[Stoves] RE Surface / volume measurement

[frank at compostlab.com]

Crispin, 

I like your idea and it makes me think of another.

1) Add the dry fuel to the top of a 'fire box' size container. Fill with #20
mesh sand to get the void space. We get void space and fuel space. Remove the
sand and repack the fuel. Fill with water containing a blue food coloring.
Drain and fill again with clear water, drain and measure the water and the
amount of blue that was left on the surface. The blue concentration should be
relative to the surface area.   

2) Add the oven dry fuel in a sack with some lime dust. Shake. Remove fuel and
shake to remove all the loose dust you can. Fill a 'fire box' sized container
with the fuel. Add water to the top (determine void space and wood volume)
shake and drain the water with the CaCO3 dust that coated the surface. Titrate
carbonate, measure pressure produced with HCl, or determine calcium. The total
carbonate in the water should be relative to the surface area. It will need to
be calibrated. *The water to wash the carbonates could be a known HCl solution
that could then be back titrated.   

3) Take a string and wrap it, say, exactly ten times in a spiral from one end
to the other of a log. Cut the string. Place the length of string along the
length of the log and cut that section off because that represents the extra
string needed to spiral from one end to the other (is that right?), divide the
left over string by ten to get the average circumference of the log. Calculate
the surface area and use for calibration.

4) anyone??


Perhaps in February I will have some free time to test out some of these ideas
if no one else has already done it. I agree with Crispin that the surface area
is a important measurement if we are to index fuels.


Thanks



Frank





On Sun, 7 Jan 2007 19:19:41 -0500, Crispin Pemberton-Pigott wrote
> BerichtDear Frans
> 
> I like this method the best because it will work with wood lengths 
> of different sizes and lengths.
> 
> Bark will give a problem of course, but as a method it is probably 
> as accurate as anything else mentioned so far.  Also it is quick and 
> easy.
> 
> A standard (short) 'dunking time' will give a water cling that will 
> vary with the surface roughness, and something about the roughness 
> could be noted by the tester.
> 
> The volume displaced is Archimedes joining the conversation.
> 
> Perhaps a liquid other than water would make a better assessment,
>  but at least we know water is available everywhere.
> 
> I also like the fact that the ends of the wood will be measured for 
> area.  When you put a rough-ended piece of wood into the fire, it 
> tends to burn much faster immediately than a smoothly sawn end 
> because of all the little spurs of wood.  Thus the point of 
> collecting this information, which is to predict burning 
> characteristics, will be assisted by knowing that ends of broken 
> splintered wood have a high surface area. They will pick up more 
> water and hold it long enough to get a reading.
> 
> I would call this the Displaced Water - Missing Water method DW/MW 
> and the only missing information at the moment is the factor which 
> converts the mass of missing water to area.  This should be easy to 
> obtain by using  a single diameter of wood.  There might be another 
> number we should add to the factor (k) which  is the number of 
> pieces in the test.  If the ends turn out to soak up a lot of water 
> in a short time, the number of pieces would affect the 'k' value.  
> Also the moisture content of the wood should probably be factored 
> into the determination.
> 
> It would look something like:
> 
> [Displaced Water mass in gm / (Missing Water in gm * K)]
> 
> where K is a combination of moisture, number of pieces and the area conversion.
> 
> Regards
> Crispin
> 
> +++++++++++
> Measure the depth of the water 40 cm ------>   1 L / cm    
> Push 20 Kg wood under the water for 10 seconds . Reed the water 
> level 60 cm ? 55 cm ? Difference is wood voume . Weigh the water 
> after retraction  of the wood , collect the droppings for 10 seconds 
> ! 40 - remaining water is the surface wet .
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Frank Shields
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