[Stoves] Cajun Rocket Pot

[Crispin Pemberton-Pigott]

Dear Todd

 

In this photo it appears there is a drop-down hood or door that closes off
the excess primary air that would normally enter through the fuel hole.

 

http://www.silverfire.us/page_10_1/silverfire-survivor

 

Is there some side wall or baffle that assists this?

 

Do you provide secondary air through other holes inside the stove? It is
mentioned but not shown.

 

Have you measured the typical excess air level above the combustion chamber
for a typical test?

 

I am interested in knowing how you calculated the thermal efficiency. You
mean the fire-heat to pot-heat transfer efficiency, right?

 

Thanks
Crispin

 

+++++++

 

Subject:  Cajun Rocket Pot / TLUD Soot

 

Soot is an end product on all pots used on biomass stoves with or without
fins or skirts.  Heat transfer is increased by adding more surface area to
cooking pots with dowels, finned ribs, corrugated ribs, rows of fins or full
skirted pots as discussed.  Steel woks with lamented cast iron bases with
fins have been available in China for quite sometime.  We have both in our
SilverFire showroom.   They are designed specifically for biomass.  Finned
pots specific for LPG have also been available for a number of years.

 The Chinese Enron turbo pots have been marketed in the USA for several
years (www.turbopot.com <http://www.turbopot.com> ).   Rebates for Enron
finned pots are available from utility companies in the USA for LPG savings.
The LPG fin design on Turbo pots differ significantly from the biomass
design.  Narrow LPG finned pot channels clog with soot and the end result is
that the soot negates heat transfer, if used with biomass.  Fin designs for
biomass cooking are significantly wider and work well.  Time to boil is
significantly reduced.

 The ease of cleaning and product acceptance is also important, as Dale
touched upon.  We had early prototypes of both fin pot & skirted pots
fabricated in 2008.  I was not a proponent of the Aprovecho fin pot.  It
made no sense for the end user.  The early design had fins that extended
from the base and up the sidewalls of the pot.  We would have had to provide
tetanus shots for end users, had that design ever reached the market.  The
exterior design was unacceptable.  Cleaning or handling the pot was a
handling hazard. 

 Our production pot we introduced to the introduced to the market was the
skirted pot.  It cut approximately 5 minutes to time to boil in our early
WBT work.  I brought the skirted pot to market though, for the important
fact that we designed the skirt to protrude below the cast iron cook top.
This important design feature reduced the chance of the pot sliding off the
stove to prevent burning the cook or children.  Since soot did not
accumulate on the exterior skirt, it also meant less cleaning for the cook,
compared to the finned pot.  The skirted pot was more acceptable than our
fin pot design.  Combining a skirt and fins would provide even greater heat
transfer.  A well-designed pot must be easy to clean.   

 Todd Albi, SilverFire  

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