and powering engines. However, it is important to note that combustion can also release pollutants and contribute to environmental issues such as air pollution and climate change when not properly controlled or when dirty fuels are burned. Whilst the combustion requires an ignition source to initiate the chemical reaction between the fuel and oxygen, if the fuel and oxygen are present, the combustion process becomes self-sustaining. Combustion reactions can be complete or incomplete.
Complete combustion A complete combustion reaction occurs when a fuel combines with oxygen (O 2 ) in the presence of a flame or sufficient heat. This reaction results in the formation of carbon dioxide (CO 2 ) and water (H 2 O) as the primary products. Here is an example of the complete combustion of methane (CH 4 ):
CH 4 + 2 O 2 → CO 2 + 2 H 2 O Incomplete combustion
Incomplete combustion occurs when there is insufficient oxygen during the burning process. As a result, the fuel does not completely react with oxygen, leading to the formation of products other than carbon dioxide and water. Incomplete combustion usually produces carbon monoxide (CO) and water (H 2 O), along with other byproducts such as carbon (C) or soot. Here is an example of incomplete combustion of methane: 2 CH 4 + 3 O 2 → 2 CO + 4 H 2 O In this case, carbon monoxide (CO) is formed instead of carbon dioxide (CO 2 ) due to the limited availability of oxygen. Methods of heat transfer Fire and smoke can easily and quickly spread through buildings and neighbouring properties if it is not quickly controlled. The spread of fire is reliant upon the following methods:
• Conduction. • Convection. • Radiation. • Direct Burning.
Conduction This can occur in solids, liquids, or gases, although it is more common in solids. Thermal conductivity, the ability to conduct heat, varies between materials. Most metals conduct heat relatively easily and are classed as good conductors. Steel conducts heat very well. A steel girder passing through a structure may conduct enough heat through to a connecting room, thus spreading the fire to other rooms.
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