2. بنام خدا عباس بهرامی عضو هیات علمی گروه بهداشت حرفه ای. دانشکده بهداشت دانشگاه علوم پزشکی کاشان Bahrami_a@kaums.ac.ir

5. انتظار میرود در پایان جلسه دانشجو قادر باشد: 1- اجزای ترکیب طبیعی هوا را نام ببرد 2- تعریف آلودگی هوا را بیان کند 3- عوامل موثر بر انتشار آلودگیها را شرح دهد 4- منابع آلودگی هوا را نام ببرد. 5- انواع آلاینده های هوارا توضیح دهد.

6. According to the World Health Organization (WHO), about 2 million premature deaths are caused each year due to air pollution in cities across the world.

8. A recent study has revealed that exposure to fine particle matter in polluted air increases the risk of hospitalization due to respiratory and cardiovascular diseases

10. The Atmosphere 78 percent nitrogen 21 percent oxygen 0.09 percent Argon Carbon Dioxide 0.03 percent Trace elements 0.07 percent –Methane, ozone, hydrogen sulfide, carbon monoxide, etc... Water vapor can range from 0 to 4%

11. Air Pollution Definition: The addition of harmful substances to the atmosphere resulting in damage to the environment, human health, and quality of life. Just one of many forms of pollution, air pollution occurs inside homes, schools, and offices; in cities; across continents; and globally. Ambient (outdoor) air pollution is the focus of this presentation.

12. Stratospheric Ozone 1 atm  101 kPa (From: Introduction to Environmental Engineering G. Masters, 2nd and 3rd eds.)

13. Causes of Air Pollution Car Exhaust The exhaust that comes out of the tail pipe of a car contains carbon monoxide, an odorless, colorless gas, and Nitrogen Oxide. These gases are produced as the car burns gasoline. Coal Plants These plants let off small, airborne particles. These particles are known as soot. Sulfur Dioxides are also gases given off by these plants. Factories Factories emit tons of harmful chemicals into atmosphere on a daily basis. Ammonia gases is just one emitted from these factories. Ozone Chemicals found in paint and hair spray create hazardous pollutants with highly toxic effects. These pollutants form the ground level ozone. Home

16. با تشکر از توجه شما عباس بهرامی

17. Air Pollution I

18. 2- اثرات آلاینده های هوا بر انسان ، حیوان ، گیاه و اموال را توضیح دهد. 3- استاندارد آلودگی هوا را شرح دهد. 4- شاخصهای آلودگی هوا را نام ببرد. انتظار میرود در پایان جلسه دانشجو قادر باشد: 1- حوادث تاریخی ناشی از آلودگی هوا

19. An active adult inhales 10,000 to 20,000 liters of air each day, or 7 to 14 liters every minute.

20. Types of Air Pollution Primary air pollutants:harmful chemicals that enter directly into the atmosphere. Primary air pollutants: harmful chemicals that enter directly into the atmosphere. Secondary air pollutants:harmful chemicals that form from other substances in the atmosphere Secondary air pollutants: harmful chemicals that form from other substances in the atmosphere.

21. Examples of Catastrophic Air Pollution 1911 in London - 1150 died from the effects of coal smoke. Author of the report coined the word smog for the mix of smoke and fog that hung over London. 1952 in London - 4000 died from smog. 1948 in Donora, Penn. Town of 14,000 people - 20 died and 6000 were ill from smog from the community's steel mill, zinc smelter, and sulfuric acid plant. 1963 in New York City - 300 people died from air pollution.

22. London Smog 1952

23. In 13th century London - laws against burning outside because London was already heavily polluted since the middle ages

24. London Smog 1952

25. A Brief History 1930s-60s: severe air pollution episodes: Meuse Valley, Belgium, Donora, Pennsylvania, London, U.K. 1960s-70s: introduction of clean air legislation 1970s-80s: significant reduction in ambient concentrations of many pollutants 1980s, early 1990s: studies demonstrating adverse effects even at lower levels of exposure Mid to late 1990s: large number of studies replicated findings worldwide Late 1990s-present: evaluation of nuances of associations observed in epidemiological studies, effects of specific sources, biological mechanisms, long term effects

26. Local and Regional Pollution Pollution sources tend to be concentrated in cities. In the weather phenomenon known as thermal inversion, a layer of cooler air is trapped near the ground by a layer of warmer air above. Normal air mixing is greatly diminished and pollutants remain trapped in the lower layer. Smog is intense local pollution usually trapped by a thermal inversion.

