[Stoves] Fwd: Re: Building a Better Fire

[Boll, Martin Dr.]

Dear Dean,

Just want to add two things to your basics on better fire, to be re-thought
about by you, a specialist in this item; if it makes sense:

 

Quickly changeable fire:

-Speeding up quickly and stopping fire quickly, as possible with a gas-stove
would be desirable for better fire.

(I remind, Crispin has told about extinguishing a rocket stove by users,
being astonishingly useful/economic.)

Especially with simultaneously/subsequent use of a RHC (retained heat
cooker)

 

Different stove types together:

-For small stoves I don't believe that it is possible to turn down the fire
to fit minimal simmer-power without spilling energy.

I expect, we have to think about a somehow *activated* RHC, and use it after
the normal heating.

To say it somehow *overdrawn* I would say: Building a better fire is
building different good fires.

 

The problem of *activating* a RHC is therefore for a long time in my mind
and I am thinking of different possible solutions.

 

But let me think about another global aspect.

If we would partly stop total burning:

In areas, where wood is no limiting factor and soil needs amelioration. How
about (mostly) only burning the volatiles and saving charcoal for soil
amelioration, to get better crops, with the positive effect:

Some of the carbon could not burn to CO2; and by this there was a lot
retaining of C02 out of the atmosphere, which was just captured from
wood-grow.

By normal natural cycle, the wood was broken down to CO2.

 

Have a good New Year!

 

Martin

 

 
<Dear Stoves,
< 
<Friends working in Darfur asked "What is a good fire" and I thought I'd
forward
<my thoughts to the List as related to discussions of insulating pots, etc.
See
<lots of you at ETHOS next weekend!
 
<In my opinion, a good fire that cooks using the least wood is characterized
by:
< 
<The size of the fire is matched to the job. The job is determined by how
good a
<heat exchanger the pot is. Pots loose heat mostly by evaporation. Losses
<through
<the sides are about 20%, evaporation 80%. Attention paid to deceasing
evaporation
<means a smaller fire, less wood used. Savings during bringing to boil are
less
<but during simmering savings are big.
< 
<Heat gets into the pot mostly through the bottom. We want lots of heat in,
< 
<heat lost. So big bottom, small top. Decreasing the water surface area
<decreases
<evaporation.
< 
<And a lid is very helpful.
< 
<The job of the fire is to bring the water to boil in a time period that
pleases
<the cook (usually fast!) and then if the pot is covered then we need less
than
<1/4 of the energy to simmer. Big fire first, then much smaller fire.
< 
<A well tended open fire takes about 1200 grams of dry (10% moisture
content) wood to
<boil 5 liters of water in a normal straight sided 7 liter pot and simmer
for 45
<minutes. More than half the wood is used to boil.
< 
<The pot can be 5" above the ground over the fire. Sticks should be burned
at the
<tip and pushed
<into the fire as consumed. Folks usually know this. A grate under the fire
<helps
<to keep the fire going. Good to let air under the fire. If a lot of
charcoal is
<made then dirt can be pushed to seal space between pot and outside air,
leaving
<a very small hole to keep the charcoal burning. If the pot is covered it
only
<takes about 80 grams of charcoal to simmer food for 45 minutes.
< 
<Great 3 stone fire makers put a 2" layer of ash under the fire. Insulates
the
<fire.
< 
<For the 5 liters of water in the 7 liter pot high power should be
approximately
<4-6,000 watts. Too big a fire wastes energy. Fire size is dependent on pot
size.
< 
< 
<Using a skirt saves 1/3 of the energy to boil and simmer water.
< 
<Unfortunately a fire that is 1,000W to 1,500W can only be made with really
<small
<sized wood, like 3/8" or so, and it requires constant tending. Bigger
sticks go
<out. So cooks tend to
<make much bigger fires for simmering than necessary because the wood is too
<big.
<Wastes wood.
 
<I think that these are the highlights...probably missed some. 
< 
<Best,
< 
<Dean