Mobile Sources Chp 17 Mobile Source Definition Vehicle

Mobile Sources (Chp 17) • Mobile Source Definition • Vehicle Emissions • Characteristics of Engines – Types of engines: ( gasoline vs diesel, 4 -strokes vs 2 -strokes) • Emission standards and Emission Control: • Add-on Control Device – catalytic converter • Green Cars: Hybrid Vehicles and Fuel Cells 2020/9/15 1

Mobile Sources § All things that move and emit air pollutants are mobile sources – – – 2020/9/15 Cars Diesel Trucks/Buses Aircraft Ships Motorcycles Others ENVE 542 2

Example 17. 1 § Between 1980 and 1990, the average CO emission factor (EF) of the vehicle fleet in Orange County, Florida, dropped by almost half, from about 65 to 34 grams/veh-mile. However, the total miles driven in the county increased by 60% during this same time period. Did county-wide emissions of CO go up or down, and by how much? 2020/9/15 ENVE 542 3

SOLUTION to Example 17. 1 Emissions 90=Emission 80 x(EF 90/EF 80)x. Vehicle Growth = Emission 80 x (34/65)x 1. 60 = Emission 80 x 0. 837 So emissions decreased from 1980, but only by about 16%. 2020/9/15 ENVE 542 4

Vehicle Emissions Motor vehicles emit all of the primary pollutants and contribute to the formation of ozone in urban areas Vehicular Pollutants depend on the fuel used: In the US, CO, NOx and VOC are the pollutants of more concern while SO 2 and PM from vehicles are of less concern due to relatively low percentage of diesel vehicles Total world production of motor vehicles (cars, trucks, and buses) grew from about 10 million/year in 1950 to 50 million/year in 1990. 2020/9/15 ENVE 542 5

Emmisions of Air Pollutants from Mobile Sources From Cofala, et al. Atmospheric Environment, 2007, 41: 38. 2020/9/15 ENVE 542 6

Types and Numbers of Vehicles in Use 2020/9/15 ENVE 542 7

Vehicles Fleets in the World 2020/9/15 ENVE 542 8

Charachteristics of Engines in Mobile Sources Most cars are powered by a conventional four stroke gasoline burning Internal Combustion Engine ENVE 542

Charachteristics of Engines in Mobile Sources http: //www. animatedengines. com/otto. html Intake compression power This process is repeated several hundred times per minute for each cylinder during driving

Combustion Reaction- Air/Fuel Ratio C 8 H 18 (octene) +12 O 2+45, 1 N 2 8 CO 2+8 H 2 O+45, 1 N 2 Instead of molar ratio, it is common to use the mass air to-fuel ratio (AFR). Stoichiometric AFR = 14. 7 which is typical value for many distillate hydrocarbon fuels. Equivalence ratio (ER) =lambda =(A/F)actual/(A/F)stoich A=air intake rate, g/s F=fuel usage rate, g/s If ER>1 fuel lean or lean If ER<1 fuel rich or rich 2020/9/15 ENVE 542 11

Air/Fuel Ratio 2020/9/15 ENVE 542 12

Example 17. 3 a)Calculate the stoichiometric air-to-fuel ratio for the combustion of benzene, one of the aromatic compounds found in gasoline b) For an equivalence ratio of 1. 10, calculate the volume of exhaust gases produced at STP per kg of benzene burned SOLUTION: a) C 6 H 6+O 2+N 2 CO 2+H 2 O+N 2 Let’s balance it stoichiometrically starting with C atoms then H, O 2 and N 2. Note that for every mole of O 2, 3. 76 moles of N 2 are present in air. C 6 H 6+7. 5 O 2+28. 2 N 2 6 CO 2+3 H 2 O+28. 2 N 2 2020/9/15 ENVE 542 13

Example 17. 3 C 6 H 6+7. 5 O 2+28. 2 N 2 6 CO 2+3 H 2 O+28. 2 N 2 AFRstoich = 13. 2 g air/g benzene 2020/9/15 ENVE 542 14

