[Stoves] Stove comparison coming

[Alex English]

Crispin,
Your familiar categories all reflect how pyrolysis and gasification 
proceed in relation to the air supply. They don't say a lot about the 
continuing combustion reaction downstream. That has a lot to do with 
unburned hydrocarbon particulate and soot.

Are there categories of burners that can suffice as a suffix to the fuel 
dynamic categories, to give a more complete picture?

How easy is it for the untooled or unschooled user to spoil the result 
by getting the secondary air wrong?

Alex



On 3/15/2011 5:19 AM, Crispin Pemberton-Pigott wrote:
> Dear Stovers
>
> We have now performance tests on 17 different stove types at the SEET
> laboratory in Ulaanbaatar, over 50 tests in all. Some were iterations of
> the same stove with changes in operating method and changes it hardware
> but not really different stoves so those count as 1 model.
>
> The result will be coming soon and continue for those interested in
> following it. The stoves fall into the following categories:
>
> Traditional bottom lit updraft
>
> Crossdraft
>
> Top lit updraft
>
> Bottom lit downdraft
>
> They can also be divided into two general groups: those that can be
> refuelled and those that are batch-loaded.
>
> The refuellable ones can be further divided into two sub-groups: those
> that are refuelled periodically and those that have hoppers for
> continuous refuelling.
>
> As time passes we are sure to see original and interesting new products
> that challenge conventional classification.
>
> We have shown that operator technique is not very important for high
> emissions stoves and quite important for low emissions ones. For example
> a badly lit TLUD easily fails the ‘improved stove’ selection criteria
> for funding (a rebated subsidy).
>
> The provisional minimum performance criteria are relative to a local
> stove baseline. It is an emissions per net MegaJoule of heat delivered
> into the home. That means it factors the actual emissions per kg of fuel
> by the thermal efficiency so the actual emissions required to heat and
> cook are used to make the judgement.
>
> The baseline is 650 mg PM2.5/Net MJ and CO is 13.5 g/Net MJ delivered.
>
> Qualifying stoves will emit less than 70 mg PM2.5/NMJ and 7 g CO/NMJ.
>
> There is also a cooking test and they have to be able to run
> continuously 24/7 plus a few other assessments like a 5 year life
> expectancy.
>
> So far at least 5 stoves are in the 99% reduction category. They are not
> similar, including TLUD, BLDD and Cross Draft models. The thermal
> efficiency as a space heater is usually in the 80-85% range. Cost ranges
> from $60 to $250.
>
> One of the more unusual models that popped up last week is a TLUD that
> can be run continuously at full power 24/7.
>
> A large number of interesting figures comes out of the test analysis
> which includes emissions during portions of the test like the ignition
> and dying fire phase. It quickly becomes obvious to the observer that
> start-up emissions account for nearly all the PM emitted by a decent
> coal stove and many of them are net-negative for PM during significant
> portions of the brown coal burn, i.e. they are cleaning the ambient air
> of particulates! Most interesting.
>
> Regards
>
> Crispin in Seoul
>
>
>
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