Air Pollution Control Air Pollution Control Devices: Mobile SourcesDevices: Mobile Sources

Automotive EmissionsAutomotive EmissionsM_____ sources contribute approximately 60% of M_____ sources contribute approximately 60% of total air pollution (78% of CO, 47% of NOtotal air pollution (78% of CO, 47% of NOXX, 44% , 44% of total hydrocarbons, 5% of particulates, and 2% of total hydrocarbons, 5% of particulates, and 2% of SOof SOXX

20 to 40% of the automobile's total hydrocarbon 20 to 40% of the automobile's total hydrocarbon emissions are from the crankcase.emissions are from the crankcase.This emission is called b______.This emission is called b______.– function of s___function of s___– after 1963 all vehicles are required to have a after 1963 all vehicles are required to have a

positive crankcase ventilation (PCV) valve positive crankcase ventilation (PCV) valve – the PCV valve opens up more at h_____ speeds to the PCV valve opens up more at h_____ speeds to

allow more crankcase fumes to be sucked into the allow more crankcase fumes to be sucked into the intake manifoldintake manifold

Fuel tank e_______Fuel tank e_______

As the fuel tank warms, the vapors in As the fuel tank warms, the vapors in the headspace are exhausted the headspace are exhausted through the vent line.through the vent line.– activated carbon canisteractivated carbon canister– vent the fuel tank to the crankcasevent the fuel tank to the crankcase

Carburetor Carburetor LossesLosses

After the engine is shut After the engine is shut off, the gas in the float off, the gas in the float valve evaporates to the valve evaporates to the atmosphere. atmosphere.

This is called h__ s____This is called h__ s____– activated carbon canisteractivated carbon canister– vent to the crankcasevent to the crankcase

Engine Exhaust.Engine Exhaust.

E______ modificationsE______ modifications

F_____ system modificationsF_____ system modifications

E_____ system modifications:E_____ system modifications:– catalytic converter for NOcatalytic converter for NOXX and HC control and HC control

– platinum-rhodium or platinum-palladium platinum-rhodium or platinum-palladium catalyst - requires temp of 350°C (660°F)catalyst - requires temp of 350°C (660°F)

NO + CO + HC ➔ NNO + CO + HC ➔ N22 + CO + CO22 + H + H22OO

Reformulated GasolineReformulated Gasoline

1990 Clean Air Act Amendments had 1990 Clean Air Act Amendments had two performance targets for two performance targets for reformulated gasoline:reformulated gasoline:– 15% r________ in VOCs15% r________ in VOCs– 15% reduction in a___ t______ (e.g., 15% reduction in a___ t______ (e.g.,

benzene)benzene)

Reformulated GasolineReformulated Gasoline

one third of U.S. uses r__________ one third of U.S. uses r__________ gasolinegasoline

Congress mandated that reformulated Congress mandated that reformulated fuel contains 2% o____________fuel contains 2% o____________

CommonCommonOxygenatesOxygenates

M_________M_________

E________E________– fermented from c_____fermented from c_____

MTBE (methyl tertiary butyl MTBE (methyl tertiary butyl ether) derived from natural ether) derived from natural

gas and c_____gas and c_____

ETBE (ethyl tertiary butyl ETBE (ethyl tertiary butyl ether) derived from _____ether) derived from _____