Entries by Kim Still

Metering, Mixing, Temperature, Time

Here are lessons learned that summarize what we consider to be the ‘state of the art’ in 2021. Please remember that, as scientists, we do not consider these hypotheses to be true. The concepts are evolving and, like all knowledge, will coalesce into a state of greater accuracy as experience, experiment, and analysis shapes understanding. […]

Primary Air Jets

Champion Forge, circa 1920 The blacksmith’s forge is probably the most familiar technology that blows jets of primary air up into charcoal or coal, resulting in the high temperatures needed to shape or melt metals. A forge needs air at high pressure (10” water column) to do its work. A fan (usually a radial pressure […]

Smoke In The Air!

pdf available at: deohs.washington.edu/sites/default/files/AirFilterInfographic_FINAL.pdf I hope that you are living in a smoke free environment! There’s a forest fire about 40 miles east of the lab that floods our valley with smoke when the wind slows down. I just looked up and noticed that it was getting hard to see Blue Mountain, a sure sign […]

Charcoal Stoves: Ups and Downs!

Ryan Thompson and Sam Bentson spent a year exploring charcoal burning Ken Newcombe and C-Quest Capital have seen firsthand how charcoal production has wiped out forests in Africa. Making charcoal is a very energy inefficient process (Aprovecho Institute, 1984a). Burning off the volatile compounds in wood consumes and wastes between 50% and 80% of the […]

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Remembering Dr. Larry Winiarski

Dr. Larry Winiarski, 1940-2021 Dr. Larry Winiarski, the Technical Director of Aprovecho Research Center (ARC), died this past week at the age of 81. In the 1980’s and 90’s, Dr. Sam Baldwin defined how to improve heat transfer efficiency in biomass cook stoves (pot skirts, etc.), Dr. Tom Reed created the TLUD, and Dr. Winiarski […]

Meeting the World Health Organization Emission Rate Targets

Reducing/removing smoke from the kitchen improves health. Adding a chimney is one recommended solution. In 2014, the World Health Organization (WHO) published intermediate and final indoor air guidelines for vented and unvented biomass cooking stoves. Their strong recommendation directed governments and implementers to advocate technologies and fuels that are proven to protect health. The WHO […]


Product Development

General Manager Sam Bentsen is happy about some LEMS test results. Why test a stove? Most of the time, our lab uses testing for product development. If we did not test a stove prototype we would be guessing whether it met expectations. Testing in the lab gets us ready for the field testing of prototypes. […]

The Oorja Forced Draft TLUD: A Different Approach

Testing the Oorja Stove under the LEMS hood. There are many forced draft TLUDs that are quite similar to Dr. Tom Reed’s 2001 version, the WoodGas stove. The Oorja stove can be about as clean burning but has several obvious differences: a high mass refractory ceramic combustion chamber, much bigger secondary air holes, and high […]