[Stoves] Vegetable oils

[Richard Stanley]

Crispin Pete et al. ,

Several in Malawi were dipping the agro residue based briquette in said veggie oils. Kobus experimented with same too. 
As I recall,  It provided a quick start and readily efficient self-consuming/ hcleaning/  wicking system for the oil during combustion. Very little is needed something like 1 or 2 ccs per a 10cm ø x 7.4cm tall, hollow core (~ 550 cc/~140 gram) briquette.  

Richard Stanley 


On Nov 28, 2011, at 9:00 PM, Crispin Pemberton-Pigott wrote:

> Dear Peter
>  
> Good to hear from you, I was thinking of you last week testing a downdraft stove using chunks of wood the same size you use on your DD BBQ (barbie). The chunks of wood provide quite a bit of excess air so the way the heat transfer takes place it affected a lot.
>  
> >As far as I know the difference between kerosene (paraffin) and higher hydrocarbon fractions, including vegetable oils is the fact that they are not distillable under atmospheric pressure.
> The stove must work then by boiling something in the veggie oil that boils at a temperature achievable in the evaporator tube. Perhaps that is why there is so much gunk left behind. A completely different approach (and an old one) is dripping oil onto a flat plate that is completely contained inside the combustion chamber. People burn old engine oil that way, and for similar reasons.
> >Undistillable hydrocarbons are fed into the fire as a spray of very fine droplets that burn completely.
> With the residence time in the flame matching the burnabilty of the droplet, right? When a droplet of diesel burns, has it been evaporated by radiant heat under that increasing pressure of the pressure wave?
> The same could be done with vegetable oils at the combustor end. However, most vegetable oils tend to react slowly with oxygen to form gunk which eventually blocks the passages it has to flow through.
> Is this process dramatically accelerated by heating the oil? In other words, is the depositing cause by O2 already in the fuel? That bodes badly for the future of burning raw oil.
> So for a stove that burns vegetable oil, the piping from the storage to the burner should be of very simple shape and easy to clean.
> Daily, as I understand it.
> Realising that producing a spray of fine droplets is out of the question for domestic stoves, we have to find something that feeds the oil to the combustion zone where the carbon, resulting from the decomposition of the oil is burnt as well.
> How about using one of those spinning disks with a spiky periphery that are used in greenhouses to make as fine a mist as possible? They are very small (50-75mm) and use only a small amount of power. It is conceivable they could be driven by electricity, heat or draft.
> Possibly something like a perforated disk where the oil burns in updraft mode and where the holes occupy a sufficient part of the disk area that all the char comes in contact with air.
> Good idea. A variation on the drop-onto-plate idea might do.
> Does the Protos stove have any relation to Siemens.
> Yes it is a Bosch-Siemens product.
> Regards
> Crispin
>  
> _______________________________________________
> Stoves mailing list
> 
> to Send a Message to the list, use the email address
> stoves at lists.bioenergylists.org
> 
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org
> 
> for more Biomass Cooking Stoves,  News and Information see our web site:
> http://www.bioenergylists.org/
> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20111129/c667bcc6/attachment.html>