[Stoves] Stoves in China

[Crispin Pemberton-Pigott]

Dear Paul

I think it is important that you try the results of a few old stove tests in
the dry fuel equivalent calculator.  Nigel and I tried to accommodate a wide
variety of fuels in the sheet so that you get information that is close to
the truth about the thermal performance of your designs and design changes.

Where there is a significant difference in the moisture content or charcoal
yield, you will see some interesting results.

I am very interested to hear from you what the results are for actual test
data plugged in from gasifiers, and from gasifiers where the charcoal yield
is pretty low.

If you have been using any of the standard tests or have been using the WBT
in its present form, you might try putting in the data to see what the
differences are.

We noticed in particular that the low quality fuels like grass, waste
agricultural materials and rice husks are performing far better than was
thought in terms of thermal efficiency.  Roger Samson and I have been
talking about this and how it affects the CO2 offset value of improved
stoves.  The difference in CO2 emissions are significant if the thermal
performance is not accurately reflected.  He is doing a lot with grass which
has a low heat content.

Version 1.0 of the calculator is for getting the basics right.  We are going
to put in a second method of determining the heat yielded by the volatiles
which will give accurate results for gasifiers for fuels where the carbon
content of both the raw material and char is known. We tried it and it is OK
but decided to go with the simpler version first for comments.

There is a question you will have to address which is what happens to the
char removed from the gasifier.  If it is 'useful' then it can be counted as
'not burned' but if the resulting char has to be thrown away without
benefit, it can be viewed as having been consumed. We talked about this once
a couple of years ago.

If you are doing a test of a stove development you will be interested in the
total thermal efficiency at certain times and won't worry about the char.
In that case you will find the assessment of total energy offered to the pot
useful because it will tell what the thermal efficiency is when boiling, for
example, and the specific consumption of energy used to simmer, whether
expressed in watts per litre simmered or the dry wood equivalent.

If you are using regular woody biomass you can go with the charcoal heat
value of 29.477 LHV if you are not sure what it is.  When we know more about
the carbon content of char produced at different TLUD temperatures you will
enter the appropriate values.

Good luck!
Crispin

-----Original Message-----
From: stoves-bounces at listserv.repp.org
[mailto:stoves-bounces at listserv.repp.org] On Behalf Of Paul S. Anderson
Sent: October 8, 2007 7:37 AM
To: STOVES - Listserve
Subject: [Stoves] Stoves in China

Stovers,

With Tom Mile's assistance, I have posted a detailed item about a TLUD
gasifier
stove project in China that won an Ashden Award this year.  25,000 TLUDs as
of
several months ago, and headed toward 10,000 units per month.  See the
report
at:                      
http://www.bioenergylists.org/files/TLUD_Gasifier_in_Ashden_Award_for_Enterp
rise_2007-09-19.pdf