[Stoves] Re: New Handbook for Biomass Cookstove Research, Design, and Development

Stovers,    (and placed on the   ePosts   at the  www.drtlud.com  website for easy access and wider audiences)

This new publication is definitely worth some of your time to download (free), save, and look at (at least scroll through and “read at your degree of interest”).   Good diagrams, and very nice summaries of the issues of stove R&D and design. 

Download the full handbook here: http://cleancookstoves.org/resources/517.html

Of course I focused on the TLUD issues. 
1.  No glaring errors were noted.  (Opps, one is noted when I wrote the content below). 

2.  There were some understatements that have background stories that would be too detailed for this publication.
Example is on Page# 22 (22 of 36 digital sheets).

Users of batch-fueled cookstoves like TLUDs often wish to continue cooking after the initial fuel
batch has burned out. Adding new fuel to the stove causes it to switch from operating in a TLUD
mode to a conventional updraft gasifier mode (Figure 15).

That part is true.  But then it goes on about Tryner’s work at CSU with observed difficulties (correct) but does not say that that research put in a substantial amount of new fuel all at one time (a major cause of the difficulties).  

The continuing paragraph refers to Aprovecho results with a  TLUD-FA stove (incorrectly reference to the Reed-Larson 1996 article about TLUD-ND stoves)  and states that performace is not compromised when:

the user can meter in additional fuel through the door in a low-power operating mode.

Sorry, but in my opinion, there are serious compromises (some increase in emissions including when each new amount of fuel hits the top of the charcoal bed and shortening the stove life because of high temperatures from air directly blowing on hot charcoal in the bottom).  Therefore, this refueling is NOT good advice.   So, I would say that this is a glaring error that unfortunately will be repeated over and over, with citation to this publication.   But that is only my opinion.

3.  A few missed opportunities to make more complete statements:
    Example:  Page # 32 (34 of 36 digital sheets):

To achieve more turbulent flow without a fan, natural-draft cookstove designers have added features
to the interior geometry that suddenly change the flow path and create turbulence in local
mixing zones.

Very true.   Then comes the example with a side-feed stick-burner stove (rocket type, but not showing the rocket fuel shelf;  in fact, I do  not recall seeing a full discussion of the true Rocket innovation by Winearski to have the air entering under the burning tips of the sticks).

For example, the Envirofit G-3300 has a choke ring, like a large metal washer, in the riser. The
choke ring disturbs the flow of air and combustion gases and generates a local mixing zone
(Figure 20) (DeFoort et al., 2010.

Then there is reference to Natural Draft TLUDs, but only the stationary vane that were pioneered by Kirk Harris (not mentioned) and attributed to Aprovecho.

What was not mentioned is the “concentrator”  (disk or plate) that does precisely the same thing as does a “choke ring”and it is the
fundamental innovation of Wendelbo’s Peko Pe TLUD (1990s) and Anderson’s Champion TLUD (2005). 
I hope that others will send comments about this publication that is worthy of wide consideration by all “Stovers”.