[Stoves] Moisture content in wood - field data

[Tom Miles]

Crispin,

Can you give us a list of species or common names? It's likely that
properties of the fuelwood speices are well documented by World Agroforestry
Center, CFAN, CSIR, SADC and others. 

Thanks

Tom
 

-----Original Message-----
From: stoves-bounces at listserv.repp.org
[mailto:stoves-bounces at listserv.repp.org] On Behalf Of Crispin
Pemberton-Pigott
Sent: Friday, January 19, 2007 4:34 AM
To: Stoves
Cc: David Hancock
Subject: [Stoves] Moisture content in wood - field data

Dear Friends

I have been going over the field data from Swaziland with Simon Mortimore
who did the cooking tests - all of these being large, open fires heating
(mostly) 70 litre cast iron pots.

Because it is impossible to know the moisture content of each piece of wood,
the best we can do is to take samples of each species of wood found in the
pile of wood selected to go into the fire.  This indicates what the likely
moisture content may be (there is a wide variation) but it is difficult to
quantify how much of each species of wood is used in the fire at each site.

Therefore I have calculated an average moisture content for all the wood
from all the sites, trying various things like leaving out the wettest and
driest 10% to see how that affects the final number.

So, taking this into consideration, the average moisture content at
Swaziland orphan care point open fires, sampled in October before the start
of rains, is 15.36% (72 samples).

Casting out the top and bottom 10% gives 13.88% moisture (58 samples)
showing that some are very wet!

Notable is the fact that there is a correlation between sample mass and
moisture content. The heavier the sample, usually, the higher the moisture
content.  Larger wood dries more slowly.  This may indicate that after the
rains get going and the humidity rises, the smaller pieces may not be as
dry.

Simon observes that a significant proportion (up to 30%) of the wood used
has been recently cut from living trees.  Moisture content ran as high as
50% in these samples.  The driest were as low as 5% (small samples, in the
lowveldt, on a hot day).

Regards
Crispin

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