Traffic Emission Controls

1. Traffic Emission Controls Dr.Wesam Al Madhoun

2. Before beginning to understand emission controls you should know the reason why emission controls were installed into the automobile. 1. To reduce the amount of pollutants entering the atmosphere . Emission Controls

3. Smog is a term developed from smoke. Smog is form when airborne pollutants is formed with oxygen and other atmospheric gasses to produce a grayish yellow smoke. The resulting smoke is called photochemical smog.

4. Smog • Smog is can be a major problem in larger cities (New York and LA) • Smog can be harmful to • A. Humans • B. Plants • C. Animals and even effect paint rubber and other materials.

5. Smog • One of largest producer of photochemical smog is the automotive internal combustion engine. • The EPA (environmental protection agency) begin putting restriction on automotive manufactories in the mid 60.

6. Motor Vehicle Emissions • Motor vehicle emission are emission produce by motor vehicles. They include • A. Hydrocarbons (HC) • Carbon monoxide (CO) • Oxides of nitrogen (NOx)

7. Hydrocarbons (HC) are emission of unburned petroleum products being released into the atmosphere. All petroleum products and made of hydrocarbons (hydrogen and carbon compounds) this includes: Gasoline LP-gas. Diesel motor oil. Exhaust Gasses

8. Hydrocarbons are produced because of incomplete fuel combustion or fuel evaporation. Hydrocarbons emission is considered a hazardous form of air pollution because of. Eye. Throat. Lung irritation. And possibility cancer. Exhaust Gasses

9. Exhaust Gasses • In the US a vehicle must not exceed 220 ppm of hydrocarbons emissions. • High hydrocarbon emission are the results of a: • cylinder misfire. • Improper ignition timing • Pumping oil into the combustion chamber

10. Exhaust Gasses • Carbon monoxide emission are exhaust emission that is the result of partially burned fuel. • A high carbon monoxide emission can be caused by a: • Restricted or dirty air cleaner. • Advance ignition timing. • Clogged fuel injectors.

11. Exhaust Gasses • Oxides of nitrogen, (NOx) are emission produced by extreme heat. • Air consist of approximately 79% nitrogen and 21% oxygen • When combustion chamber temperature reaches 2500 degrees F or 1370 degrees C nitrogen and oxygen combine to produce oxide of nitrogen (NOx)

12. In the US the standard for Carbon Monoxide is 1.2 % of the total exhaust output. Muffler HC 220 ppm CO 1.2% Exhaust output

13. Exhaust Gasses • Oxides of nitrogen is responsible for the dirty brown color is SMOG. • NOx is a eye and respiratory irritant. • Newer high compression, leaner air fuel mixture and hotter running engine produces more NOx than earlier engine.

14. Exhaust Gasses • The same factors that increases NOx will tend to improve fuel mileage and lower HC and CO2 production. • This means that to increase fuel economy and lower HC and CO2 production NOx will increase. • For this reason emission controls have been added to lower all form of emissions

15. Exhaust Gasses NOx increases HC increases Richer Leaner 14.7 – 1 AFR Hc and Co decreases NOx decreases

16. Exhaust Gasses • Before understanding emission controls we need to first understand where they come from. • Particulates: are solid particle of carbon soot and fuel additives that blow out the tail pipe. • Engine crank case blow by. Caused by heating of oil and unburned fuel vapors that blow past the engine rings.

18. Exhaust Gasses • Fuel vapors: different chemicals that enter the atmosphere as fuel evaporates. • Engine exhaust gasses: are harmful chemical that are produced inside the combustion chamber and are blow outer the tail pipe.

19. HC CO Solid particulate Catalytic Converter Exhaust manifold Fuel Tank Air Fuel Pump Fuel Fuel Vapors Fuel

20. Exhaust Gasses • Automotive manufactures agree the best way to lower exhaust emission is to burn all the fuel entering the combustion chamber. • Modern engine have introduced several modification to ensure all fuel entering the combustion chamber is burned.

21. Some engine modification are: • Lower compression ratio, by lowering compression ratio vehicle can burn unleaded fuel. • It is the ratio between the volume of the cylinder and combustion chamber when the piston is at the bottom of its stroke, and the volume of the combustion chamber when the piston is at the top of its stroke. • The use of unleaded fuel allows for catalytic converters that help reduce HC and CO emissions. • Lower compression ratio also lower combustion temperature reducing NOx emission.

22. Smaller combustion chambers, allows for more heat to remain inside the combustion chamber that can aid in the burning of fuel. • Reduce quench areas, the areas between the piston and the cylinder head is the quench area. • If this areas is too close, fuel will not burn completely increasing HC and CO emissions. • Modern engine are design to reduce high quench areas.