Example 17. 3 b) For an equivalence ratio of 1. 10, calculate the volume of exhaust gases produced at STP per kg of benzene burned SOLUTION: b) For an ER of 1. 10 , the rebalance equation is C 6 H 6+8. 25 O 2+31. 0 N 2 6 CO 2+3 H 2 O+31. 0 N 2+0. 75 O 2 78 g 264 g 868 g 264 g 54 g 868 g 24 g In this case for every 78 g of benzene, there are 1132 g of air and 1210 g of exhaust gas. Exhaust gas volume at STP per 1 kg benzene (V)= 1 mole gas at STP (25 C, 1 atm)=24. 45 l 2020/9/15 ENVE 542 15

2 -stroke Engines -have no separate strokes for intake and exhaust -the spark plug fires every time the piston approaches the top of the cylinder -due to lubrication of the internal working parts, the motor oil mixes with the fuel in the gas tank. The oil is more difficult to burne completely than the gasoline 2020/9/15 ENVE 542 16

2 -Stroke Engine Compression stroke Power stroke http: //media-2. web. britannica. com/ebmedia/10/310 -004 -58 E 43 DBF. gif 2020/9/15 Aerosol & Particulate Research Lab 17

2 -Stroke Engine Advantages and Disadvantages over 4 -Stroke Engine Smaller, lighter, less expensive, simpler to operate, easier to maintain external cost associated with air pollution they cause For CO and VOC : 75 to 750% greater than emissions from comparable four stroke engines NOx: slightly lower PM: up to 1000% greater 2020/9/15 ENVE 542 18

Motorcycles • Small number in US (0. 6% of HC, 0. 1% NOx and <0. 1% of PM of all mobile sources); large in developing countries • Higher emissions per mile than a car or even a SUV Thailand Tutu Highway Motorcycle Exhaust Emission Standards Class Engine Size (cc) Implementation Date HC (g/km) HC+NOx (g/km) CO (g/km) I < 170 2006 1. 0 - 12. 0 II 170 -279 2006 1. 0 - 12. 0 III > 280 2006 - 1. 4 12. 0 2010 - 0. 8 12. 0 http: //www. epa. gov/otaq/roadbike. htm 2020/9/15 Aerosol & Particulate Research Lab 19

Diesel Engine Liquid diesel injection 700 – 900 o. C from compression Ignition delay Diffusion flame 2020/9/15 Aerosol & Particulate Research Lab 20

Advantages and Disadvantages over 4 -Stroke Engine • • • Diesels get great mileage. They typically deliver 25 to 30 percent better fuel economy than similarly performing gasoline engines. Diesel fuel is one of the most efficient and energy dense fuels available today. Diesels have no spark plugs or distributors. Therefore, they never need ignition tune-ups. Diesel engines are built more ruggedly to withstand the rigors of higher compression. Consequently, they usually go much longer than gas-powered vehicles before they require major repairs. Mercedes-Benz holds the longevity record with several vehicles clocking more than 900, 000 miles on their original engines! 2020/9/15 ENVE 542 21

Advantages and Disadvantages over 4 -Stroke Engine Environmental concerns: has been shown to produce carcinogens, soot and NOx, which can be just as harmful to the environment. Financial considerations: Gasoline cars are cheaper as new purchases, as diesel cars can be around $700 more expensive. Noise and smoothness of ride. it is still louder than the gas car and provides less of a smooth ride which can make the drive a less pleasurable experience 2020/9/15 ENVE 542 22

Vehicle Emissions for Road Vehicles (per vehicle kilometre) * Petrol cars without catalysts have been given a relative value of 100 for Vehicles Carbon monoxide Hydro - carbons Oxides of nitrogen Particulate matter Carbon dioxide * Petrol car without a catalyst 100 100 --- 100 Petrol cars with a catalyst 42 19 23 --- 100 Diesel cars without a catalyst 2 3 31 100 85 2020/9/15 ENVE 542 23

Emission Standards in Turkey 8 Temmuz 2005 tarih ve 25869 sayılı Resmi Gazetede yayımlanan “Trafikte Seyreden Motorlu Kara Taşıtlarından Kaynaklanan Egzoz Gazı Emisyonlarının Kontrolüne Dair Yönetmelik” yürürlükten kaldırılarak yerine 4 Nisan 2009 tarih ve 27190 sayılı “Egzoz Gazı Emisyonu Kontrolü Yönetmeliği” Resmi Gazetede yayımlanarak yürürlüğe girmiştir. 2020/9/15 ENVE 542 24