27. This cloud of smog was typical of the skyline hovering over Los Angeles in the 1940s and 1950s.

28. تاريخچه و حوادث تاريخي آلودگي هوا ) حادثه دره ميوزبلژيك در روز اول دسامبر 1930 به علت وجود وارونگي هوا و تراكم آلاينده‌هاي خروجي از صنايع، اسيد سولفوريك، شيشه سازي و تهيه روي 60 نفرانسان و تعداد زيادي گاو و گوسفند تلف شدند. البته حالت وارونگي حدود 5 روز طول كشيده و بيشتر مرگ و ميرها در روزهاي چهارم و پنجم دسامبر گزارش شده است. غلظت SO2 هوا طي روز‌هاي فوق، تا 38 قسمت در ميليون بوده است.

29. Severe Air Pollution Episodes In 1948 in the steel-mill town of Donora, Pennsylvania, intense local smog killed 19 people. In 1952 in London over 3,000 people died in one of the notorious smog events known as London Fogs; in 1962 another 700 Londoners died in a similar event. Donora, PA at noon on Oct. 29, 1948 Deadly smog envelops the town.

30. دونورا پنسيلوانيا ـ آمريكا از 31 اكتبر 1948 حالت پايدار برفراز شهر دونورا مستقر گرديد وتراكم آلاينده‌ها كه عمدتا از صنايع فولاد ناشي مي‌شوند باعث بيماري 6000 نفر از جمعيت 12 هزار نفري شهر شد كه تعدادي هم بستري شدند. مرگ و مير‌ها در اين حادثه مشخص نشده است.

31. Denora, Pennsylvania 29 Oct 1948

32. لندن مه ـ دود (اسماگ) 5 تا 9 دسامبر 1952 لندن از معروفترين حوادث ناگوار آلودگي هوا است كه طي آن روز‌ها حدود 4000 نفر اضافه مرگ و مير به علت آلودگي هوا گزارش شده است. در اين حادثه نيز كه تراكم ذرات و انيدريد سولفورو به علت پديده وارونگي هوا افزايش يافته بود، مسئول مرگ و ميرها شناخته شده است. در كليه موارد فوق و ساير حوادث مشابه بيشتر قربانيان افراد مسن، بيماران ريوي و اطفال خردسال بوده اند.

33. Summer 2004 ICARTT Campaign (International Consortium for Atmospheric Research on Transport and Transformations) http://www.al.noaa.gov/ICARTT/

35. http://www.epa.gov/airnow//health-prof/EPA_poster-final_lo-res.pdf

36. Health Effects of Air Pollution : Key Findings I Know more about short term effects: More people die and are admitted to hospital for heart and lung problems on days with elevated levels of air pollution These effects are the “tip of the iceberg” relative to other, milder effects A variety of biological mechanisms have been identified for these effects Effects found at levels previously thought to be safe Effects observed using widely varying study designs: large scale population studies to controlled laboratory studies in humans/ animals

37. “Tip of the Iceberg” Adverse health effects that could be avoided every year by meeting the US EPA's daily maximum ozone standard (80 ppb 8-hr) in New York. Figure sections not drawn to scale. From Thurston 1997.

38. Health Effects of Exposure to Ozone and PM 2.5 coughing nose and throat irritation chest pain reduced lung function increased susceptibility to respiratory illness aggravation of asthma children and people with chronic lung disease are particularly at risk increased risk of cardiac arrest and premature death aggravation of asthma respiratory related hospital visits reduced lung function and chronic bronchitis work and school absences children and people with chronic lung disease are particularly at risk Ozone PM 2.5

39. Factors which “cause” asthma (asthma prevalence) Hereditary Exposure to contaminants Cigarette smoke Obeisty Heigene Air Pollution? Factors which provoke asthma (asthma attack) Cigarette Smoke Biological - Pollen, Mold Emotional Stress Indoor Air Quality Weather / Outdoor Air Quality

40. Effects of Air Pollution on Plants Air pollution commonly leads to oxidation damage of both crop plants and wild species.

