[Stoves] Fwd: A wisdom of Rebecca's stove

Tue Sep 3 03:29:46 CDT 2013

Dear Stovers, Crispin & Larry, 
Attached is Erin's downsized version of the attachment that was rejected by Stoves List as it exceeded the maximum message file size limit of 1.5 MB. 

Thank you, Crispin, for taking he time to give a detailed explanation on fuel consumption and efficiency.  I am continually learning from these discussions. 

The focus of my message below is on the Eco-Kalan-C and its 3 variations which attempt to separate the primary and secondary airflows.  To rank the Eco-Kalan-C models' performance, I measured the time the stoves took to boil 18.75 L of water and the amount of firewood consumed.  I am fully aware that the method I used in calculating the amount of fuel consumed is NOT ACCURATE.  Nevertheless, my measurements provide a reasonable ranking of the different models of the Eco-Kalan-C;  give a good estimate of fuel savings; and are very easy to do.   I leave it with the experts like Crispin and the testing labs to determine how fuel consumption and efficiency are to be calculated. 

To answer Crispin's question below: 
1.00kg unused wood = partially burned but left over?   No.  This is part of the 3kg of wood that was set aside for the burn but was surplus to the amount needed to boil the water.  This would be the wood which you call "wood that is still in its original form". 

0.10kg unburned wood = wood that is still in its original form.   No.  This is what you call "partially burned but left over". 

WEIGHT OF FIREWOOD USED:  

3.00 = wood set aside to burn 

0.10kg unburned wood = wood that is still in its original form 

1.00kg unused wood = partially burned but left over?  If it is ‘processed’ in some manner, meaning dried out, partially charred and so on, obviously it has a different heat content. That matters, and it is hard to check. 

0.15kg charcoal = some dry fuel equivalent, or some moist fuel equivalent, or some number of Joules. 

Warm regards from Fletcher Lake (in the Chilcotin region of British Columbia), where I am smoking sockeye salmon, 

Rebecca 

----- Original Message -----

From: "reb-kees" <ravermeer at telus.net> 
To: "Discussion of biomass cooking stoves" <stoves at lists.bioenergylists.org>, crispinpigott at gmail.com, larryw at gotsky.com 
Cc: "Rebecca Vermeer" <ravermeer at telus.net> 
Sent: Monday, September 2, 2013 12:53:18 AM 
Subject: Re: [Stoves] A wisdom of Rebecca's stove 

Dear Crispin, Larry and All Stovers, 
In the attached trials, I attempted to separate the primary and secondary air flows in the Eco-Kalan -C under the following binding constraints: 
1.  that the Eco-Kalan-C stove remains 100% clay;  and 
2.  that any change in the design of the Eco-Kalan-C has little impact on its production methods. 

I offer 2 methods of introducing the secondary air supply -- through 3 holes in the combustion chamber above the firewood (Trial #2); and through the same sized 3 holes in the Kalan at the height where the fire comes out of the vertical part  (chimney) of the combustion chamber (Trial #4).  The links will take you to a series of photos of the BURNS and WBT (my version) runs to determine the time it takes to boil 18.75 L of water in a 33L pot and the amount of firewood (star apple) consumed.  At Felipa Beach, Philippines, we use this volume of water and size of pot to cook 11 kg of rice for a luncheon of 100 + people.--still being done on a 6-year old Eco-Kalan-C that is insulated with ash.  Please take a look at the fires --can you tell if the separation of the primary and secondary airflows is contributing to a reduction in PM and CO?   How can I get to boiling faster without increasing the PM and CO? 

I also reduced the height of the front opening of the combustion chamber for the 3 variations from the regular insulated Eco-Kalan-C in oder to lessen excess air.  Without instruments and expert help, I wont really know how beneficial this modification has been.  However, I have observed the following: 
1.  The separation in airflows could not cool down the combustion chamber and the outer Kalan sufficiently to be able to touch it and not get burned.   With  the insulated Eco-Kalan-C, the Kalan gets hot but wont cause a burn. 
2.  It takes longer to boil the same volume of water with the separated airflow models than with the regular insulated Eco-Kalan-C.  I wonder if this is due to the reduction in the height of the pot supports from 11/16 inch insulated Eco-Kalan-C model to 8-9/16 inch in the separated airflow models. 
3.  The reduction in the height of the front opening of the combustion chamber and the resulting reduction in the size of the opening for the Kalan led to a wider neck around the most vulnerable part of the Kalan.  In its present form, the Kalan can hold 43kg of weight when we cook pork & beans using the Eco-Kalan-C.  With a wider neck, I expect it to carry a heavier load.  Have you seen stoves in Indonesia that can carry and cook the same weight of food & pot or wok? 
4.  It is true what Crispin said about the combustion chamber being the weakest part of the stove.  But in the insulated Eco-Kalan -C model, a cracked combustion chamber can still function effectively due to the insulating ash that holds it together. Proof of that is the reject (cracked during firing) Eco-Kalan -C stove we have used for 6 years in daily and special event cooking at Felipa Beach. 
5.  During the BURN runs (NO POT on the stove), the flames were coming out forcefully, but when the pot was placed on the stove, the fire in Trial 4 had a hard time rising.  It seemed that the air flow through the Kalan was keeping the fire down.  
6.  I love the colours of the flames from the separated airflows.  Can you tell from the photos if these are hotter fires than the one produced in the insulated Eco-Kalan-C? 

I would appreciate very much your comments and  suggestions on how to improve the Eco-Kalan-C.   Thank you. 

Rebecca 

----- Original Message -----

From: "Crispin Pemberton-Pigott" <crispinpigott at gmail.com> 
To: "Discussion of biomass cooking stoves" <stoves at lists.bioenergylists.org> 
Sent: Wednesday, August 28, 2013 8:23:36 AM 
Subject: Re: [Stoves] A wisdom of Rebecca's stove 

The principle involved is that of putting a good combustor into a supporting frame. 

Viewed dispassionately, most stovers build combustors and place a pot on top. Lots of people do not think of that as a ‘stove’. 

Paul Anderson has been pretty upfront about saying that is what he often avoids. There is a stove and there is a burner in it. In order to test for safety I want to see a tilt test used where the large diameter pots sitting on three tiny supports will fall off (= fail). 

Regards 

Crispin 

Quoting Richard Stanley < rstanley at legacyfound.org >: 

Not sweating really but glad to know it was you talking... We see the same issues happen with the rocket stove of Roks as well as (mentioned) that of Joshua Guinto. Seems all to obvious a solution eh ?  Hey, how about three stones ! for a support: Viz;  introducing the supa three stone fire.  

Richard  

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