[Stoves] venturi system -ratios of air and gas? / ND-TLUD

[Frans Peeters]

Julien and all,

 

   The  stove gas output   SPEED of a ND-TLUD is MOST IMPORTANT ! ( 0,3 m/sec is said for a chimney .)

A starting TLUD ,not hot gives “ returning” output gas    due coanda effect  on  a 90° round curved output of ½ the reactor surface .

20/35 cm diameter . 

    BURNING speed regulation  is needed !

Function of the fuel size, fill factor, density, structure  and how dry the fuel is,  

     So we always talk about HALF INFO, without DESIGN measurements !

If the goal is helping Africa ….. We must have open source designs stat covered business .

The OBUNTU GASIFIER stat the never ending WIN 10 stove with 5 passwords to rob the poor …..

 

    Regards

Frans

 

  

 

 

 

 

 

 

 

 

 

 


On Jan 9, 2016, at 7:05 AM, Julien Winter < <mailto:winter.julien at gmail.com> winter.julien at gmail.com> wrote:

Hi folks;

I believe that thorough mixing of secondary air with somewhat (don't know how much yet) more than the stoichiochmetric requirement for oxygen is important for clean-burning wood gas in natural draft burners.  This is because the wood gas is very complex containing fast-reacting H2, CO, CH4 and slower reacting tars.  If oxygen is sufficient, then the fast gases, slow gases, suspended droplets and particles, and secondary products like soot, will oxidize in close proximity.  If oxyen is limited, then fast gases will react, and we loose heat from the site of reaction; heat that would have provide activation energy, and accelerated the reaction rates of the slower species.  

Conservng the heat is important for people who design gas burners that add air in stages.  It is also why I am cautious about adding secondary air through the side-walls of ND-TLUD reactors.  If this isn't done carefully, we end up with unburnt wood gas and products of incomplete combustion that we can't ignite because the reactants are too cold and too dilute. 

For a TLUD, the stoichiometric requirement for secondary air will depend inversely on the rate of primary air, where the combustion begins.  I recall that Mukunda lab in India reported that the ratio of secondary to primary air changed from 6:1 to 3:1 as the rate of forced draft gasification of pellets increased.

Cheers,

Julien


 

 

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