41. Effects of Air Pollution on Plants Air pollution weakens plants by damaging their leaves, limiting the nutrients available to them, or exposing them to toxic substances slowly released from the soil. Quite often, injury or death of plants is a result of these effects of acid rain in combination with one or more additional threats.

42. Welfare Effects of Air Pollution

43. Effects of Pollution on Buildings For limestone, the acidic water reacts with the calcium to form calcium sulfate: CaCO 3 + H 2 SO 4 CaSO 4 + 2H + + CO 3 2- The calcium sulfate is soluble so it is easily washed away during the next rain storm. Statue carved in 1702 photographed in 1908 (left) and 1969 (right).

44. Criteria Air Pollutants: Ozone Unpleasant appearance in urban cities  photochemical smog Deterioration of synthetic rubber, textiles, paints Gates Corporation http://www.gates.com/brochure.cfm?brochure=2833&location_id=3369 US EPA in How Stuff Works Website, http://science.howstuffworks.com/ozone-pollution.htm

49. Major Pollutants Hydrocarbons and Volatile Organic Compounds: Gasoline, paint, solvents, cleaning solutions. Carbon Monoxide: Carbon Monoxide - highly poisonous gas … attaches to hemoglobin and won’t let go. Nitrogen oxides - contribute to photochemical smog. Catalytic converters are designed to break this down.

50. Major Pollutants Photochemical smog - ozone and hydrocarbons producing peroxyacetylnitrate. Sulfur oxides - Poisonous gas to both plants and animals Lead and other heavy metals Photochemical oxidants - Toxic to plants and animals. Ozone is a “pollutant out of place”.

51. انتظار میرود در پایان جلسه دانشجو قادر باشد : 1- دستگاههاي پاك كننده هوا مربوط به مواد ذره اي در منابع ثابت را نام ببرد. 2- اساس كار دستگاه رسوب دهنده وزني را توضيح دهد. 3- اساس كار دستگاه سيكلون را شرح دهد. 4- نحوه كار فيلتر را بيان كند. 5- سازو كار كاركرد رسوب دهنده الكترو استاتيك را توضيخ دهد.

52. Why Air Pollution Control?

53. Quality of Life This is what you would have lived with in Saint Louis in 1940.

55. Quality of Life This is Saint Louis today, a different kind of air pollution.

56. Yesterday Low Pollution/High Visibility High Pollution/Low Visibility

57. Two Types of Air Pollution Particulate (Visible) Gaseous

58. Three Types Of Control Mechanical Chemical Biological

59. Particulates Regulated Particles 10 microns or less diameter Human hair averages 25 microns 25 microns is 1/1000 inch

60. Example Sources Of Particulate Pollution Wood Processing Rock Quarries Coal Power Plants

61. Particulate Control (Mechanical) Cyclone Fabric Filter (Baghouse) Scrubber Electrostatic Precipitator

62. Cyclone Most Common Cheapest Most Adaptable

64. Cyclone Operating Principle “ Dirty ” Air Enters The Side. The Air Swirls Around The Cylinder And Velocity Is Reduced. Particulate Falls Out Of The Air To The Bottom Cone And Out.

65. Multiple Cyclones (Multi clone) Smaller Particles Need Lower Air Flow Rate To Separate. Multiple Cyclones Allow Lower Air Flow Rate, Capture Particles to 2 microns

67. Fabric Filter (Baghouse) Same Principle As Home Vacuum Cleaner Air Can Be Blown Through Or Pulled Through Bag Material Varies According To Exhaust Character

68. Baghouse

69. About Baghouses Efficiency Up To 97+% (Cyclone Efficiency 70-90%) Can Capture Smaller Particles Than A Cyclone More Complex, Cost More To Maintain Than Cyclones

