Question

Automobile air pollution and its control

Answer 1

i. Engine efficiency has been steadily improved with improved engine design.

ii. One of the first-developed exhaust emission control systems is secondary air injection. Originally, this system was used to inject air into the engine’s exhaust ports to provide oxygen so unburned and partially-burned hydrocarbons in the exhaust would finish burning.

Air injection is now used to support the catalytic converters oxidation reaction, and to reduce emissions when an engine is started from cold. After a cold start, an engine needs a fuel-air mixture richer than what it needs at operating temperature, and the catalytic converter does not function efficiently until it has reached its own operating temperature.

The air injected upstream of the converter supports combustion in the exhaust head pipe, which speeds catalyst warm up and reduces the amount of unburned hydrocarbon emitted from the tailpipe.

iii. Converter does not function efficiently until it has reached its own operating temperature. The air injected upstream of the converter supports combustion in the exhaust head pipe, which speeds catalyst warm up and reduces the amount of unburned hydrocarbon emitted from the tailpipe.

iv. The catalytic converter is a device placed in the exhaust pipe, which converts hydrocarbons, carbon monoxide, and NOx into less harmful gases by using a combination of platinum, palladium and rhodium as catalysts.

v. Evaporative emissions control-Emissions are the result of gasoline vapours escaping from the vehicle’s fuel system. In a typical system, vapours from the fuel tank and carburetor bowl vent (on carbureted vehicles) are ducted to canisters containing activated carbon. The vapours are adsorbed within the canister, and during certain engine operational modes fresh air is drawn through the canister, pulling the vapour into the engine, where it is burned.

vii. Reduce use, and car pool.

viii. Monitor and repair any leaks.

ix. Always take used oil, batteries and other fluids to a repair shop for proper disposal.

x. Never allow oil or other toxins to runoff into the ground, street gutters or storm drains.

xi. Take your car to a commercial car wash or use detergents that don’t contain phosphorus to wash your car and direct the flow of runoff to grass clippings or gravel instead of the street.

xii. When purchasing a new automobile look for cars with high fuel efficiency ratings.