[Stoves] Gasifier+charcoal burner, a new stove from Dr Nurhuda

Crispin Pemberton-Pigott crispinpigott at outlook.com
Wed Dec 21 15:12:18 CST 2016


Dear Adam

To turn down a TLUD effectively you have to control both primary and secondary air.

I have a new report that is over the top from Kyrgyzstan about the performance of the crossdraft gasifier low pressure boiler. It uses exactly the same technique which is to have a single control for both air supplies then a design (they are different inside of course) that separates the air proportionately so as to control the burn rate while stabilising the excess air so the burn remains clean.

The KG Model 5 is better at this because it works in a different manner but the principle goal is the same: full control with a single air controller and self-splitting. There are limitations of course, one of which has been overcome by transferring the fuel to a second chamber which can have different ventilation.

The cooking efficiency of a Nurhuda stove (earlier ones I have tests for) at low power is similar to that of a low end propane stove. The only better one I have tested is the Vesto which has down-drafting preheated primary air so it can be very well controlled (66% eff). If that were incorporated in Nurhuda’s latest the turndown could be improved and the efficiency raise yet further. High turndown can only be achieved with a fully lit fuel load of course, not right off the bat.  Things have to be hot.

Regards
Crispin


From: adam at instove.org [mailto:adam at instove.org]
Sent: 21-Dec-16 16:04
To: Crispin Pemberton-Pigott <crispinpigott at outlook.com>; Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org>
Subject: RE: [Stoves] Gasifier+charcoal burner, a new stove from Dr Nurhuda

This is pretty amazing, Crispin.

How does it achieve the turndown?

Adam
-------- Original Message --------
Subject: Re: [Stoves] Gasifier+charcoal burner, a new stove from Dr
Nurhuda
From: Crispin Pemberton-Pigott <crispinpigott at outlook.com<mailto:crispinpigott at outlook.com>>
Date: Wed, December 21, 2016 2:00 pm
To: Discussion of biomass cooking stoves
<stoves at lists.bioenergylists.org<mailto:stoves at lists.bioenergylists.org>>
Dear Friends

I have received some new photos showing Nurhuda’s double fuel stove (char making and char burning) with the charcoal burning phase shown clearly.

The fuel bring transferred to the smaller char-burning fuel chamber:

[cid:image001.jpg at 01D25BA4.FB73F350]



The resulting fire:
[cid:image002.jpg at 01D25BA4.FB73F350]

The pot on the lower rests:
[cid:image003.png at 01D25BA4.FB73F350]

The bottom of the pot after combusting wood pellets then the charcoal:
[cid:image004.jpg at 01D25BA4.FB73F350]

I think this is a great achievement. Starting with a solid wood fuel and ending with a very clean pot. As usual, the stove is quite controllable. Dr Nurhuda’s air control method has always been pretty effective – a turn down ratio of above 4:1.

[cid:image005.png at 01D25BA4.FB73F350]

Regards
Crispin
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