70. Electrostatic Precipitator (ESP) High Efficiency Able to Handle Large Air Flow Rates Or Can Be Very Small (Smoke Eaters In Bars and Restaurants)

71. How An ESP Operates

72. Electrostatic Precipitator Drawing

73. Principle High-Voltage Charges Wires Gases Are Ionized Particles Become Charged Collection Plates (Opposite Charge) Attract Particles Rapper Knocks Plates So That The Collected Dust Layer Falls Into Hoppers

75. در پایان جلسه انتظار میرود دانشجویان بتوانند: 1- انواع شوینده های تر را نام ببرند. 2- روشهای کنترل گازها و بخارات در منابع ثابت را توضیح دهند. 3- روشهای کنترل بیولوژیکی را شرح دهند.

76. Scrubbers Gas Contacts A Liquid Stream Particles Are Entrained In The Liquid May Also Be A Chemical Reaction Example: Limestone Slurry With Coal Power Plant Flue Gas

77. Tower Scrubber

78. Types Of Scrubber Tray Tower Scrubbers Impingement Tray Sieve Tray Packed Bed Scrubbers Cylinder Filled with Media Which Promotes Gas- Liquid Contact

79. Types Of Scrubber Fiber Bed Scrubber Vertical Mesh Pads Of Interlaced Fibers Promote Gas-Liquid Contact Spray Tower Scrubber Nozzles Spray Liquid Across the Inlet Gas Flow Path

80. Gaseous Pollutant Control

81. Pollutants Of Interest Volatile Organic Compounds (VOC) Nitrogen Oxides (NOx) Sulfur Oxides (SOx)

82. Example Sources Of Gaseous Pollutants Surface Coating Processes Printing Combustion (Boilers) Dry Cleaning Bakeries

83. Mechanical Control For Burners, Air/Fuel Ratio Control, Called Low-NOx Burners. For Dry Cleaners And Similar Processes Using Solvent In Closed Vessels, Refrigerated Condensers.

84. Chemical Control Flue Gas Control Solvent Destruction

85. Flue Gas Control To Reduce Emissions of NOx From Burners: Break NOx Into O2 And N2 With A Catalyst. Same Process As In Autombiles.

86. Flue Gas SOx Control SOx Forms Sulfuric Acid With Moisture In Air Producing Acid Rain. Remove From Flue Gas By Chemical Reaction With Limestone

87. Thermal Oxidizers For VOC Control Also Called Afterburners

88. Two Types Of Oxidizer Catalytic Non-Catalytic

89. Thermal Oxidizer (Non-Catalytic)

90. Catalytic Thermal Oxidizer

91. Biological Method Uses Naturally Occurring Bacteria (Bugs) To Break Down VOC “ Bugs ” Grow On Moist Media And Dirty Gas Is Passed Through. Bugs Digest The VOC. Result Is CO2 And H2O

92. A Bio Filter For VOC Removal

93. ? Questions ?

95. در پایان جلسه انتظار میرود دانشجویان بتوانند: 1- انواع منابع متحرک آلودگی هوا را نام ببرد. 2- روشهای کنترل گازها و بخارات در منابع متحرک را توضیح دهند. 3- روشهای کنترل مواد ذره ای در منابع متحرک را توضیح دهند

97. What are catalysts? Simply put, catalysts are substances which, when added to a reaction, increase the rate of reaction by providing an alternate reaction pathway with a lower activation energy (Ea). They do this by promoting proper orientation between reacting particles. In biochemistry, catalysts are known as enzymes.

98. Catalytic Converters One common application for catalysts is for catalytic converters. Catalytic converters are found in automobiles. Their role is to reduce to emissions of harmful gases (CO, VOC ’ s, NOx) that are the result of the combustion of fuel in vehicle engines.

