[Stoves] Fuel Testing

[frank]

Dear Crispin,
A few questions from someone on a steep learning curve.

How is the "Remaining Carbon Left in Combustion Chamber" measured?  Is 
it by Leco or such?  Because that could contain a lot of carbonates and, 
if I understand it, the carbon from carbonates should not be in the 
calculations for carbon energy. Manures can have a lot of carbonates and 
I suggest they must first be removed before determining the OC.

And again for my 'Stove 101' lesson: Where does the 'Energy in Gas' and 
Energy in Charcoal' numbers come from?

Portion of wood that is gas = OM?
Portion of wood that is charcoal = ash?

Thanks
Frank




Mass of Wood
Remaining Carbon, left in combustion chamber
Water content of wood as portion of total mass
Temperature of wood, initial
Temperature of boiling water, local
Energy in Gas
Energy in Charcoal
Portion of wood that is gas
Portion of wood that is charcoal
Mass of Wood after water has been subtracted
Heat released during a burn
Heat Potential if all wood was burned



Crispin Pemberton-Pigott wrote:

>Dear Andrew
>
>I was going to say that surely we could model that....
>
>But it would be more useful to model the heat loss in the steam at the pot 
>sides.
>
>I have allowed for conservative calculations when making claims for 
>efficiency because it is useless to overclaim.
>
>So, I have been deducting a bit of the 'fuel used' to compensate for 
>moisture on the basis of heating it from ambient and boiling it away.
>
>I have not added in an additional amount for the lost hot steam because that 
>does get lost in real life.
>
>Maybe what should happen is that the loss from moisture in the fuel shold be 
>calculated to a certain standard, for example to 12% (air dried) and if you 
>are using 5% moisture wood, you should subtract from the efficiency to give 
>enough energy to the heating of water that _will_ be there in the field.
>
>Actually there is merit in this.  Even it if was 10% (dry season air-dried), 
>it is a nice round number.
>
>If your wood is 16% moisture WWB you deduct at a certain rate (Andrew 
>proposes 2.7 MJ and if it is zero, you add.
>
>This is reasonable and when testing in the field, it will represent reality 
>better, and measurements made from real life tests where the moisture 
>content is unknown will be more useable for international comparison.
>
>Al things said and done, working with a round number is no easier than a 
>square number: how about we ask people what they get as the actual moisture 
>content of fuel and settle on something realistic as the heat content for 
>stove evaluation purposes?
>
>I think it is important to get away from lost-water-based testing (which is 
>for developers) and move to fuel-used testing with agreement on a heat value 
>for the wood, on the mass that forms the basis of the specific fuel 
>consumption calculation, and the basic procedure.
>
>Regards
>Crispin
>
>
>----- Original Message ----- 
>From: "AJH" <list at sylva.icuklive.co.uk>
>Subject: Re: [Stoves] Fuel Testing
>
>
>On Tue, 03 Oct 2006 13:07:04 -0700, frank wrote:
>
>  
>
>>I would think a wet piece of wood would conduct heat through the wood
>>faster. Water transfers the heat.
>>    
>>
>
>The point being that water only transmits heat up to a temperature of
>about 100C, then it turns to steam absorbing much higher amounts of
>heat than the heat necessary to reach that 100C. So there will be a
>plateau temperature held at 100C whilst the water evaporates before it
>can start rising up to pyrolysis temperatures.
>
>AJH
>
>
>_______________________________________________
>Stoves mailing list
>Stoves at listserv.repp.org
>http://listserv.repp.org/mailman/listinfo/stoves_listserv.repp.org
>
>
>
>  
>

-- 
Frank Shields
Soil Control Lab
42 Hangar way
Watsonville, CA  95076
(831) 724-5422 tel
(831) 724-3188 fax
frank at compostlab.com
www.compostlab.com