Entries by Kim Still

Turndown Ratio (TDR) in Cooking and Heating Stoves

A cook stove can require a ~three to one turndown ratio to boil quickly and then not burn rice, tomato sauce, etc. High power boils food, ~one third of the high firepower simmers it to completion.  With a lid, even lower amounts of energy can maintain simmering temperatures. When the stove cannot turn down sufficiently […]

South/North Biomass

It has been fascinating to cross-pollinate learnings from biomass cook stoves typical of the Global South and biomass heating stoves used in the Global North. Biomass cook stoves are often used indoors without chimneys. They are not usually closed boxes. Primary air cannot be limited when the fuel door is open. Cook stoves are also […]

ARC Assists CSIR-Ghana in Capacity-Building 

In the first week of October, ARC Research and Development Engineer Jaden Berger visited CSIR-Ghana for capacity building training. The Council for Scientific and Industrial Research (CSIR) is the foremost national science and technology institution in Ghana. The main focus of the visit was to teach them how to perform field testing using various sensor […]

Hardware, Software and Wetware

Hardware includes the physical parts of a computer.  Software is the set of instructions that can be stored and run by the hardware.  Wetware is the people who do things. Of the three, what component makes the most trouble? To what extent do you affect decision making in your circumstances? In stove projects, being adept at […]

Tuning up Health/Climate Heating Stoves and Cook Stoves

“ARC is trying to figure out how to burn wood without making smoke.”  That’s how we sometimes explain our work to visitors.  Folks often say, “That’s not possible!” “How could you do that?” We respond: “It doesn’t seem to be too hard.” “Force the right amount of smoke into the fire for long enough, making […]

Expanding the Three T’s (Again)

A static mixer designed by Kirk Harris Perhaps, Time, Temperature, Turbulence is too easy to remember?   “TTT” is elegant shorthand for how to achieve clean combustion and perhaps other factors are too obvious to mention? At the same time, leaving out other clean burning factors confuses me. Metering the right amount of woodgas into the […]

Working Towards “Zero Green Premium” Stoves

ARC is working on three types of Zero Green Premium biomass heating stoves designed to protect health and climate. “Zero Green Premium” means that the new product costs the same as the dirty one it replaces. As a rough estimate, ARC uses 0.5 grams per hour of PM2.5 at <5% Black Carbon ratio to define […]

Stick Size Matters!

Small sticks make higher temperature gases, better for heat transfer efficiency, but more smoke Monitoring many fires seems to show that along with density, moisture, etc., the diameter of sticks has a large effect on both heat transfer and combustion efficiency.   In a Rocket stove without a closing door, there is obviously a lot of […]

Increased Air Exchange Rate Protects Health

Sunken pot, 50% thermal efficiency cook stove with chimney When (oh, when!) will PM2.5 be included in carbon offset methodologies?  Who can blame stove manufacturers for selling high thermal efficiency/low combustion efficiency stoves when protecting health is not financially rewarded?  Factories can only sell what the market demands even when they manufacture better stoves. Manufacturers, […]

Heat Transfer Efficiency!

Heat Transfer Efficiency! Wow, heat transfer efficiency is easy to understand!  Read on… Raising the Temperature of gases flowing next to the heat exchanger (the pot in a cook stove) is probably the most effective technique in a Rocket stove to increase heat transfer efficiency (use less wood for cooking). Doubling the Temperature of gases […]