Emission Standards in Turkey (Tablo-1): Trafikte kullanılmakta olan benzin motorlu taşıtlarda karbon monoksit sınır değerleri: • . TAŞITA AİT BİLGİ Egzoz sisteminde katalitik dönüştürücü ve benzeri emisyon kontrol donanımı olmayan taşıtlar Rölantide 1/10/1975 den öncekiler 1/10/1975 -1/10/1986 arasındakiler 1/10/1986 sonrakiler Egzoz sisteminde katalitik dönüştürücü ve benzeri emisyon kontrol donanımı olan taşıtlar Rölantide (<2000 min– 1) * Taşıt üreticisinin belirlediği bir CO miktarı yok ise 70/220/AT Yönetmeliğinin 98/69/AT değişikliğine göre tip onayı alan taşıtlar veya 2003 model yılından itibaren Yüksek Rölantide (≥ 2000 min– 1) Taşıt üreticisinin belirlediği bir CO miktarı yok ise 70/220/AT Yönetmeliğinin 98/69/AT değişikliğine göre tip onayı alan taşıtlar veya 2003 model yılından itibaren Karbon Monoksit ( hacimce % ) 6 4, 5 3, 5 En fazla 0, 3 En fazla 0, 2 Lambda değeri: Gerçek hava/yakıt oranının teorik hava/yakıt oranına bölünmesi ile bulunan değeri, üreticisinin belirlediği şartlara göre 1+/- 0, 03. 2020/9/15 ENVE 542 25

Emission Standards (Tablo- 2): Trafikte kullanılmakta olan dizel motorlu taşıtlarda absorpsiyon katsayısı sınır değerleri TAŞITA AİT BİLGİ ABSORPSİYON KATSAYISI m-1 -Normal emişli dizel motorlarda -Aşırı doldurmalı dizel motorlarda ( Türbo Şarjlı ) 2, 5 3, 0 • Absorbsiyon katsayısı: Duman koyuluğunu gösteren ve egzoz gazı içinden geçen ışığın soğurması ile ölçülen katsayı § Duman koyuluğu: Tam şeffaf gaz için duman koyuluğu % 0, ışığı tamamen absorbe eden, geçirgen olmayan gaz için ise % 100 olmak üzere egzoz gazı içerisinde bulunan, şeffaf olmayan parçacıkların, gazdan geçen ışığın aydınlatma şiddetini, yani aydınlanan birim yüzey için ışık akısını, azaltma yüzdesi. 2020/9/15 ENVE 542 26

Emission Standards in the US CAA 1977 CAAA 1990 CAAA 2020/9/15 Aerosol & Particulate Research Lab Asif Faiz et al. , 1996, Air Pollution from Motor Vehicles 27

2020/9/15 Aerosol & Particulate Research Lab 28

• Heavy Duty Vehicles – For the same power output, only 70% mass compared to gasoline engines – Less volatile, Lower CO 2 emission – Lower operating cost, 2/3 of an equivalent gasoline truck VMT: Vehicle Miles Traveled Lloyd and Cackette, JAWMA, 51, 2001, p 809 -847. 2020/9/15 Aerosol & Particulate Research Lab 29

• Heavy Duty Vehicles (cont. ) – – – Contains S (500 ppmw): new regulation just kicked in 2006 Lower operating speed, slower thrust/acceleration Lean exhaust: catalytic converters don’t work Also standards for PM, smoke opacity Account for 5% of vehicles, account for 35% visibility reduction; Off-road vehicles emit 2 times PM (regulated in CA from 1996) – Soot from diesel engines is the 2 nd largest contributor to global warming – Relative health risk of diesel exhaust exposure ~ 1. 4 2020/9/15 Aerosol & Particulate Research Lab 30

Heavy-Duty Truck and Bus Engine Emission Standards EPA 1998 Standards HC 1. 3 Heavy-Duty Diesel Truck Engines Urban Bus Engines CO 15. 5 NOx 4. 0 PM 0. 10 0. 05 CA Standards Heavy-Duty Diesel Truck Engines (1994) Urban Bus Engines (1996) NMHC 1. 2 THC 1, 3 1. 3 CO 15. 5 NOx 5. 0 4. 0 PM 0. 10 0. 05 EPA Standards for MY 2004 Option 1 Option 2 2020/9/15 NMHC+NOx 2. 4 2. 5 Aerosol & Particulate Research Lab NMHC n/a 0. 5 31

