Semi Closed loop... Anyone tried it?

[fattywagonman]

Hi folks,
I've been running my Listroid semi closed loop and so far I'm impressed with the results... The "system" consists of 2 5 gal propane tanks to act as accumulators and a tube in shell cooler / heat exchanger for the exhaust.... A small air compressor supplies air to the loop.... 1/4 pipe is the exhaust... water and co2 comes out... I though some folks here might be able to use something like this  because this make the Lister  virtually smoke free... I also am running on WVO with a heated injector line...

[hotater]

Fattywagon---

I'm not running that system because I don't know what it is!  Could you explain it on a little more basic level?  What are you heating/cooling and how?
  'Smoke free..'  where does the carbon accumulate?

[fattywagonman]

Hi Hoater,
The exhaust goes through a cooler and is returned to the intake... as far as carbon goes so far no problems... combusting is very complete smoke (aka unburned fuel) is returned to the intake for a second chance at combustion... the engine runs an air compressor the air is added at the intake port...  I used 2 5 gal propane tanke as accumulators...

[Joe]

Holy Crap...what a set up...I'm such a piker...

Joe

[hotater]

Interesting concept but I'm having trouble seeing the value of it on a working engine.

If the engine produces *any* solids at all they either have to accumulate or be flushed and it looks like your system would be constantly adding carbon to either the exhaust system or the engine until it choked on it.
  If it didn't burn the first time why would it burn the second in a dirtier environment?

I've run my 6-1 exhaust into a ten cubic foot concrete pipe for just over a year and I'd bet there's several pounds of soot in the wet gravel bottom.  That's running #2 diesel and averaging about 1800 watt/hrs a day.

[Jim Mc]

...
The exhaust goes through a cooler and is returned to the intake...

Huh? There's something here that doesn't make sense.  How does the engine induct freah air for combustion?

[Halfnuts]

This sort of reminds me of how rabbits can't fully digest grass on the first pass, so they eat their first-pass "rabbit raisins" and on the next pass they are further digested.  Probably more than you wanted to know, so I'll shut up now.

Halfnuts

[hotater]

'Halfnuts' is an understatement. 

 

[kpgv]

Wabbit Anyone? MMMMM

The "Semi Closed Loop" If I get it, sounds like a "sledgehamer" EGR system.
How can it not be a "zero sum" situation.
Cold oxygenated air in>Compression>Injection and Combustion> Hot exhaust (with some unburned fuel, particulates, and all the other normal exhaust "stuff") out>
Hot spent "exhaust" (see above) in> ??out??...(???Diesel Equivalent of an Asthma Attack???) Leaky gaskets "might" help?

As Scott (shipchief) put it so eloquently:

Suck>Squeeze>Bang>Blow   (I assume oxygen is involved in the "suck" part...)

Is there something I am missing here???

Kevin

[fattywagonman]

Yup, It's kind of like the ulitimate EGR... I'm not sure about the carbon build up but I'm sure there will be some over time... right now an air compressor runs of the engine and new air is added right at the intake manifold... the exhaust is at the bottom of the intake accumulator...  I've been messing with closed loop ideas for several years... I got the idea as a way to eliminate vacuum in Otto cycle engines.  I made some carbs that used cooled EGR instead of reducing air flow.  then I realized if I added O2 I could keep the engine running on cooled exhaust... a little side note: combustion is very complete in an O2 rich working fluid but you need to be carefull to make sure the engine is firing before you richen the O2 otherwise the recirculated vapor will explode and lift the head off the cyclinder... I did this and it's really exiting but also potentially dangerous.. I was surprised it didn't bend the crank or rod but so far everything seems fine..  Then I started thinking about the possibilities of increasing the efficiency if the loop pressure could be increased...  I reground the cam to more of a Miller Atkinson cycle and have been getting some interesting results which I may share once I have some hard data for backup... I think the Listeroid is an idea test engine... it was cheap engough and seems tough enough to take the abuse I've been dishing out... just in case you are curious... I haven't been kind to my engine...     

[hotater]

Fascinating stuff!!   Thanks for sharing.

 Maybe this would be a good place for an exhaust scrubber design.?

[fattywagonman]

An exhaust scrubber?  Well the idea is comsume any unburned fuel by returning it to the intake... BTW Kevin I'm cooling the exhaust before it goes back in the engine.. and theres a seperator of sorts in the intake accumulator... O2 that doesn't get used also gets retuned to the intake... Another cool thing is the loop pressure can be increased for a turbocharging effect... 

[GuyFawkes]

what this guy is doing is reducing the nitrogen load, so he is quite likely to pass stringent emissions regulations this way, but apart from legislation I don't quite see what else it has going for it.

[Andre Blanchard]

I seem to remember something like this for running diesel engines in subs while submerged.  The O2 come from a liquid storage tank and enough of the exhaust gas was recirculated to keep the engine from melting down.  They may have also had some kind of CO2 scrubber system so any unused O2 went back to the engine.
I do not remember if it was a system that had actually been used or just some proposed idea.  Memory could also be from a SF book were they run diesel bulldozers on the moon.
_________________
Andre' B.

[fattywagonman]

While I havn't tested them yet I'm sure the emissions are low... HC's and NOX should be almost non existent... as I mentioned I've discovered other possibilities of potential efficiency increases by implementing the Miller cycle while using the semi closed loop design... I think this may be the real benefit but I'm still working on getting some real data (fuel burned vs enegy out) for comparison to the standard cycle...