10-08-2012, 12:59 PM
Emission Control
Emission control.pptx (Size: 1.36 MB / Downloads: 44)
Hydrocarbons (HC)
Resulting from the release of unburned fuel into the atmosphere.
Produced by incomplete combustion or by fuel evaporation.
Mostly related to ignition problems.
Effect could be eye, throat, and lung irritation, and, possibly cancer.
Carbon Monoxide (CO)
Extremely toxic emission resulting from the release of partially
burned fuel (incomplete combustion of petroleum-based fuel).
CO prevents human blood cells from carrying oxygen to body tissue.
Symptoms are headaches, nausea, blurred vision, and fatigue.
A rich air-fuel would increase CO; lean air-fuel mixture would lower
CO emissions.
Engine Modification Related to Emission Control
Lower Compression Ratios
Use of unleaded gasoline that permits use of catalytic converters and burns
completely to lower HC emissions.
Lower combustion temperature = Lower NOx emissions.
Smaller Combustion Chamber Surface Volume
Reduce HC emissions.
Lowers the amount of heat dissipation out of the fuel mixture.
Reduce the chance of fuel condensation.
Reduce Quench Areas in the Combustion Chambers
Lower HC and CO emissions.
Quench areas- movement of piston too close to the cylinder head.
If too close, it tends to quench (put out) combustion and increase emissions
due to unburned fuel.
Types of Converters
Three-way Catalytic Converter reduces HC, CO & NOx (Platinum and Rhodium).
Dual-bed Catalytic Converter normally has both a three-way (reduction) and a
two-way (oxidation) catalyst.
Mixing chamber is provided between the two.
Air is forced into the mixing chamber to help burn the HC and CO emissions.