99. Specifics of Catalytic Converters Most modern cars are equipped with three-way catalytic converters. "Three-way" refers to the three regulated emissions it helps to reduce -- carbon monoxide, VOCs and NOx molecules. The converter uses two different types of catalysts, a reduction catalyst and an oxidization catalyst. Both types consist of a honeycomb-shaped ceramic structure coated with a metal catalyst, usually platinum, rhodium and/or palladium. A: Reduction Catalyst B: Oxidation Catalyst C: Honeycomb Ceramic Structure

100. Step 1: The Reduction Catalyst The reduction catalyst is the first stage of the catalytic converter. It uses platinum and rhodium to help reduce the NOx emissions. When an NO or NO 2 molecule contacts the catalyst, the catalyst rips the nitrogen atom out of the molecule and holds on to it, freeing the oxygen in the form of O 2. The nitrogen atoms bond with other nitrogen atoms that are also stuck to the catalyst, forming N 2. The equation for this is as follows: 2 NO => N 2 + O 2 or 2 NO 2 => N 2 + 2 O 2

101. Step 2: The Oxidization Catalyst The oxidation catalyst is the second stage of the catalytic converter. It reduces the unburned hydrocarbons and carbon monoxide by burning (oxidizing) them over a platinum and palladium catalyst. This catalyst aids the reaction of the CO and hydrocarbons with the remaining oxygen in the exhaust gas. The equation for this process is as follows: 2 CO + O 2 => 2 CO 2 Once this process is complete, most of the harmful substances have been broken down into harmless ones such as N 2, O 2, and CO 2.

102. Catalysts in Industry Of course, reducing vehicle emissions is not the only area in which catalysts can prove useful. The petrochemical industry also makes great use of them in various processes. One of these processes, called catalytic cracking, is detailed below. Catalytic cracking is the name given to the breaking up of large hydrocarbon molecules into smaller, more useful pieces.

103. Catalytic Cracking: Part 1: Hydrocarbons are the result of the fractional distillation of gas oil from crude oil (petroleum). These fractions are obtained from the distillation process as liquids, but are re-vaporised before cracking. The hydrocarbons are mixed with a very fine catalyst powder. These days, the catalysts are zeolites (complex alumniosilicates). In the past, the catalyst used was aluminum oxide and silicon dioxide, however, these are much less efficient than the modern zeolite. The whole mixture (hydrocarbons and zeolites) is blown through a reaction chamber at a temperature of about 500 C. The catalyst is recovered afterwards, and the cracked mixture is further separated by cooling and fractional distillation.

104. CATALYTIC CONVERTERS Catalytic converters remove harmful gases from car exhausts. It consists of a honeycomb of ceramic with metals such as platinum,palladium and rhodium coated on the honeycomb It removes up to 90% of the harmful gases CO No x C 8 H 18 CO 2 N 2 H 2 O Catalytic converter

105. EQUATIONS FOR REACTIONS IN THE CATALYTIC CONVERTER CO + NO CO 2 + N 2 222 C 8 H 18 + NO CO 2 + N 2 + H 2 O25812 1/2 9

106. EXAMPLES OF POISONING OF CATALYSTS Leaded petrol cannot be used in cars fitted with a catalytic converter since lead strongly absorbs onto the surface of the catalyst Cannot use copper or nickel in a catalytic converter on a car instead of the expensive platinum or Rhodium. REASON :- Any SO 2 present in the exhaust fumes (trace amounts ) would poison the catalyst Once the catalytic converter has become inactive it cannot be regenerated

107. Control of exhaust for unburned HC and CO involves: fuel modifications minimizing pollutants from the combustion chamber - better engineering of motors oxidation of pollutants outside the combustion chamber - either by normal combustion, or by catalytic oxidation. Requires pumping of air to the exhaust stream.

108. To lower NOx, two systems are used: exhaust gas recirculation sends part of the exhaust stream back into the intake manifold which reduces the combustion temperature and decreases NOx production (tolerated when ``power'' is not required); a second catalytic converter can be used in series with the HC/CO converter to decompose NOx to O and N.

