[Stoves] 22 second TLUD in development movie

[Jock Gill]

Kirk,

Thanks for the note. It is very much appreciated.   Glad some of my earlier work was useful. I plan to borrow some ideas for the earlier work and add them to this design.  It is very much a work in progress.  Notes such as yours and Crispin's are very helpful.

A few notes inserted below.

Many thanks,

Jock

PS:  I. Posted on Facebook as well, with an improved and edited commentary.

Jock Gill
P. O. Box 3
Peacham, VT 05862

Cell: (617) 449-8111

Extract CO2 from the atmosphere!


> On Sep 11, 2017, at 1:47 AM, Kirk H. <gkharris316 at comcast.net> wrote:
> 
> Jock,
>  
> Clean and simple design.  Very small flame.
>  
> Several things I note. 
>  
> Most of the flame is coming through the larger inner holes.  It looks like it only comes through the smaller outer holes when the inner holes are overloaded. 

Could be. I will have to check this out. I expect it is the case that the larger holes offer less resistance to the exhaust gases, and hence get favored.  I might buy another stove pipe cap and put the larger holes in the outer ring.  In this unit, the outer ring of holes is too closely spaced to enlarge much.  
>  
> See some smoke.  Could be the metal is cooling the gasses.  Can’t tell for sure but it may be coming mainly from the smaller holes.  This would make sense because they would be more efficient at cooling the gasses.
>  
> Are you routing the flame through holes to create turbulence? 

If you do not have a central hole as a concentrator, you have to vent the combustion gases one way or another.  Further you have to vent them fast enough that they do not put out the fire.  To get the right combination, ratio, of primary air, secondary air and draft is an interesting problem, especially in a non-linear system such as a TLUD.


> It doesn’t seem to need it as the flames below the holes already look turbulent. 

They are so turbulent they make noise yo can hear.

> Or are you trying to pre-mix the gas and air and then the holes are intended to be a burner? 

That Wes one idea.  But of course the combustion starts where the secondary air is introduced.  In this case, below the top plate.

> The only pre-mix TLUD I have seen is the one made by Alex English. 

There is some good work on this with fan powered designs in the Asia.

> All others I have seen are mix-while-burning designs.  More likely, by keeping the center closed, you are pushing the wood gas out to meet and mix with the air, eliminating the central column of gas.

Exactly the design goal.

>  
> It doesn’t look like the flame is getting hot enough to be clean burning.  Additionally the metal plate may be cooling it even more.  You may need more primary air for a larger, hotter flame. 

Actually, there may be too much secondary air -- as per Crispin's note.

> One positive of the outer holes could be that they interrupt the conduction of heat through the metal out of the stove.  Perhaps think of the outer holes as insulators to slow the flow of heat out of the stove, and the inner holes as the passage where the flame comes through the plate.  The outer holes keep the inner holes, and thus the flame gasses, hotter. Possibly move both sets of holes out some and enlarge the inner holes some so they can handle all the flame without needing the outer holes for overflow.

The outer ring of holes is just inside the opening of the reactor can on the bottom.  Remember, the cap has a larger diameter the the reactor can.

Given that the temperatures in the exhaust gases can reach over 1,000 degrees , it is probably good to have some cooling of the top plate.  Otherwise it might have a very short useful life?

>  
> Don’t expect clean burning at higher powers. 

Yes.  You can only optimize for a narrow range of gas production, which is very nonlinear.  It is much lower at the start, increases as the pyrolysis front approaches the primary air source (hotter) and then tails off as the pyrolysis nears completion.  Oddly it is much smoker at the end than at the start.  Not sure why, as the rate of gas production is about the same at both ends of the process.

> The plate will provide flow resistance and back pressure will build up below the plate with more gas at higher power levels.  It will be more difficult for the atmosphere to push air at this higher pressure gas.  More gas and less air will mean dirty burning.  Not a worry right now because of the small flame.

I am going to test a 2 inch deflector washer  hanging down some distance from the center of the top plate to increase the gas flow to the edges, away from the center of the cap.

>  
> I still remember your double washer stove design with the blue flame.  I think of what I took from that, to provide a confined volume for the heat to build up and crack the hydrocarbons as they pass through.  Thank you.
>  

You are very welcome.  I hope you were able to improve on that idea.  I must admit it is sometime hard to know if my experiments are useful and helpful to others.

Will keep you and the list informed of further developments.

> Good advice from Crispin. 
>  
> Kirk H.
>  
> Sent from Mail for Windows 10
>  
> From: Jock Gill
> Sent: Sunday, September 10, 2017 3:37 PM
> To: stoves at lists.bioenergylists.org
> Subject: [Stoves] 22 second TLUD in development movie
>  
> https://drive.google.com/open?id=0B_VaEkIQt-2nSU9wZlZMaE0xQzg
>    
> I believe this is a novel approach to natural draft TLUD design. Please correct me if I am wrong.
>  
> This is an unfinished work in progress. Still needs some tuning. Please see the annotatedbphotos out sent to the list a bit earlier today.
>  
> Thoughts? Suggestions? 
>  
> Thanks, 
>  
> Jock
>  
> Jock Gill 
> P.O. Box 3
> Peacham 
> VT 05862
> 
> 
> Cell: 617-449-8111
> 
> 
> Regenerate the Commons 
> 
> 
>  
>  
> _______________________________________________
> Stoves mailing list
> 
> to Send a Message to the list, use the email address
> stoves at lists.bioenergylists.org
> 
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org
> 
> for more Biomass Cooking Stoves,  News and Information see our web site:
> http://stoves.bioenergylists.org/
> 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20170911/ff03ff75/attachment.html>