[Stoves] Studies of pressure variations in a TLUD

[Julien Winter]

Hi Chrispin;

The pulsing I observed is with concentrator rings on a 7-inch diameter
TLUD.  The concentrators are about 6 cm above the top level of the pellet
fuel.   The fuel bed is 10 cm deep.   The pulsing occurs with the narrowest
aperture concentrators (25-50% TLUD reactor diameter), from moderately low
to highest primary air, and during the entire gasification until the
ignition front hits the grate, and we start to approach flame-out.

At first I thought that the oscillations may be pressure build-up, below
the concentrator (or nozzle), because the pathways for preheated secondary
air and primary air will have buoyancy and momentum.  The pathways also
have resistance: the secondary air is up a narrow 1/2 inch gap between
concentric cylinders of the TLUD, and the primary air flow faces resistance
at the regulator and in the fuel bed.

I thought that perhaps I was getting some pressure build-up below the
concentrator or nozzle throats, like the inner chamber of a rocket engine.
I was even thinking we should rename TLUDs to 'rocket stoves.'

Then, I lifted the nozzle off the TLUD to create a gap that would allow for
pressure release.  The pulsing was unchanged.

It will be a couple of weeks before I can get a video of the pulsing,
because my gear is doing other duties at the moment.  I will also summarize
my observations, because I recorded the frequency of pulsing for the
different treatments (following Ron Larson's advice).

Cheers,
Julien


-- 
Julien Winter
Cobourg, ON, CANADA
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