Rocket stoves

What is a rocket stove and how does it function?  (¿Que es y cómo función una estufa de cohete?)  The basic design of a rocket stove was introduced by Dr. Larry Winiarski.  A rocket stove consists of a fuel magazine for wood or other combustible fuels, supported above the entrained air into the flame by a grate or other supporting structure.  A rocket stove also has an internal chimney where the heated flue gases can further react. 

Rocket stoves are one of the primary types of fuel-efficient wood burning stoves in current programs that build and distribute cheap wood burning stoves to developing countries.   Why is a rocket stove more efficient than a normal stove?  (¿Porque es la estufa de cohete mas eficiente de una estufa normal?)

When wood is heated in a basic burning process, organic compounds in the wood gasify and combust with the surrounding air.  This behaves similar to a diffusion flame where the oxygen required for combustion diffuses into the flame from the outside.  If there is not enough oxygen to react with the gasified compounds, then unburned gases will result and appear as soot.  This leads to a loss in flame temperature, and thus lower energy conversion efficiency in the combustion process.  The rocket stove addresses these issues in several ways.  First, because the air enters the combustion process from under the flame, more mixing of the air and the fuel occurs before the flame (primero, la aire entra la proceso de combustion abajo de el fuego, la aire y los combustibles mezclan mas antes de el fuego).  Thus, the flame more closely resembles a premixed flame, which has the potential for a higher combustion temperature and less unburned gases than a diffusion flame if the air/fuel ratio is optimized.  Second, even if unburned gases remain, they can further react in the internal chimney in the rocket stove before heating the pot (segundo, si hay gases que no quemar en el fuego, los gases pueden quemar en la chimenea adentro antes de cambia calor con la olla).  Therefore, a properly designed rocket stove can be very efficient at converting energy to heat with clean combustion (entonces, una estufa de cohete con una deseño inteligente puede cambiar energía y calor muy eficiente y tiene combustion mas limpio).

To improve the cooking ability of the stove, the heat transfer efficiency must also be examined (necesitamos examinar la teoría de cambio de calor para mejorar cómo buen function la estufa).  Both convection and radiation heat transfer are important for a pot directly above the fire (Hay does tipos de cambio de calor que es muy importante por una olla arriba del fuego).  For two or three pot stoves, with a plancha/cooking surface over the internal chimney, the rear burners receive less radiation, and thus convective heat transfer is the predominant energy transfer mechanism (por estufas con dos o thres ollas como una plancha arriba de la chiminea adentro, las ollas segundaria no reciben calor para radiación y entonces conveción es mas importante).  To improve the convective heat transfer coefficient, the flue gas channels under the rear pots can be reduced, or turbulence can be induced, both strategies which have the potential to restrict the airflow and cause there to not be enough air and lead to soot formation.  These are the tradeoffs for stove design (estes es los intercambios para deseño de estufas).  Most of the literature on heat transfer in cook stoves are on single pot stoves, so many improvements are likely possible for plancha-topped multipot burners.