[Stoves] Pressed biofuel - and Fire balls. Testing

[frank]

Hi All,


I am missing some emails because of our server was sending them back.

I believe there is a lot yet to learn regarding optimum air flow for a 
type of fuel and void space. We stovers work at such small scale that 
test methods for coal and other procedures designed for large combustion 
chambers do not apply and we need to develop our own methods.  I think 
the air speed through coal as Crispin mentioned below is just as 
important to biomass fuels.

I agree it would be nice to look at the preheated air as David 
suggested. I am thinking a criss cross pattern air flow might permit the 
air to preheat before it gets to the combustion zone compared to air 
channeled directly up.

Lots of things to try.
I will be at ETHOS with pencil, big eraser and paper.

Frank


David G. LeVine wrote:

> Crispin Pemberton-Pigott wrote:
>
>> Dear Frank
>>
>> We learned from Tom Reed that the superficial velocity (average, as 
>> if there
>> is no fuel) through a combustion bed is a number to watch. There is 
>> in the
>> coal stove a need to track the actual velocity of air through the 
>> pile of
>> fuel because it affects the cooling of the particles (coal lumps) and 
>> how
>> the volatiles are brought to the flame.
>>
>> I was talking to a student yesterday who is interesting in modelling 
>> coal
>> combustion in a CFD project with some others.  There is extremely little
>> work like this going on. At the Univ of JHB we are also going to offer a
>> couple of scholarships for modelling because there is basically 
>> nothing to
>> start working with.
>>
>> The air speed through the voids is going to be very important to the 
>> heat
>> transferred from particle to particle which determines a lot of 
>> things about
>> how coal burns.  The voids and packing density and air velocity are 
>> no doubt
>> going to be as important to wood burners as well.
>>
>> We should sit with a pencil and paper in ETHOS. Are you coming?
>
> Might I be so bold as to suggest that examining the combustion with 
> both ambient and preheated air would make sense?
>
> Given that the preheated air might make the fuel hotter and combust 
> more fully, would it suggest better combustion?
>

-- 
Frank Shields
Soil Control Lab
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