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Traditional Three Rock Fire

Definition

The rocket stove has social and environmental benefits to the large population in the developing world that have no other alternative than burring biomass for their cooking and heating needs. Rural cultures around the world depend on the three rock fire for there cooking needs. Inefficient methods of cooking places the environment in jeopardy, over harvesting of fuel for cooking can causes damage to vegetation and wildlife. Understanding traditional cooking methods can help explain why improved fuel stoves are an important appropriate technology. “Most cooking fires are surrounded by three of more stones, bricks, mounds of mud of lumps of fireproof material – thus the common name of three rock fire” (Foley, Moss, and Timberlake 1984).

Benefits

Three rock fires have benefits not found on improved stoves such as; space heating, protection from insects, and the flexibility to use a wide variety of fuels in different seasons. Domestic lighting is one of the important uses of three rock fires, a function that the improved stove cannot perform. “Three rock fires provide light, heat and a social focal point for family and friends” (Foley, Moss, and Timberlake 1984). A three rock fire producing lots of smoke in a riparian or wetland environment might have the added benefit of preventing insect’s bites. The open fire possesses important advantages compared to an improved stove. “It cost nothing and no special materials, tools or skills are needed to construct it” (Foley, Moss, and Timberlake 1984). If the other functions of the three rock fire are not replicated with its replacement then the improved stove is not being judged and evaluated fully. “If the fire is used to provide heat or light at times when cooking is not taking place, then its efficiency can hardly be judged only on the basis of how well it heats pots” (Foley, Moss, and Timberlake 1984).

Critiques

A large population of people in developing nations depend on traditional three rock fires for cooking; this primitive form of cooking negatively impacts the health of people using the stove and the well being of the natural environment. Two billion people use biomass for cooking and heating worldwide. Traditional three rock fires are used inside the persons dwelling, usually located on a dirt floor. “Over the last 30 years awareness of the environmental and social costs of using traditional fuels and stoves has grown” (Bryden et al. 2001). Traditional three rock fires pose major obstacles to the environmental, social health and sustainability of society. The most important concern with traditional three rock fires is indoor air quality. Biomass fuels release large amounts of air pollutants when burned on traditional three rock fires. These pollutants become concentrated in inadequately ventilated homes and dwellings. “Several recent studies have identified prolonged exposure to biomass smoke as a significant cause of human health problems” (Barnes 1994). Biomass burned on three rock fires produces harmful soot and ash that become concentrated when confined inside a dwelling, resulting in harmful indoor air conditions. “According to recent estimates by the World Health Organization, up to 1.6 million women and children die every year from breathing polluted air in their homes” (Witt, Weyer, and Manning 2006). Respiratory and vision problems occur in mostly women and children because they spend significant time indoors tending to cooking fires. Another critique with traditional wood fires is the inefficiency in fuel consumption. Traditional wood fires are very efficient at turning wood into energy. However, traditional wood fires are inefficient at transferring the released energy into the cooking vessel. Most of the released energy in the wood is wasted heating the surrounding air rather than heating the cooking vessel. The inefficient transfer of energy requires the user to use more wood fuel, increasing the amount of wood harvested from the surrounding environment. The increased demand for wood can further deplete the already stressed local natural environment. The third critique of traditional wood fires is childhood burns. “Burns are quite common in homes using fire and can be fatal or horribly disfiguring” (Bryden et al. 2001). Children can easily fall into the fire because traditional wood fires are located on the floor. Burns disfigure and scar their victim and the experience can be very painful for both the child and family.

Indoor Air Quality

Indoor air quality is the main driving factor in the decimation programs around the developing third world. Soot and ash produced when cooking with traditional three rock fires creates unhealthy amounts of indoor air particulates, resulting in respiratory and breathing issues.

Fuel Savings

Improved Fuel stoves can reduce the amount of wood fuel needed to cook. Improving the heat transfer efficiency of energy from the fire to the cooking vessel reduces the amount of energy wasted, thus reducing the amount of wood needed. Reduction in the amount of wood fuel needed each month allows the rural family to either save time and money. Rural families who traditionally purchased wood fuel will save money allowing funds to be spent on other basic needs. In Rural cultures that physically find and collect wood fuel, the rocket stove will allow women who predominately collect wood to save time.

