[Stoves] Dry Fuel Equivalent Calculator

[Crispin Pemberton-Pigott]

See http://www.bioenergylists.org/en/crispindryfuelcalc

 

 

Dear Stoves Testers

 

I have sent to Tom Miles for posting, the Dry Fuel Equivalent Calculator
drawn up for evaluation by our list readers.

 

There are 4 pages to the spreadsheet.  The first is where a test result can
be entered.  If you only know the mass of damp fuel burned, the amount of
charcoal remaining and the moisture content of the fuel, it should be
sufficient.

 

Select a suitable dry fuel heat content from the chart on the right if you
don't know the figure exactly.

 

The first set of numbers is the actual heat value of the fuel that was
offered to the pot.  The second sheet is the heat value as calculated by the
UCB-WBT method.  The Dry Wood Equivalent figure in the UCB-WBT is not used
(as previously discussed), but a different formula which can be seen in
their spreadsheet by clicking on the cell.

 

The difference between the two output figures is calculated on the third
page.

 

The fourth page is the two methods plotted in two different manners, the
actual value of dry fuel equivalent against the UCB-WTB for a range of
moisture and charcoal remaining, both as a % of wet fuel burned, then the
relative value of the outputs.

 

You will notice, playing with the numbers, that when the heat value of the
fuel is more than about 20 MJ/Kg the dry fuel equivalent has been
under-reported by the UCB-WBT. Conversely, when the actual heat in the fuel
is less than 20, that method over-reports the heat yielded giving the
impression that the stove has not performed as well as it actually did.  In
the case of a fuel like rice hulls, the difference is significant. Note that
the charcoal heat content should be changed for the rice hulls - see the
small chart on the right of page 1.

 

As always, please look for errors in the calculations.  Sorry about the
formatting of the graphs - the cells with no or very high plus or minus
values get plotted as zero, mostly in order to make the lower moisture
calculations more readable.

 

Best regards

Crispin and Nigel Pemberton-Pigott

Waterloo

Ontario