A boundary layer of still air on the bottom and sides of a pot keeps the hot gases from actually contacting the surface and is a dominant factor in heat transfer efficiency. According to Newton’s Law, doubling the surface area doubles the heat transfer when the temperature and velocity of the gases are constant. In […]
When a wooden stick is burned a lot of smoke is produced but the made charcoal at the tip of the wooden stick does not make much smoke.Rocket Stove: Push the sticks in slowly so the charcoal at the tip is burning.TLUD: Charcoal covers the slowly burning fresh wood. If the stove begins smoking, the solid wood […]
Almost 20 years ago, ARC was invited to a conference in Bonn, Germany to consider standards for cook stoves including emissions. In preparation, we met with Dr. Kirk Smith and his protégés at the University of California at Berkeley. We discussed the beneficial effect of increased air exchanges that decrease the concentrations of CO and […]
Forced draft mixing with preheated jets of primary air reduced emissions of PM 2.5 by around 90% in our stove tests with the Jet-Flame. Would adding secondary air jets further decrease emissions? Secondary Air Works in TLUDs Lefebvre, Vanormelingen, and Udesen examined secondary air jets air in cylindrical combustion chambers and describe most successful patterns […]
The ARC lab is located in the Oregon woods where “hippies” and “rednecks” live on small farms in approximately equal numbers and share numerous points of view. I learned about these overlapping values when I accompanied my Dad, a Christian community organizer, to pot-luck meetings at nearby Granges, members of a farmers’ association organized in […]
The direct burning of biomass seems to be dramatically more efficient compared to ethanol for applications such as home heating, cooking, heating water, or drying clothes. It makes sense that not having to create alcohol from biomass would save energy. When the use of natural gas is decreased (due to climate change), burning biomass for […]
Cooking outside When the air exchange rate is doubled, the concentration of smoke is reduced by half. The average house in low middle income countries is estimated to have around 12 air exchanges per hour (ISO 19867-3). When ARC measured the air exchange rate outdoors in a gentle breeze it was found to be about […]
There are at least three ways to make institutional stoves with chimneys, all of which work well and save fuel and decrease emissions. Here they are: Shell Foundation supported the making of an eight-part video, a step by step guide to making a 50 to 100 liter institutional Rocket stove, with a heat resistant metal […]
by Kirk Harris Blade cross sectional shapes: There are several main physical principles that can be used to make a functional cross-sectional shape. The gas enters the stationary fan vertically from below, and should leave the fan at as flat an angle as possible. Deflection: The side of the blade that faces the oncoming gas […]
learnmech.com/importance-of-turbulence-swirl-squish-tumble-related-to-ci-engine Turbulence is very important for close to complete combustion. Swirl, Squish, and Tumble are used to create turbulence in internal combustion engines. Kirk Harris discovered that a static fan shape with overlapping 70 degree blades creates lots of fast moving swirl at the approximately one to two meter per second velocities found in TLUDs. […]