109. ENVE 4003 MOBILE SOURCES Types of emissions, control technologies and trends, inspection and maintenance programs.

110. Motor Vehicles Internal combustion (IC) engines Spark ignition (SI) - gasoline, propane, natural gas, ethanol 4-stroke vs 2-stroke Compression ignition (CI) - diesel, biodiesel

111. Figure 13.1 de Nevers Schematic of piston and cylinder in IC engine

112. Figure 18.2 Cooper & Alley Schematic of four stroke IC engine

113. Figure A3.1.5 Faiz, Weaver & Walsh Two stroke motorcycle engine

114. Figure A3.2.1 Faiz, Weaver & Walsh Diesel combustion stages

115. MOTOR VEHICLE EMISSIONS Regulated (criteria pollutants) : CO, NOx, NMHC, PM Non-regulated: Individual (speciated) HCs carbonyl compounds (alcohols, aldehydes, ketones) Air toxics, e.g. benzene, toluene, ethylbenzene, 1,3,butadiene, formaldehyde, acetaldehyde CO2 (i.e. fuel economy)

116. Table 13.1 de Nevers Contribution of motor vehicles to U.S. national emissions

117. MOTOR VEHICLE EMISSIONS Exhaust (tailpipe) (CO, NOx, VOC, PM) Evaporative (VOC) Resting Diurnal heat build Hot soak Running Refuelling

118. COMBUSTION IN IC ENGINES Air/Fuel ratio, mass of air per mass of fuel, ~15 Normalized A/F ratio, = (A/F) actual / (A/F) stoichiometric Equivalence ratio:  = (A/F) stoichiometric / (A/F) actual   1 for gasoline engines most of the time,  > 1 (fuel rich) during high power demand and start  < 1 (fuel lean) for diesel most of the time, ignition - combustion - extinction sequence repeated 10 2 ~ 10 3 times a minute; unsteady combustion

119. Figure (13.2) de Nevers Emissions and fuel consumption vs lambda

120. Figure 10.16 (7.5) de Nevers Effect of air-fuel ratio and quality of mixing on composition of combustion gases

121. Table 13.3 de Nevers Equivalence or A/F ratios

122. POLLUTANT FORMATION MECHANISMS - SI ENGINES HC Rich Fuel/Air mixture, “ oxygen deficit ” Flame quenching at walls, crevices, “ quench zone ” CO Rich Fuel/Air mixture, “ oxygen deficit ” “ incomplete reaction ”, even with sufficient oxygen NO, Thermal;  T compression ~ 600 F  T combustion ~ 3600 F Short times but high peak temperatures

123. DIESEL COMBUSTION CHARACTERISTICS Only air is compressed during compression stroke, reaching 700-900 C Fuel is injected into hot air just before top of compression stroke A fuel-air mixture forms around the periphery of the fuel jet and ignites after an ignition delay. This premixed combustion phase accounts for only a fraction of the fuel and causes a pressure peak The remainder of the fuel burns under mixing controlled combustion causing a more gradual pressure increase, and then decline with expansion

124. DIESEL NOx FORMATION CHARACTERISTICS Most NOx formed during the high T and P premixed combustion phase NOx formation can be reduced effectively by reducing flame temperature: delay combustion into the expansion phase cool the air charge going into the cylinder exhaust gas recirculation (EGR)

125. PARAMETERS AFFECTING DIESEL PM AND HC EMISSIONS Air/Fuel ratio, generally lean overall, to allow for complete combustion within limited time available for mixing Minimum  = 1.5 for smoke point, smoke increases dramatically below this limit Rate of air-fuel mixing, can be enhanced by imparting a swirl to the injected fuel fuel injection timing compression ratio temperature and composition of charge in the cylinder

126. DIESEL VISIBLE SMOKE Black smoke : from soot White, blue or gray smoke: condensed hydrocarbon droplets in the exhaust Blue or gray generally due to vaporized lubricant White due to cold start Sulfur in the fuel forms sulfuric acid which is later sampled as PM

127. Table 13.5 de Nevers Comparison of gasoline and diesel engines

129. VEHICLE EMISSION CONTROL Control technology is aimed at reducing the second term: fuels, engines, vehicles etc. Urban and transportation planning addresses the first term: housing density, location, transportation infrastructure the second term is relatively insensitive to the number of passengers in the vehicle Increasing vehicle occupancy helps reduce emissions: mass transit, car pooling etc.