Burns

Traditional open three rock fires are dangerous to small children who can easily fall or trip into a open fire on the floor of there dwelling. Improved Fuel stoves are insulated and elevated above the ground, preventing children from accidentally burning them selfs.

Why Improved Fuel Stove are Good

Introduction

A rocket stove is a type of improved biomass stove. Improved stoves reduce the demand for biomass fuel and improve living conditions for populations who currently use three rock fires. The main justifications for improved stoves are economical, social, and environmental. Stove programs can produce economic benefits. The stove saves time and money for the users. In urban areas, were people purchase biomass fuel, the payback time for the cost of a improved stove is short, thus providing extra cash from purchasing less fuel. “In rural areas, more efficient stove can reduce the time spent collecting fuel for cooking, freeing time for child care and income-producing activities” (Barnes 1994). Improved stoves can help moderate the environmental externalities of over harvesting trees.

Improved Combustion

An increase in cooking stove efficiency will bring benefits to the stove user and the natural environment; the reduction of fuel used saves time and money for stove users and prevents rapid depletion of natural fuel sources. Improved fuel stoves improve fuel combustion that reduces the dangerous air pollutants generated when burning wood. The addition of chimneys to improved fuel further improves the indoor air quality.

Improved Transfer of Heat

Improved fuel stoves are designed to be efficient at the transfer of heat from the fire to the cooking vessel. Improved transfer of heat is the key process in there ability to reduce wood fuel use.

Lit Review

World bank paper

Aprovacho

Design

Materials

Budget

Construction Steps

1. We built our combustion chamber out of insulative bricks. The bricks were extensively shaped using a hack saw. Heat resistant putty was used as sealant.
2. We built a case for the combustion chamber to sit in using sheet metal. The metal was cut out with tin snips and bent with square pliers.
3. We used a grinder to cut a square out of the barrel corresponding to the dimensions of the metal casing. The casing for the combustion chamber fits into the hole, protruding on both sides.
4. The casing is firmly secured to the barrel by metal brackets and screws. The combustion chamber slides into the casing which is secured to the barrel. The chamber is now opperational for burning wood fuel.
5. Vermiculite is poured into the barrel in order to insulate the combustion chamber. This insulation fills the space between the chamber and the barrel and is filled as high as the top of the chamber.
6. At the top opening of the combustion chamber we constructed a metal shelf. This shelf is circular and perfectly fits inside of the barrel. It has a square cut in it corresponding to the top opening of the combustion chamber. This allows for gasses to pass through, but seals them off from the bottom half of the barrel. The shelf is secured firmly to the outside of the barrel with L brackets and screws.
7. In the top half of the barrel, we constructed a skirt. This skirt surrounds the cooking pot, leaving a small gap on the bottom and the sides. The skirt was constructed out of a can. We used a grinder to cut a square opening in the bottom to chanel the hot gasses. The top of the can was made completely open. This skirt is fastened to the shelf with screws and washers. The washers provide a resting area for the pot, creating gap between the bottom of the skirt and the bottom of the pot.
8. The pot is inserted into an opening in the top of the barrel. Here we have cut out a circle with the grinder and then carefully bent the metal down at a right angle using square pliers and a mallet This way the pot is extra sealed and the opening for it is not jagged or sharp.
9. We cut a hole out of the upper side of the barrel and fastened a circular metal chimney over the hole using screws.
10. To use our rocket stove, burn fuel inside the combusion chamber and set the pot inside the skirt.

Design Principles

1. A well constructed rocket stove will allow for air to circulate. With this in mind, it is important to provide an even pathway for the air. The chimny, the combustion chamber and the skirt gap should all have the same cross-sectional area.
2. Unless oxygen is being circulated, the fire will smother. When building the combustion chamber it is necessary to provide a shelf for the fuel. This way, fresh air will be pulled underneath the burning fuel.
3. The chimny should be short, reaching just above the cookpot. This allows for hot gasses to flow more rapidly through the system.
4. Heat will radiate from the combustion chamber. For imporved efficiency, insulate arround the chamber.

Testing

Types of Testing

Results

Conclusion

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