23. Exhaust Gasses Quench area

24. Exhaust Gasses • Decrease valve overlap, is used to decrease exhaust emission. • A larger valve overlap increases power but dilutes incoming fuel mixture and requires a richer air fuel mixture at lower engine speed therefore increasing HC and CO emissions.

25. Overlap Intake Exhaust

26. Exhaust Gasses • Higher combustion chamber temperature, are used to reduce HC and CO emissions. • Today vehicles used hot thermostats than earlier model helping to increase combustion chamber temperature. • Leaner air-fuel mixtures help fuel burn better, lower HC and CO emissions. • Wider spark plug gaps, are used to burn the leaner fuel mixture and helps prevent spark plug fouling.

27. Thermostats are now 190 degrees Wider spark plug gap

28. Vehicle Emission Control • There are several different types of emission control system used on modern vehicles. • Positive crankcase ventilation system (PCV) is used to re-circulate engine crankcase fumes back into the combustion chamber.

29. A PCV valve uses manifold vacuum to draw blow-by gasses from the engine into the intake manifold for re-burning by the engine. • In earlier years automotive manufactories uses road draft tubes to remove crankcase blow by gasses.

30. Vehicle Emission Control • The uses of road drift tube allowed for blow by gasses containing HC, CO, particulates, sulfur and small amounts of water to be vented in the atmosphere. • At idle when there is high engine vacuum the PCV valve is opened to remove blow-by gasses from inside the engine.

31. Vehicle Emission Control • When engine Vacuum is High PCV valve plunger is nearly closed • When engine vacuum is low plunger Opens. Allowing exhaust gasses into Engine. PCV Plunger Typical PCV valve

32. Evaporative Emissions Control SystemsEVAP • The EVAP system prevents Hydrocarbons in the form of fuel vapors from entering the atmosphere even when the vehicle is not running. • An EVAP system is considered a closed system. • Fuel vapor are stored in a charcoal canister when the engine is off.

33. When the engine is started vacuum pulls fuel vapors into the engine for burning. • EVAP system different from per emission vehicle because no fuel or vapor is vented into the atmosphere.

34. Unvented Fuel Cap Rollover Valve Intake Manifold Vacuum Charcoal Canister Fuel Tank

35. A rollover valve is uses to prevent fuel spillage in case of a rollover. • A liquid-vapor separator is sometime used to prevent liquid fuel from entering the charcoal canister. • A charcoal canister is used to store fuel vapor when the engine is not operating.

36. Exhaust Gas Recirculation System (EGR) • An EGR system has two important jobs 1. The recirculation system is used to burn un-burns gasses (HC and CO) By recirculation of un-burn gasses lower emissions can be achieved. 2.Lowering combustion chamber temperature. By lowering combustion chamber temperature NOx emission can be lowered.

37. 0 Vacuum Gauge Vacuum off throttle Exhaust Gasses Exhaust Gasses to Engine

38. Charcoal Canister EGR Valve

39. Catalytic Converters • In the mid 70s automotive manufacture begin installing catalytic converters to assist in meeting tougher emission standards. • A Catalytic is a material that can speed-up chemical action without changing itself.

40. Catalytic Converters • Automotive catalytic converter are made of platinum, palladium and rhodium or a combination of these materials. • Platinum and palladium are used to change HC and CO into CO2 and Water. • Rhodium acts to reduce NOx emissions

41. Catalytic Converters • Due to enhance emissions standard, later model catalytic converters now use cerium to attract and release oxygen inside the converter to aid in the process of changing HC and CO to CO2and H2o

42. The catalyst agent inside a catalytic converter is either ceramic beds or a honeycomb-shaped blocks. • All catalytic converters are encased in a stainless steel housing. • NOTE: stainless steel is used on newer vehicle with catalytic converters because the production of water will rust traditional exhaust system in only a few years

43. Catalytic Converter CO2 H2o HC and CO Engine Exhaust Flow from engine through converter

44. Catalytic Converters • Stainless steel catalytic converter housing are design to resist heat. • Before the catalytic converter can operate, an operating temperature of around 300 degrees F must be reached.

45. This is a honey-comb block type catalytic converter. • Exhaust gasses flow through the honey-comb block

46. There are a few different types catalytic converters. • Monolithic Converter • Two way converter • Three way converter • Dual bed converter • Monolithic converter uses a ceramic honey-comb catalytic

47. Two way catalytic converters only convert HC and CO • With a two way converter NOx is not converted • Two way converter are coated with platinum only • Two way converter are sometime referred to as oxidation converters

48. Catalytic Converters • Three way catalytic converters can convert all three exhaust gasses • HC • CO • NOx

49. Catalytic Converters • A three way catalytic converter is usually plated with rhodium and platinum • Three way converter are also called reduction converters.

50. Catalytic Converters • Dual bed catalytic converter is an oxidation and reduction converter built into one unit. CO, HC and NOx CO2 and H20 Mixing Chamber