130. CONTROL TECHNOLOGY - SI Air/Fuel ratio. CO and HC emissions increase as mixture gets richer in fuel (start and high power conditions), NOx emissions peak near stoichiometric ratio Fuel metering systems: carburetors and fuel injectors (throttle body TBI, multi-port PFI, simultaneous or sequential) Electronic Control Systems adjust the air/fuel ratio based on the signal from an oxygen sensor in the exhaust

131. EXHAUST GAS RECIRCULATION (EGR) - SI AND CI ENGINES Dilutes Air/Fuel mixture with exhaust gases thereby reducing peak combustion temperatures and NOx formation There are limits to how lean an air-fuel-exhaust gas mixture can be for ignition Ignition systems (spark plugs etc.) and combustion chambers can be designed to improve performance with these lean mixtures

132. EXHAUST AFTERTREATMENT SI ENGINES Air injection - thermal oxidation of residual CO and HC with excess air introduced after the engine into the exhaust system, very temperature sensitive: Minumum 600 C for HC, 700 C for CO Catalytic convertors can achieve conversion at lower temperatures ~ 350 C Oxidation (two-way) catalyst - for HC and CO Oxidation-reduction (three-way) catalyst (TWC) for HC, CO, and NOx according to:

133. CATALYTIC CONVERTORS SI ENGINES Pellet and monolith types Require near stoichiometric combustion for effective conversion of all three pollutants, CO and HC conversion efficieny drop for rich mixtures, NOx conversion efficiency drops for lean mixtures Exhaust gas oxygen sensor (Zirconia, ZrO 2 based) essential to keeping the Air/fuel ratio in window of optimum conversion efficiency for all three

135. TWC picture from ICT- Umicore CD

137. EVAPORATIVE EMISSION CONTROL SI ENGINES Blowby and Crankcase emissions - fuel and partial combustion product molecules pass by the piston into the crankcase - recycled back to air intake manifold by Positive Crankcase Ventilation (PCV) Charcoal canister for capturing fuel tank, carburetor and miscellanous evaporative emissions. Adsorption during hot-soak, diurnal heat build (breathing), refuelling periods, desorption into the air intake during engine operation (regeneration)

139. CONTROL TECHNOLOGY - CI PM and NOx more important in diesel exhaust than CO and HC, relative to gasoline exhaust A general trade-off between PM and NOx exists although reductions in absolute levels of both emissions have been achieved Emissions more strongly dependent on engine design - most emission reductions so far have been achieved through combustion modifications rather than exhaust aftertreatment in contrast to gasoline engine emissions

140. DIESEL PM FORMATION CHARACTERISTICS Particulate Matter forms in fuel rich zones primarily during the mixing controlled combustion phase mostly an aggregate chain carbon core (soot) adsorbed hydrocarbons (aliphatic and polyaromatic): soluble organic fraction (SOF) significant fraction of SOF may come from lubricating oil Most of the PM formed during combustion is subsequently burned during the expansion stroke, the unburned part forms the emissions Sulfur in the fuel forms sulfuric acid which is later sampled as PM

141. DIESEL EXHAUST AFTERTREATMENT Flow through oxidation catalyst (two-way catalytic convertor) for reduction of CO and VOC (80%), and PM SOF (20-30%), does not retain PM Trap oxidizer (Diesel particulate filter), reduce PM by 95%, filter + oxidation (regeneration) functions active and passive regeneration types Passive regeneration: catalyst coated onto trap or added to fuel bring regeneration temperature down to 400-450 C which can be achieved in diesel exhaust Active regeneration monitors PM build-up on the trap and triggers regeneration by diesel fuel burning, electric heating, catalyst injection

142. DPF from ICT-Umicore CD

143. DPF detail from M.Walsh

148. EXHAUST EMISSION MEASUREMENT Simulated driving conditions Mass Emission rates in g/km for light duty vehicles (LDV) on a chassis dynamometer Mass Emission rates in g/kWh for heavy duty (HD, diesel) engines on an engine dynamometer Actual driving conditions “ On-board ” measurement systems Tunnel studies Remote sensing, g/L of fuel burned

149. EVAPORATIVE EMISSION MEASUREMENT SHED Test, Sealed Housing Evaporative Determination Carbon canisters attached to various points on vehicle to adsorb HC vapors

