[Stoves] stove update

[carefreeland at aol.com]

Crispin, what was the last name of Kevin from Nova Scotia? Has anyone heard from him? Lost his address.  Dan Dimiduk 

On Sunday, March 21, 2021 Crispin Pemberton-Pigott <stoves at lists.bioenergylists.org> wrote:


Dear Krik

>From almost your last sentence:

" This is possibly due to the velocity of the wood gas.  "

I think this is extremely unlikely.  It is due to the buoyancy of the hot gas below.  To induce any meaningful pressure caused by velocity, the gases impacting the restriction would have to be far higher.  If you measure the temperatures (even approximately) at the same points as the pressure readings, you will be able to calculate the draft effect from a difference in temperature.

Only if this fails to explain all the pressures would it be reasonable to look for something involving the inertia of the moving gas.

Before you mentioned a venturi effect.  This is a viable explanation when there is a clear change in gas stream diameter.  The driver is buoyancy, not velocity at these low speeds, but the effect is real.

To create a negative pressure using a change in speed is definitely possible. T do so, use the same rules for creating a Pelton wheel nozzle: take the area of the stove at some point, and divide by 3.  Take the diameter and multiply by 6.  Then make a cone with an entrance area equal to the stove body at that point, that is 6 times taller than the diameter and has 1/3 of the exit area.

This will cause a constant acceleration of gases rising in the cone reaching a velocity that (if vertical) can induce a negative pressure in a larger channel into which it exits.  The purpose of doing this is something like "crop drying" where the air heated over the outside of the stove is either in or drafted into a drying cabinet (such as a tobacco barn).  The exit from the combustor can be used to induce a draft strong enough to power the movement of warmed air out of the building.

Similarly, it can be used to induce a downdrafting fish dryer where the power is supplied by a warm chimney and the dry air is actually the fire emissions mixed with 3-5 times as much volume of ambient air.  There is an SNV Ghana document describing in detail how to build one of these for the production of very-low-PAH soft-smoked fish.

Regards
Crispin


-----Original Message-----
From: Stoves <stoves-bounces at lists.bioenergylists.org> On Behalf Of Harris, Kirk
Sent: Saturday, March 20, 2021 22:56
To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org>
Subject: [Stoves] stove update

All,

Attached is and update of the TLUD stove design I have been working on for several years.

Kirk H.



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