[Stoves] stoves and credits again

[Nikhil Desai]

Crispin:

"just use the dry ultimate analysis as the raw data then enter the fuel
moisture to get the current value. "

Please tell me whether, to your knowledge, WBT results as reported in the
last ten years, use "dry ultimate analysis" or keep these values as close
to fixed as possible.

Nikhil



On Fri, Sep 22, 2017 at 8:36 AM, Crispin Pemberton-Pigott <
crispinpigott at outlook.com> wrote:

> Dear Paul
>
> The energy in a fuel can be estimated well using the following formula
>
> HHV (in kJ/g) = 0.3491C + 1.41 H  - 0.1034 O + 0.1005 S - 0.0151 N -
> 0.0211 A
>
> Where  C is the (mass) fraction of carbon, H of hydrogen, O of oxygen, S
> of sulfur, N of nitrogen, A of ash
>
> There are other formulas in use - this one I believe comes from Tom Reed.
>
> The conversion from HHV to LHV is standard and well known, accounting for
> water vapour generated by burning the hydrogen.
> The compensation for moisture content is also well known involving a
> subtraction for the mass of water and then for heating and evaporating that
> moisture.
>
> So using the above formula only you can get a pretty good estimate of the
> energy content of a wood or char fuel.
>
> I developed a spreadsheet for determining the energy released during
> various portions of a Water Boiling Test to see how the assumption that the
> moisture left the fuel 'constantly' compared with the assumption that the
> fuel dried first and burned later. It is attached, and it uses the above
> formula.
>
> You can enter fuels of your choice and burn and water loss choices to see
> how the energy released by the fire is accounted.
>
> To use it, put in the dry fuel analysis, for example the Douglas Fir is
> entered in row 13. The moisture is entered in cell E12. That will calculate
> the wet basis ultimate analysis in row 12.
>
> Do the same for the char remaining at the end in rows 15 and 16.
>
> Rows 18-24 are the calculations provided by the WBT, at that time the UCB
> WBT 3.1 (uncorrected, maybe?).
> Rows 28-32 are the calculations proposed where the fuel evolves during the
> burn. The point was to compare the energy released values on the right. The
> heat released calculation error is posted on the far right, in all cases
> the WBT over-estimates the energy released during a section of the test.
>
> In the upper section the LHV is given for both the dry and moist fuels on
> a per kg basis.
>
> You can enter any fuel, liquid or solid, just use the dry ultimate
> analysis as the raw data then enter the fuel moisture to get the current
> value. For ethanol and kerosene there might be no moisture at all.
>
> Regards
> Crispin
>
>
>
>
>
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