IELTS READING
Traditional cooking stoves: an overview of designs for improving them
1. A large number of people in the world still use wood as the main source of heat for cooking. Many of these people use ‘three stone’ open fires, and although these have the benefit of being very cheap to make, they are inefficient to use. In addition, cooking over an open fire exposes people to wood smoke,
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which irritates their eyes and lungs and makes them susceptible to respiratory diseases. There is also a risk of burns, as the fire has no protection around it. Finally, using wood for cooking contributes to deforestation, in particular around cities and towns, where the concentrated use of wood puts pressure on the surrounding land.
2. Improvements in stove design can bring a number of advantages. Improved stoves allow fuel to burn more efficiently, so getting more heat to the cooking pots, and reducing the amount of wood required to cook a meal. Typically they use between 25% and 60% less wood than open fires. Increased combustion also reduces the amount of smoke that is produced. People save time as they need to collect less firewood – a task which usually falls to women and children. The extra time allows women to take up other activities, including earning extra money, and allows children more time for education. Also, family members are reported to be more willing to help with the cooking once they have a smoke-free place in which to work.
3. There are various levels of improvement which can be made. Efficient wood combustion depends on an adequate supply of air reaching all the areas where the wood is burning. Hot gases tend to rise, creating a draught that draws in more air, so adding a chimney improves this draught. A grate to supply air under the fuel is a second improvement. The next step separates the combustion process from heat transfer to the cooking pots. For example, the ‘Rocket’ stove concept uses a vertical combustion chamber, where the wood burns in air, with a horizontal air and fuel inlet at the bottom. At the top of the combustion chamber, the hot gases are forced to flow through a narrow gap around the cooking pot, so that heat is transferred very efficiently to the pot.