[Stoves] When does a test end?

[psanders at ilstu.edu]

Dear Crispin and all,

Yes, we need to discuss such topics.

No, the quantification of    "when 95% of the combustion portion of  
the fuel has burned"    leaves unanswered questions.  In the TLUDs, we  
run them until about 100% (maybe 98.9%  ;-)   ) of the pyrolytic gases  
are released and consumed.  But there is about 20% by weight (or about  
30% by energy) remaining in the form of charcoal created.

Any testing protocols need to allow for such characteristics.  Why  
stop at 95% and/or why require combustion all the way to 95% ash??

It will be great seeing you in DC in January (and at ETHOS also, I suspect.)

Paul


Quoting Crispin Pemberton-Pigott <crispinpigott at gmail.com>:

> Dear Friends
>
>
>
> Of the age-old questions I when to end a stove test in order to calculate
> the CO and PM emissions (which are the things usually legislated).
>
>
>
> There has been little agreement in different US states and few other
> countries outside Europe have anything at all. Stoves have very different
> burning times, heat generating capacities, fuel loads, burning properties,
> refuelling capabilities and purposes. What can we do that will make
> comparisons fair and possible?
>
>
>
> So, here follows a proposal which seems to work in practise.
>
>
>
> The test is started at the time of ignition.
>
> The test ends when 95% of the combustion portion of the fuel has burned,
> leaving 5%.
>
>
>
> The combustible portion is the non-moisture, non-ash portion of the fuel as
> received (meaning as it is used in the stove).
>
>
>
> When the fuel is weighed, say 5 kg, and either set aside or loaded into the
> stove, the total amount is noted and the moisture content calculated, for
> example at 15% = 750 g. That means there is 4250 g of dry fuel there.  Then
> subtract the ash portion, say it was 3% of the initial mass = 30 g. Final
> number is 4250-30 = 4220. That is the mass of 'things which can burn'. 95%
> of that is 4220 x .95 = 4009 g.
>
>
>
> All the moisture is expected to be gone. So if the whole stove is mounted on
> a scale the mass change will be burnables + moisture = 4009+750 = 4759. One
> the scaled mass has dropped 4759 g the test is over.
>
>
>
> Then the emissions are calculated based on the MJ of heat theoretically
> generated (using LHV as received).
>
>
>
> If a scale is not used, then the mass burned can be determined by weighing
> the fuel as it is use, fuel remaining or anything else that shows when 95%
> of the fuel is gone. Typically this is late in the dying fire stage so it is
> a bit easier then it perhaps sounds.
>
>
>
> When do test a stove that includes refuelling or a number of refuellings,
> the same calculation applies. It seems to work very well, gives results
> representative of real life and normally has a test time that is less than a
> working day.
>
>
>
> It is offered a test method for rating the emissions of any type of testing
> from water boiling to 24/7 space heating.
>
>
>
> Regards
>
> Crispin
>
>
>
>



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