separator of sorts..  water and CO2 are what comes out...
Here's where you totally lose me.  Why does only water and CO2 come out? 

Because water and CO2 is heavier than the other gasses

Why not unburned fuel?
well after the engine is running the exhaust is very clean... I think the smoke actually improves combustion...
Some smoke comes out when the engine is cold but this clears up quickly... after the engine is warmed up a bit no smoke comes out...

The exhaust can be held back to pressurize the system and increase the density of the working fluid..
What is the working "fluid"?    Why do you call it working fluid?  Is this diesel?
Here are some terms to read up on
http://www.wipo.int/classifications/fulltext/new_ipc/ipc7/ef.htm

... kind of like turbocharging without the turbo...
Why does increasing the density of this "fluid" create a turbocharging affect?
All a turbo does is pack more air into the engine... more air ='s more density... more density='s more possible fuel consumption and IMO a potential for increased efficiency

The usefullness of this is that it is quiet and nearly pollution free.. there may be possible efficiency benefits... but that has yet to be proven..

Why is this quiet?  Are you implying that it is quieter than a muffled lister that is not running on recirculated exhaust?
Yes

Maybe pictures would tell the story better.
I posted a picture

Could you provide close up pics of your entire set up?  Specifically I'd like to see how the exhaust is connected to the intake and how the exhaust port releases water and CO2 but not unburned diesel.
The picture I posted shows it all pretty well..

Finally, what are you trying to accomplish?  At first blush, "reburning" exhaust seems like an efficiency play with less pollution as a side result.  Is this what you're trying to do?
Yes sort of... In CA where I live the EPA frowns on self generators ..
 mainly because of pollution... I'd like to eliminate this problem..

Thanks,
Steve

No problem... I like discussing this stuff with folks who are nice about it...

[SHIPCHIEF]

I'm having some trouble with the separation of CO2 from the exhaust. Gas Laws state that the pressure of a gas is exerted equally on the surfaces of the container, and mixed gases tend to, well, mix. To separate CO2 from Oxygen and nitrogen, in industry, air is cooled until the gasses condense and are captured as a liquid, each at it's specific temperature. I don't see that separation is possible in your exhaust accumulator? Although the water vapor (read gas) does condense and flows out the bottom. Also, the exhaust volume is greater that the inlet air and fuel volumes, so some exhaust would always have to be released? This would be fuel rich due to the reduced inlet oxygen, and a terrible loss as well as a hyrdocarbon pollutant.
As for miller cycle, the article cited refers to OTTO cycle engines, where a reduced compression ratio is required because of the fuel. Reduced throttle operation also reduces real compression ratios, but of course limits the power output too. The altering of inlet valve timing to reduce real compression ratios does not seem to reduce pumping losses significantly, the engineer in the article was not satisfied with the result, and went on to investigate specialized turbochargers. In a diesel, we would just keep increasing ther compression ratio for more efficiency, until the engine wears too fast.......or the EPA steps in and demands a reduction in NOX. Exhaust gas recirc has been used to reduce NOX, and more recently UREA injection. Dr. Diesel intended some very high compression ratios initially. He broke some parts too, so your in good company.
The second link was interesting; a wish list for the removal of nitrogen from the inlet air supply to the engine. That would be some expensive intake air, and possibly negate any increases in fuel economy...because you would have to buy the air and the fuel both.
The other way to extract power beyond the limits of the expansion ratio is to add a power recovery device, like an exhaust turbine that returns the work to the output shaft. An example would be the wright 3360 radial engine with exhaust power recovery turbine used in the Douglas DC7 airliner just before the jet age. I supose one could use the exhaust side of a turbocharger and run a flat belt pulley from the turboshaft to the crankshaft.... The other way is to simply turbocharge the engine so the inlet air pressure pushes the piston down on the intake stroke, converting pumping losses into pumping gains. (and also increasing the real compression ratio and firing pressure)
Well, don't take my questions as disaproval, I like that you are trying this and brave enough to share....Still, didn't Solomon say something about there being nothing new under the sun?
Scott E

[GuyFawkes]

as far as emssions are concerned, the big problem is and always will be nitrogen.

nitrogen is the commonest part or air, but it is the part that produces the emissions that will fail an emissions test.

you can limit oxygen to just sufficient to consume the fuel easy enough, and that will take care of the other emissions, but you are still left with nitrogen

nitrogen and oxygen are close enough in size you can't practically filter them to separate.

the bottom line here is

1/ nitrogen by products of combustion inside an engine are harmful
2/ governments have put limits on allowable output
3/ all methods of addressing this problem are high tech and high energy
4/ all high tech and high energy solutions simply move the problem away from the regulated zone, they do not eliminate it.

so emissions regulations are essentially no more than a disincentive tax on internal combustion, allegedly purely on health grounds, with no studies of any kind made on the wider implications of such a regulation.

matey's experiments are interesting, and may lead to some interesting results one way or another, perhaps a really good way of getting thermal energy out of a CHP system, but at a cost, and that cost will inevitably be overall surplus power produced available to do work. eg generate electricity.

the sensible route would be to exempt small stationary engines from the regs, but that won't happen.

the alternative route is the one matey is going down, workshop space heaters do not have emissions regulations, he is modifying his engine such that he will be able to argue it is no longer internal combustion

[fattywagonman]