150. DRIVING OR OPERATING CYCLES Actual vs Synthesized Transient, steady state, multi-mode Modal analysis: Acceleration Cruise Deceleration Idle

151. EMISSION FACTORS Amount of pollutant emitted per unit activity: g/km, (distance travelled) g/kWh, (mechanical energy delivered) g/L, (quantity of fuel burned) For a single vehicle with given engine and emission control technology, the factors that influence the emission factor are: speed, acceleration/deceleration, trip length, ambient temperature Vehicles with similar size, engine, and emission technology may be expected to show similar emission behaviour

152. EMISSION FACTORS AND EMISSION MODELLING Regulated emissions from new vehicles vs emissions from in- use vehicles Emissions surveillance program to test emissions from thousands of in-use vehicles at different ages in the U.S. Emission modelling from motor vehicles involves the consideration of different types of vehicles and their driving conditions to arrive at a grand total

153. INSPECTION AND MAINTENANCE PROGRAMS Field studies suggest that more than 50% of motor vehicle pollution may come from less than 10% of vehicles which have poorly maintained or malfunctioning emission control devices Inspection and maintenance (I/M) programs aimed at identifying such gross-emitter vehicles and ensuring the repair of their emission control systems are becoming more important in the face of reduced emission regulations for new vehicles Remote sensing of CO, HC, and NOx, along with CO 2 offers both I/M and fuel-based emission inventory advantages

154. I/M PROGRAMS Emission control technology for LDGV very effective; 90--95% reduction compared with no controls Emission control system performance deteriorates with vehicle age but only gradually Emissions from a small fraction of vehicles with malfunctioning control systems erode the benefits of emission reductions from a large number of vehicles I/M programs aim to maintain control system efficiency for the entire fleet, over the useful life of vehicles

155. I/M PROGRAMS Objectives: Identify and repair vehicles with maladjustments or control system malfunctions Discourage willful tampering with control systems Modes: Periodic checks of all vehicles Identification and repair of high emitting vehicles, Identification and exemption of low emitting vehicles, “ clean screening ”

156. I/M PROCEDURES SI Engines Exhaust concentrations measurement; CO, HC, NOx No load, idle/2500 rpm Loaded dynamometer tests ASM, Acceleration simulation mode (AMS2525, 25 mph, 25% maximum FTP acceleration) IM240, first 240 seconds of FTP (Federal Test Procedure) Visual inspection of control system components Pressure/purge tests for evaporative emission control systems CI Engines Bosch method for smoke: pull measured amount of exhaust through filter paper, check light transmission of filter Opacity meter: check light attenuation directly across exhaust path under “ snap acceleration ” conditions

157. I/M PROGRAMS Institutional setting: Centralized - inspection Decentralized - test and repair Frequency Vehicle age at first test, 1-4 years Subsequent tests every 1-2 years Costs Program operating costs Repair costs Cost/benefit ratio Improvement in ambient air quality vs I/M costs

158. I/M PROGRAMS - COMPLEMENTS Remote sensing Clean screening, high emitter profiling On-board diagnostics (OBD) Sensing and monitoring devices to detect malfunctions Light indicator Stored computer codes for malfunctioning components: catalyst oxygen sensor engine misfire evaporative system integrity

159. Pb, S, and Transportation fuels Pb used to be added to gasoline (tetra-ethyl lead TEL) as an octane enhancer. Phased out in most countries and being phased out in others: permanent poisoning of TWC – using leaded gasoline in a vehicle with TWC once is sufficient to make the TWC useless Neuro-toxic health effects on children

160. Pb, S, and Transportation fuels S is a natural component of crude oil. Can be removed effectively by hydrodesulfurization. Adverse (though reversible) effect on efficiency of TWC and DPF. Low sulfur fuel increases efficiency of modern TWC and makes it possible to use advanced diesel exhaust after- treatment like DPF contribution to PM emissions as sulfate contribution to gaseous Sox emissions Current trends: coming down to 15 ppm (ULSD ultra low sulfur diesel), from 300-500 ppm.

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