[Stoves] Fuel Testing

[frank at compostlab.com]

Stovers,

My thinking is we need to get back to the simple measurements regarding fuel
and how they are stacked because these are the things that make the most
difference. 

Simple Equipment Needed;
1) BALANCE: Weight and Volume measurements. I suggest attaching a spare fuel
box, or container of the same size as the fuel compartment in the stove to be
tested, to one end of a board about six feet long. On the other end attach a
group of liter graduated cylinders. Add weight where needed so it will balance
like a see-saw.     
2) STOVE or heat source to dry fuel and more heat to ash the fuel. 

Data we need:
1) Volume of the stove compartment. Add a plastic bag inside the ‘stove’ side
of the balance then fill with water. Determine the volume of water by filling
up the cylinders with water on the other side until it is in balance. 

2) Weight of only the fuel. Add some fuel to the ‘stove’ side and then water
to the cylinders until the weight is known.  mls = grams

3) Volume of same fuel; Use the Sand Flow Method OR wrap the fuel in plastic,
place into the fuel box and fill with water. Remove the fuel and weigh just
the water left. The difference of this water and the water when measuring the
entire box is the volume of the fuel. The fuel density can now be determined
in g/cc. 

4)  Moisture of the fuel; Dry this same fuel on the hot stove and re-weigh to
determine the water loss. The percent moisture can now be determined. 

5) Ash; Use this same fuel in the stove and collect the ash. Weigh the ash if
there is enough to determine percent ash. To convert grams ash to cc divide by
2.65. Mostly used for manures.

6) Organic Matter; The total dry fuel - ash = organic matter. Convert OM to
organic carbon (OC). If there is over 75% OM then OM/2.1=OC. If the OM is less
than 25% then OM/1.89=OC. Between 25 and 75% use ~1.95.

Calculate all the measurements to 100 cc volume. 
We can get the weight of 100 cc of fuel.
We can get carbon density per 100 cc unit of fuel
We can subtract the volume of water in the fuel and the volume of ash in the
fuel to get carbon density in the volume that is left. 

Fuel Carbon density/100 cc fuel
This determines the total heat energy in the fuel. 

Fuel Carbon density/OM-air space in 100 cc fuel. 
This determines if the fuel has a lot of surface area and will burn fast and
hot like a bundle of pine needles or little air space around the carbon so
will burn like a block of wood. 

(I think some of the carbon should be subtracted from the total to take into
account removing the water)

The above is regarding the ‘fuel’. The fuel can be cow patties, sticks of
wood, bricks of paper, pine needles tied in a bunch, - about any unit of fuel. 

Now I suggest we determine the packing of the fuel units in the stove. Pack
the fuel box side of the balance as you would the stove. Weight the fuel.
Determine how tightly packed the fuel is by determining the air space around
the fuel. Volume of stove - volume of total fuel = air space.

I was going to make an excel spread sheet with the above calculations but it
seems few are interested, or think important this type of data to help design
stoves. I am getting busy, thinking of other projects and my time is up.  IMO
the above is VERY important. 

Frank

www.compostlab.com
frank at compostlab.com