Hi Guys,
As far as the separation thing goes... there are 2 byproducts of complete combustion... water and CO2... now if you get things hot enough the O2 and N get mixed together and can make NOx... lowering the peak combustion temps with EGR... especially cooled EGR is a good way to reduce and possibley come close to eliminating NOx... loweing the compression also lowers NOX.. I've done both... I think my NOX emission will be nearly non existent...
Here's a link to some NOx informayion
http://en.wikipedia.org/wiki/Nitrogen_oxide#Thermal_NOx
Most diesel have a NOx problem because of 2 reaons... too much O2 in the incomming air and high compression which ='s higher peak combustion temps.. they system I'm using returns the exhaust to the intake.. after the engine runs for a while I believe that the  inlet is composed of a mixture of CO2 (byproduct of combusting the C part of HC's), H2O vapor (vapor that didn't condense in the cooler)   O2 (from the air being pushed in and some that didn't get used in combustion)  N (from the air being pushed in) and some unburned HC's (that didn't get used in the combustion process).. The engine can be made nearly pollution free if O2 is the only thing added... as Scott said the inlet air becomes more expensive or harder to make.... O2 separators are common in the medical industry.. they are nothing more than an air comp pusing the air through a separator that keeps the nitrogen out... there are 2 filters and every minute or 2 it switches from one filter to the other... so one cold be outfitted to the engine... in this case O2 and CO2 become the working fluid... nearly zero emission are possible...   

[cujet]

Thank you for the fantastic, thought provoking post!

I have plenty of experience with bizzare engines. Smokey Yunik's shop was right down the street from my house in the 80's. I used to visit from time to time. Always liked what he was up to. He was able to achieve some incredible things. Yes there were some problems and issues. These could be worked out with today's computer controls.

I like your setup, better pics would be really nice. I agree that things do not have to be good looking to be effective!

Have you thought about a spring loaded exhaust port to keep the system pressure up? How about using the crankcase compression to provide the pressurized air. 2 piston strokes are available in the crankcase for every intake event.

Chris

[pigseye]

Hi FW,
I apologize for my ignorance on semi closed loop systems.  Your responses were very helpful, they really clear things up for me.

Your post has been very thought provoking.

Thanks,
Steve

[fattywagonman]

Hi Chris,
That's neat that you got to see Smokey Yunick in action...  I've heard that Smokey did achieve some really impressive efficiencies from the IC engine...  I was told by a friend that he ran one engine without a cooling system... that he found a way to scavenge the heat from the cylinder and head and return it to the cycle... I'd imagine that most of his modifications were cam / compression related... Any ideas?

[hotater]

Smokey Yunnick and Dale Inman and other old time NASCAR guys could get horsepower and speed out of nearly anything!!
My Dad and I went to the Daytona races on the beach from '53 to '58 then at the new track until '62.  I was within splatter distance when Gene Curtis hit the seagull with his 1955 Keafauver Olds Super 88....JUST like the one we drove down there!!
Fireball Roberts was *my* guy. 

[fattywagonman]

Here's a link to another interesting patent relating to low emission using semi closed loop... it's own by the EPA!
http://www.freepatentsonline.com/7047933.html?highlight=7047933

[SHIPCHIEF]

That was an interesting link.
It requires that the O2 supplied for combustion be known, by calculation or by measurement. (We usually think of O2 sensors operating in the hot exhaust instead of the cool intake), variable injection timing, Special fuel, a charge air compressor (supercharger) with a controlled throttle, exhaust gas recirculation with a controlled throttle, with the combination pressureizing the intake manifold to some desired value. That alone sounds like it needs microprocessor control. In this case the recirculated exhaust is intended to be devoid of unburned fuel, so the explosion hazzard is not there. The bulk of the exhaust is released to the atmosphere, supposedly clean.
Then the quality of the exhaust must be monitored and feedback given to the processor to continually adjust for load control, and emission control.
And that's just skimming the info from the link...
I am no expert, but the dillution of the intake oxygen, and the low combustion temperature equate to low power density and poor economy. Both are totally unacceptable in transportation where bulky machinery takes away payload, and higher fuel costs increase operating costs.
Scott E

[fattywagonman]

Personally I like the idea of an O2 rich mixture with a closed loop... This only works with diesel since the fuel is injected at the time of combustion... It also lso results in a nearly zero emission engine... unused O2 is returned to the intake... with any uncombusted HC's for another shot at combustion...   

[Jim Mc]

...Because water and CO2 is heavier than the other gasses ...

What?  You're saying that water vapor and CO2 will 'fall out' of a mixture of unburned gasses because they have a higher density?  No way.  A mixture of gasses can not separated that way. 

[BobH]

Fattywagonman.

I think you will learn something by posting on this forum. There are a few really smart people who have all the great ideas, and the rest of us they make look foolish. Einstein once said " GREAT IDEAS HAVE ALWAYS BEEN COUNTERED BY MEDIOCORE MINDS ". That is true on this forum. You can spot the smart ones by looking at the number of posts.

[fattywagonman]

You're saying that water vapor and CO2 will 'fall out' of a mixture of unburned gasses because they have a higher density?  No way.  A mixture of gasses can not separated that way.

I don't mind being corrected.. as long as it's constructive.. and I realize that some folks are just nicer about it than others...  Jim, You're right... Gases don't seperate into layers... once they are mixed they stay mixed..... but water vapor can be condensed and CO2 is a heavy gas... I think part of the sucess with my system has to do with the design of the intake accumulator / propane tank and the way that the recycled gas enters and leaves the container.. ... The cooled exhaust is being returned in such a way that is spins the gasses.. like a cyclonic separator for sawdust that mills use... the intake is in the center of the top.. where the clean air would come out.. the exhaust exits  in the center of the bottom.. where the sawdust would leave..

Yes some folks have a hard time with new thoughts... and sometimes you take some heat for having them... but I've learned that recieving some criticism is  just part of the price you pay for unconventional thinking...