[Stoves] FW: Turn down on FA-TLUD and ND comments

[Anderson, Paul]

Stovers,

The message below, and  the attached diagram, from Kirk Harris can be useful for further discussion.

Thank you, Kirk.

Paul

Doc / Dr TLUD / Paul S. Anderson, PhD
Exec. Dir. of Juntos Energy Solutions NFP
Email:  psanders at ilstu.edu<mailto:psanders at ilstu.edu>       Skype:   paultlud
Phone:  Office: 309-452-7072    Mobile: 309-531-4434
Website:   www.drtlud.com<http://www.drtlud.com>

From: Kirk H. <gkharris316 at comcast.net>
Sent: Tuesday, February 19, 2019 5:03 PM
To: Anderson, Paul <psanders at ilstu.edu>
Subject: RE: [Stoves] Turn down on FA-TLUD and ND comments

Paul,

This is nice.  You have found another technique for turn-down in a TLUD.  Dr. Larson has talked to me about controlling power from above rather then from below, but I don’t know if he had thought of this.  This concept didn’t fit with my approach, so I never pursued anything like it.  Now you have tested it and found that it can work.  I can see how the concentrator would work better than a center block for this turn-down technique.  Reducing the diameter by ½ (100mm to 50mm) reduces the area to ¼, which I think will reach the limit of turn-down for a TLUD-ND, if the power is somewhat proportional to the area.  The Wonderwerk uses the center block to protect the small flame below from excess secondary air above, which is a whole different way of using the blocking technique.

How to achieve this blocking is, as you describe, a challenge.  It would be hard enough if you design for it from scratch, but to retrofit an existing stove that is not designed for it could be extra difficult.  I would think that bringing the gasses together in a concentrator first, then igniting them at the concentrator is a good start.  Once the gasses are burning, a center block as you describe (alternating concentrator and center block), could be used to further reduce the flame.  I’m thinking a plate, with a hole in it, that pivots on a horizontal tube, like a draft control on existing stoves.  This reduces it to perhaps ¾ the area of the fuel reactor chamber.  Through the pivoting tube would be a rod that pivots a smaller plate to adjust the power down to ¼.  Attached is a drawing of what I am thinking.  This is of course an untested idea.

Kirk H.



Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10

From: Anderson, Paul<mailto:psanders at ilstu.edu>
Sent: Friday, February 15, 2019 8:57 AM
To: Discussion of biomass cooking stoves<mailto:stoves at lists.bioenergylists.org>
Subject: [Stoves] Turn down on FA-TLUD and ND comments

Stovers,
  At my home (after TLUD Summit), Suddha and I tested the difference of a central buff body (block the middle) versus a concentrator hole (block the edges when placed on the FABstove TLUD-FA when the power was turned down.

ABSOLUTELY CLEAR that the concentrator is far far far superior than trying to block the center.
Therefore, an easy turn-down with CLEAN combustion is accomplished by placing a concentrator over the top of the 100 mm diameter fuel chamber.  The hole size is proportional to the turn down:  fewer gases need smaller hole.  50 mm hole seemed quite reasonable.

How to place this concentrator onto a functioning FABstove is a question.   Options are
1.  to slide it in after turning down the air supply, or
2.  turn down air, pull out canister, place on a top, reinsert a canister.  Or
3.  fabricate a closure like on cameras (a diaphragm) – tricky and probably not functional because of metal weakness and high heat.
4.  Other solutions.

NOTE:   This might only be used with certain cooking, such as wanting a slow simmer for a long time.   Using this could lengthen the time of operation of the stove to double or more.
This is also good to know for when there is a larger fuel chamber.

This has NOT been tested / compared regarding ND TLUDs.   There are at least two currently important designs.
1.  The Champion TLUD-ND has a concentrator hole.  A very simple solution. Not much further work done on it.

2.  The Wonderwerk TLUD-ND by Kirk Harris has the combustion toward the edges of the riser by having centrally supported blocking, with several great ways to enhance mixing.

3.  What is not tried is to alternate from hole to edge or edge to hole (and back again, plus fixed-blades etc to get the mixing better.   Might not work???   So the tests are to send to edges (block center) after the concentrator hole, OR to bring together after having been mixed at the edges.

This might be a good boost for Norm’s larger TLUDs with ND.

Fair game for anyone to try.  Please tell us your experiences here on the Stoves Listserv.

Paul

Doc / Dr TLUD / Paul S. Anderson, PhD
Exec. Dir. of Juntos Energy Solutions NFP
Email:  psanders at ilstu.edu<mailto:psanders at ilstu.edu>       Skype:   paultlud
Phone:  Office: 309-452-7072    Mobile: 309-531-4434
Website:   www.drtlud.com<http://www.drtlud.com>


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