Octane Rating • A measure of gasoline’s resistance to engine knock (rattling or pinging sound in cylinders due to premature burning) http: //en. wikipedia. org/wiki/ Image: 09 -03 -06 -Octane. jpg – Heptane: 0 – Iso-octane: 100 C C C – Anti-knock agents: Tetraethyl lead (Pb(C 2 H 5)4), highly branched alkanes, aromatics • Research Octane Number (RON): test engine running at 600 rpm; • Motor Octane Number (MON): test engine at 900 rpm Displayed as averaged value: (RON+MON)/2 2020/9/15 Aerosol & Particulate Research Lab 32

Octane Rating • A higher octane rating allows an engine to use a compression ratio of, 12 -to-one instead of a more usual ten-to-one. The greater the compression, the higher the temperature within the combustion chamber. And the higher the temperature, the greater thermal efficiency and power produced. • In the fuel test, the compression is raised until the engine begins to “knock”—ie, the fuel in the cylinder ceases to burn smoothly and instead detonates before it can be ignited by the spark plug. The cylinder pressure at which this occurs is then compared with that achieved while the engine is running on a reference fuel (a mixture of iso-octane and n-heptane). The ratio of the two pressures provides the RON of the fuel in question. • MON test uses more real-world conditions, the MON rating is typically eight to ten points lower than the equivalent RON figure 2020/9/15 33

Emission Control • Engine design, vehicle shape, tire friction • Fuel composition – Octane rating, oxygenated fuel – Fuel desulfurization • Alternative fuel – natural gas, liquefied petroleum gas, methanol, ethanol , bio-diesel, hydrogen 2020/9/15 • Transportation control – Regulatory steps, public transportation, economic incentive • Regulation: Inspection • Add-on control • Alternative power generation – Solar, Electrical, Fuel Cell, Hybrid Aerosol & Particulate Research Lab 34

Vehicle Shape: Aerodynamic Cd 0. 024 0. 031 0. 18 0. 19 0. 25 0. 26 0. 29 0. 57 1. 0 -1. 3 Object F 4 Phantom fighter jet Boeing 787 Boeing 747 Mercedes-Benz T 80 GM EV 1 Honda Insight 2008 Toyota Prius 2004 Honda Accord 2003 Hummer H 2 Dr. Wu (upright position) http: //en. wikipedia. org/wiki/Drag_coefficient 2020/9/15 Aerosol & Particulate Research Lab Asif Faiz et al. , 1996, Air Pollution from Motor Vehicles 35

Tire Friction • Proper tire inflation • Tire rolling resistance: 20% of energy to move the vehicle (4% of world wide CO 2 emission) – Lower rolling resistance for better fuel economy – Safety concern: wet-road grip – Noise • “Green tires” based on silica reduced rolling resistance 30% compared to carbon-black based conventional tires. – Solid rubber tire: 30 kg/ton pneumatic tires 25 kg/ton Tire cord construction 20 kg/ton radial tires (carbon based) 15 kg/ton 2020/9/15 Aerosol & Particulate Research Lab 36

Oxygenated Fuel & Fuel Desulfurization • Oxygenated fuel: mainly ethanol, (MTBE) – Oxygen content in the fuel improves oxidation and results in less CO • Fuel Desulfurization – S poisons catalyst in catalytic converter – SO 2 emission – Gasoline sulfur: 80 ppm per gallon cap in US (delays in Rocky Mountain area); 30 ppm for CA; 10 ppm for EU – Diesel sulfur: 15 ppm 2020/9/15 Aerosol & Particulate Research Lab 37

Alternative Fuel • Natural Gas (mainly CH 4 ; Octane rating 120) & Liquefied Petroleum Gas (LPG; C 3 H 8 and C 4 H 10; Octane rating 105) – Similar energy density per unit mass (not volume) to gasoline but requires compression or refrigeration to maintain them in the liquid phase – 50% less CO and VOCs – No photochemically active VOCs and no air toxics such as http: //en. wikipedia. org/wiki/ benzene Liquefied_petroleum_gas – Issues: onboard fuel storage; handling and refueling • Methanol (CH 3 OH; Octane rating 112) – Low photochemical activity; relative inexpensive – Lower energy density per unit mass (40% of gasoline): shorter driving distance and more frequent refueling – Handling: dissolve rubber; toxic 2020/9/15 Aerosol & Particulate Research Lab 38

