[Stoves] iCan Trash Can Style - very clean burning

[Jock Gill]

Julien,

My hope for the combustion chamber concept  is that it will:

1. Increase residence time;
2. Increase turbulence/mixing;
3. Yield a hotter gas;

All of this will be helpful in minimizing creosote and soot.  A hot enough combustion chamber will ‘crack’ and burn the tars that would otherwise form creosote.

Good mixing and more complete combustion of the CO will reduce the ability of soot to form on cooler surfaces, such as pots.

Hence cleaner stack gases and cleaner cooking pots.

The proof is in the pudding.  I am pretty happy with the photo of the ‘pot’ bottom after 29 minutes over the fire.

As they say: Show me.  Don’t tell me.

Cheers,

Jock


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

+1 (802) 503-1258

Stewardship, not dominion


On May 26, 2014, at 11:52 AM, Julien Winter <winter.julien at gmail.com> wrote:

> Hi Jock;
> 
> The idea of the combustion chamber between the flame retention disk and the deflectors is an interesting one.  I take it that the intent is to slow the flux of heat upward, thereby increasing the temperature of combustion reactions.
> 
> Initially, I had thought of the flame retention disk as functioning to divert pyrolytic gas toward the secondary air holes, and improve mixing fuel and oxygen at the origin of the flame.  However, the flame retention disk will also keep the combustion up by the secondary air.  I posted an observation on the Stoves listserv a few weeks back, that in an open burner, the pyrolytic gas doesn't rise straight up from the fuel/char bed, but goes to the sides of the reactor, and forms a toroid-like cloud under the secondary air holes.  I speculated that hot combustion gases in the center of the burner were forcing the pyrolytic gas to the sides.  Your flame retention disk would prevent that from happening, but at the same time, it still directs the pyrolytic gas to the sides.
> 
> One problem, that I expect you are thinking of, is that the optimum depth of the combustion chamber could change with the rate of pyrolytic gas production (i.e., superficial velocity of primary air), or at a minimum, should be designed for maximum power, but still function at lowest power.  In the final design, the size of the combustion chamber may be adjustable.
> 
> (p.s.: In my previous reply to you, I notice that it also went to the Stoves listserv.  I didn't mean that to happen, because you hadn't posted your original email there.  It would seem that Gmail had snuck the Stoves listserv into my list of recipients without my knowing.  Sorry about that.   I find that Gmail has a "Bart Simpson" attitude, just like my Jack Russell Terriers.)
> 
> Cheers,
> Julien.
> 
> 
> On Mon, May 26, 2014 at 11:11 AM, Jock Gill <jock at jockgill.com> wrote:
> Julien,
> 
> The flame retention disk is BELOW the secondary air.  The Flame retention disk and the thee deflectors form what might be called a virtual combustion chamber.  One question is what is the best vertical distance between the flame retention disk and the three deflectors:  i.e. what is the best depth of the combustion zone?
> 
> I agree about the engineering.  It maybe that Dartmouth’s Thayer School will do some work in this domain. I am working with their  Humanitarian Engineering group based at the Thayer School of Engineering.
> 
> Cheers,
> 
> Jock
> 
> Jock Gill
> P.O. Box 3
> Peacham,  VT 05862
> 
> +1 (802) 503-1258
> 
> Stewardship, not dominion
> 
> 
> On May 26, 2014, at 10:48 AM, Julien Winter <winter.julien at gmail.com> wrote:
> 
>> Hi Jock;
>> 
>> Thanks for the photographs and detailed description of your stove.  It is interesting to see what you are achieving with the "flame turbulence" hypothesis using your deflector disks. 
>> 
>> Is your central flame retention disk above or below the secondary air inlet?   If it is above the secondary air, have you included your flame buffer cylinder and paraphernalia?
>> 
>> Once developers like us have some promising prototypes, it will be good if the investigation is taken-up by a well equipped laboratory, because there are important variables that we are not equipped to measure.  In particular, the superficial velocity of primary air, velocity of exhaust gases with concentration of CO and particulate emissions.  Reaction temperatures would be useful as well.  The properties of our burners need to be measured on a variety of fuels, and over a range of superficial velocities.
>> 
>> At the moment, we are frustrated by being able to make only qualitative judgments.  But the good thing is that the qualitative observations are pointing in the right direction for someone to developed a research proposal to get some solid funding.  Except for the recent article by Birzer et al., 2013 in the Journal of Humanitarian Engineering, there are no peer-reviewed articles on the science of natural draft TLUDs. 
>> 
>> 
>> Cheers,
>> Julien.
>> 
>> 
>> 
>> -- 
>> Julien Winter
>> Cobourg, ON, CANADA
> 
> 
> 
> 
> -- 
> Julien Winter
> Cobourg, ON, CANADA

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