combustion and fuel

COMBUSTION AND FUEL

Performance Task

You and your group will be given a source of energy and have to convince the Department of Energy of the Philippines that your source is the best to power the Philippines into the future. But first we must understand how fuels burn, and their effects on the planet.

Fuels react with oxygen to release energy.

Complete combustion happens in a plentiful supply of air.

Incomplete combustion occurs when the supply of air is limited.

Complete combustion releases more energy than incomplete combustion.

Incomplete combustion also creates carbon monoxide, and more soot. Which we saw in the lab.

Combustion

Fuels are substances that react with oxygen to release useful energy. Most of the energy is released as heat, but light energy is also released.

About 21 per cent of the air is oxygen. When a fuel burns in plenty of air, it receives enough oxygen for complete combustion.

Fuels such as natural gas and petrol contain hydrocarbons.

The fuels such as isopropanol, ethanol and the other fuels from the lab also contain these hydrocarbons.

Methanol- CH40Ethanol- C2H60Propanol- C3H80Butanol- C4H10O

Complete Combustion

In general for complete combustion:hydrocarbon + oxygen    →    carbon dioxide + water

Complete combustion needs a plentiful supply of air so that the elements in the fuel react fully with oxygen.

When these fuels burn completely it’s known as complete combustion

Incomplete combustion occurs when the supply of air or oxygen is poor.

Water is still produced, but carbon monoxide and carbon are produced instead of carbon dioxide.

In general for incomplete combustion:hydrocarbon + oxygen    →    carbon monoxide + carbon + water

The carbon is released as soot. Carbon monoxide is a poisonous gas, which is one reason why complete combustion is preferred to incomplete combustion.

Gas fires and boilers must be serviced regularly to ensure they do not produce carbon monoxide.

Incomplete Combustion

Bunsen Burner

The Bunsen Burner uses methane CH4 as its fuel which is a hydrocarbon

The air hole allows for complete or incomplete combustion to occur.

methane + oxygen    →    carbon dioxide + water

When the air hole is opened fully a blue flame is produced, and complete combustion occurs.

A very hot, blue flame is produced.

Air hole closedWhen the air hole is closed the natural gas can only mix with air at the mouth of the chimney. Incomplete combustion occurs as a result:

methane + oxygen    →    carbon monoxide + carbon + water

The yellow flame is often called the safety flame

A yellow flame is produced, which transfers less heat energy than the blue flame. The yellow flame is brighter than the blue flame because the specks of carbon glow when heated.

GREENHOUSE EFFECT

http://www.youtube.com/watch?v=dP-tg4atr5M

ATMOSPHERE GASES

GREENHOUSE GASESExcluding water Vapor which can be up to 40%