Ethanol as an Alternative Fuel • E 85 – blend of 85% ethanol and 15% gasoline – Requires flexible-fuel vehicles (9. 3 million on the road in 2010 in US; same price as regular vehicle) – 2423 stations in US as of Oct/2010 (tax credit for retrofit) • Production – Mainly made from corn in US (current capacity accounts for 3% www. mnsu. edu/news/read. php? id=old-1149701286 gasoline consumption) – Federal subsidy – Research on biomass conversion: cellulosic technology – Mainly from sugarcane in Brazil 2020/9/15 Aerosol & Particulate Research Lab 39

Bio-diesel • Non-petroleum-based diesel fuel consisting of short chain alkyl (methyl or ethyl) esters, made by transesterification of vegetable oil or animal fat (tallow), which can be used (alone, or blended) in unmodified dieselengine vehicles • Transeterification: separate the fatty acids from the glycerol by replacing the glycerol with short linear alcohols; typically requires liquid catalyst • Distinguished from the straight vegetable oil (SVO) used (alone, or blended) as fuels in some converted diesel vehicles • Advantages: reduction in greenhouse gases; no sulfur; better lubricity • Disadvantages: slightly lower energy density; may contain water; cloud point (gelling) higher the petroleum diesel; by-product glycerol; more expensive • Emissions (B 20): PM HC CO NOx 10% 21% 11% 2% • Algae as a feedstock 2020/9/15 http: //en. wikipedia. org/wiki/Biodiesel Aerosol & Particulate Research Lab 40

Traffic Congestion • In 2007, $87. 2 billion drain on US economy, including – 2. 8 billion gallons of fuel – 4. 2 billion lost hours Annual extra time on the roads Rank Metro area Hours 1 Los Angeles 72 2 San Francisco 60 2 2 8 11 Washington, DC Atlanta Orlando Miami 60 60 54 50 Data provided by Texas Transportation Institute, http: //mobility. tamu. edu/ums/ 2020/9/15 Aerosol & Particulate Research Lab 41

Add-on Control: Catalytic Converter (Gasoline) Pt, Pd Two-way Bloomfield, L. , Scientific America, 2001 2020/9/15 Aerosol & Particulate Research Lab 42

Pt, Rd Three-way 2020/9/15 Aerosol & Particulate Research Lab 43

Trade-off Work in rich environment; temperature sensitive 2020/9/15 Aerosol & Particulate Research Lab 44

Older model Newer Model (1980’s in US) 2020/9/15 O 2 for lean environment Aerosol & Particulate Research Lab 45

Diesel Emission Control • Diesel PM Filter: Block Flow Filter http: //www. epa. gov/nonroad-diesel/2004 fr/pmfilters. htm http: //www. epa. gov/cleanschoolbus/images/pmfilter. jpg Lean NO catalyst: Zeolite catalyst to reduce NO Combined with lean-burn engine http: //www. sino-filter. cn/admin/upfile/2009530203359. jpg 2020/9/15 Aerosol & Particulate Research Lab 46

Electric Car Thomas Edison and an electric car in 1913 (National Museum of American History) • First electric car in 1835 by Professor Sibrandus Stratingh of Groningen, Netherlands • First battery powered electric car in 1881 by Camille Faure in France • Lost market to ICE circa 1910 • Government backed promotion (tax credit) revived electric car Who killed the electric car (EV 1)? http: //www. pbs. org/now/shows/223/ Plug-In: uses a wall socket at night to charge and relies on an electric motor to go many miles before sipping any gasoline – good for shortdistance driving in cities 2020/9/15 Aerosol & Particulate Research Lab 47

Electric Car 2011 Nissan Leaf • First 5 -door family car • Li ion battery: 100 miles on a single charge • Charging dock (220 V): 8 hr. 80% recharge in 30 min Cheaper to run per mile than gasoline http: //money. cnn. com/2010/11/09/autos/electric_car_ben efits/index. htm • First (2008) highway capable sedan in constant production • Li ion battery: 245 miles on a single charge • Charging dock (220 v): 3. 5 hrs. 80% repaid recharge in 30 min 2020/9/15 2010 Tesla Roadster tesla‑electric‑car. jpg Aerosol & Particulate Research Lab 48

