Child Safety

DT007 3rd Year Assignment – Part 1 2012/13

Automotive Engineering Science (AUSC3000)

1. A hydrocarbon fuel may be designated[pic]. Write the chemical equation for the ideal and complete combustion of this fuel.

Answer:

To find the chemical equation for the ideal and complete combustion of this fuel the following formula must be used:

Formula:

[pic][pic]

Where x = 64, y = 140 & z = 1

Calculation:

[pic]

[pic]

2. List five possible environmental pollutants and / or exhaust emissions that result from the combustion of hydrocarbon fuels in air.

Answer:

The following are five possible pollutants / exhaust emissions that result from combustion of hydrocarbon fuels:

• Nitrogen oxide

• Carbon monoxide

• Benzene

• Nitrogen dioxide

• Water

3. Explain the role played by air – fuel ratio on the levels of carbon monoxide [pic], hydrocarbon gas (HC) and various species of oxides of nitrogen [pic]produced during combustion. Draw a graph oh these changing levels against air – fuel ratio.

Answer:

Carbon Monoxide

CO is a result of incomplete combustion due to insufficient air in the air/fuel mixture. The level of CO emissions (usually measured as a %-age of the total) is almost entirely dependent on the balance of the air/fuel ratio. The lowest emissions being consistent with excess air. In this condition, further weakening the air/fuel ratio has no effect on CO levels. There is too little oxygen available to burn or oxidize the carbon which therefore forms carbon dioxide.

When the mixture is fuel-rich, the CO emissions will be more concentrated.

When the mixture is lean the result is a low reading of carbon monoxide.

Hydrocarbons

Unlike CO emissions, HC emissions increase during both rich and lean air/fuel conditions. When the air/fuel mixture is rich in fuel, the combustion may be...