On January 14, ARC staff experienced a catastrophe when ice brought down about one third of the trees in our valley and we had no electrical power for seven days. Depending on the grid for heat and light is great when everything works. However, when the lights go out, a warm house becomes really important. […]
Heat can constantly leak out of older homes. Photo: Gina Sanders Aprovecho is investigating how to design and manufacture biomass-heating stoves that protect health and climate when burning renewably harvested biomass. Of course, staying warm depends on many factors including how much energy is being leaked from the building. Net-zero buildings are usually tight and […]
Since 2012, optimized biomass cook stoves have been tested at ~50% thermal efficiency The temperature of the hot gases flowing past the surface of the pot is increased by In convective heat transfer, the primary resistance is the surface boundary layer of still air immediately adjacent to a wall. Increasing Temperatures, increasing exposed Area, increasing […]
Key findings compared with the 3-stone fire:
In 2014, the World Health Organization (WHO) issued the first-ever health-based guidelines on clean fuels and technologies for household cooking, heating and lighting: INDOOR AIR QUALITY GUIDELINES: HOUSEHOLD FUEL COMBUSTION 2014 From section 5.4.1 Roles of clean fuels and lower emission solid fuel stoves “As recognized in these guidelines, and specifically in Recommendation 2, which addresses policy […]
Regardless of the velocity of secondary air, flow rate, or the angle at which air is injected into the fire, secondary air tends to lower the temperature of gases. Researchers have found that injecting secondary air into the side of the flame in a Rocket stove results in most effective mixing.* The Jet-Flame, on the […]
If protecting health and climate are important in stove projects, why not monetize the reductions of health/climate pollutants in carbon-offset projects? Only the reduction in fuel use earns carbon income now! With equal heat transfer efficiency, dirty burning stoves earn as much as clean burning stoves. Dirty burning stoves are less expensive. “Market demand” reinforces the use […]
Champion (2021) average energy emission factors (g/MJ) from ISO high, medium, and low tests. Lab testing can quickly compare emissions from stoves. The EPA and ARC labs now measure the climate emission factors, not just PM2.5 and CO. It has been proven that only field tests show real world performance. Together, lab and field tests help […]
Primary air usually controls the rate of reactions: How fast the solid biomass changes into wood gas. Jets of primary air into the charcoal beneath the biomass add mixing while raising temperatures. Secondary air jets into the side of the flame can also supply needed mixing but tend to lower temperatures. Metering the gas supply […]
Dr. Sam Baldwin describes the use of a pot skirt in his book “Biomass Stoves: Engineering Design, Development, and Dissemination (1987).” Changes in the length and diameter of the channel gap (between the pot and the interior of the skirt) result in dramatic changes in heat transfer efficiency. “In fact, the channel efficiency, defined as […]