Hybrid Electric Vehicle • Use 2 sources of motive energy: combustion of gasoline (Internal Combustion Engine) & electrical energy (Electric Motor energized by a Battery) – ICE for highway driving – EM provides added power during hill climbs, acceleration, and other periods of high demand • Regenerative Braking: converts some of the kinetic energy into electric energy; electric motor becomes a generator for battery • Also available for heavy-duty hybrid vehicles (diesel-electric) http: //www. nrel. gov/vehiclesandfuels/ahhps/ 2020/9/15 http: //gm-volt. com Automobile. Honda. com http: //1 st-in-hybrid. com/. . . /07/volvo-hybrid-truck. jpg Aerosol & Particulate Research Lab 49

Advantages of Hybrid Electrics • high performance Fuel economy • long-range capacities Lower emissions • high fuel efficiency 2007 Ford Focus 2007 Toyota Prius MPG(city) 27 MPG(city) 51 MPG(highway) 37 MPG(highway) 60 2007 Honda Hybrid MPG(city) 49 MPG(highway) 51 Plug-in Hybrid: • Lithium ion battery • Charging time: 10 hr on 120 V, 4 hrs on 240 V Cost: federal and state purchase incentives Driving privileges 2020/9/15 Aerosol & Particulate Research Lab 50

Fuel Cell Operation http: //en. wikipedia. org/wiki/Fuel_cell http: //www 1. eere. energy. gov/hydrogenandfuelcells/ 2020/9/15 Aerosol & Particulate Research Lab 51

• University of Florida Fuel Cell Research Lab H 2 source: • H 2 (gas, liquid, solid hydride) – Converted from other energy sources (coal, solar, wind) • Methanol (CH 3 OH) • Gasoline Limitation of H 2 fuel • • 2020/9/15 Pipelines needed to convey hydrogen fuel not currently in place Retail fueling facilities must be placed throughout Danger of H 2 explosion (although gasoline explosion is also dangerous) Requires construction of hydrogen production facilities Aerosol & Particulate Research Lab 52

BP-Praxair H 2 Station Hydrogen Fueling Station Washington, DC (1 st in US) 74 stations in 23 states as of Nov 09; 43 planned 4 stations in FL Honda solar-powered water electrolyzing H 2 station www. hydrogenassociation. org/. . . /bp. Station. jpg H 2 fuel station in Iceland http: //www. cnn. com/2007/TECH/science /09/18/driving. iceland/index. html http: //green. autoblog. com 2020/9/15 Aerosol & Particulate Research Lab 53

Methanol as an Alternative to Hydrogen • Some production facilities already exist • Distribution facilities can accommodate with slight modifications • Dispensing facilities can accommodate with only slight modifications • Currently there is an abundance of methanol Steam Reforming Equilibrium Reaction at 1 atm and 300 o. C: CH 3 OH + 1. 5 H 2 O 2. 896 H 2 + 0. 896 CO 2 + 0. 104 CO + 0. 603 H 2 O Catalyzed by Phosphoric Acid Membrane (PAM) 2020/9/15 Aerosol & Particulate Research Lab 54

Evaporative Loss – Refrigerant • CFC (Chlorofluorocarbons) – Ozone depleting chemical phased out starting from 1987 Montreal Protocol • Replacement: HCFCs (Hydrochlorofluorocarbons) HFCs (Hydrofluorocarbons) • Further ban on global warming gases Compound CO 2 CFC-12 HCFC HFC-134 a GWP 1 8500 1300 -7000 1300 http: //www. epa. gov/ozone/ods. html http: //pubs. acs. org/isubscribe/journals/cen/83/i 1 8/html/8318 gov 2. html? em. From=em. Login – EU: HFC-134 a banned in new cars in 2011; any other fluorinated gas with a GWP > 150 in all vehicles in 2017 – US: HCFCs in new appliances restricted from 2010 • Replacement: nontoxic and nonflammable – CO 2 (requires new systems); DP-1 (GWP-40); Fluid H (GWP-10) 2020/9/15 Aerosol & Particulate Research Lab 55

http: //www. youtube. com/watch? v= W 6 d. Is. C_e. GBI 2020/9/15 Aerosol & Particulate Research Lab 56