1. Andrea Jungers William McCary Professor Ahmet Selamet ME 5530

2. Overview Background of hydrocarbons Hydrocarbons and pollution Automotive sources of hydrocarbons Hydrocarbon traps of automobiles  Intake – EVAP systems  Exhaust – TWC

3. Types of Hydrocarbons Alkyl Compounds Saturated Alkanes (Paraffins) single bond Unsaturated Alkenes (Olefins) double bond Cyclanes (Napthenes) single bond ring Alkynes (Acetylene) triple bond Aromatics Benzene, Toluene, Xylene Alcohols Methanol, Ethanol Ethers Methyl Ether

4. Pollution VOCs Volatile organic compounds Chemicals containing hydrogen, carbon and possibly other elements Evaporate easily VOCs increase the amount of nitric oxide in the air, which in turn combines with oxygen to produce nitrogen and ozone Ozone is otherwise known as smog at ground level VOCs in the air prevent ozone from breaking down Ozone can react with lung tissue causing inflammation, changes in breathing passages and coughing http://www.epa.ohio.gov/dapc/echeck/whyecheck/healthef.aspx Transportation Transportation is the largest source of air pollution in the United States (http://www.ucsusa.org/clean_vehicles/why-clean-cars/air-pollution-and-health/cars-trucks-air-pollution.html) In the early 20 th blow-by gases were allowed to be exhausted into the atmosphere Positive crankcase ventilation (PCV) was first installed on new cars in the 1960s and it marked the beginnings of the Evaporative Emissions Control Systems (EVAP)

5. Intake Evaporative Emission Control Systems (EVAP) Approximately 20-40% of all HC emissions originate from evaporative sources First form of emission control on a vehicle and often the least expensive Five ways evaporative emissions are produced: 1)Diurnal Evaporation 2)Running losses – Positive Crankcase Ventilation 3)Hot soak 4)Re-fueling 5)Permeation The function of the EVAP system is to block/capture HCs produced from these five sources and prevent their release into the atmosphere PZEV – Partial Zero Emission Vehicle near zero evaporative emissions

6. Positive Crankcase Ventilation (PCV) Fixed Orifice PCV System Meters blowby from crankcase into intake manifold Provides ventilation based on size of orifice valves and intake manifold vacuum Two orifice valves balance strength of vacuum applied to crankcase Variable –Flow PCV Valve Variable-flow PCV valve more accurately matches ventilation flow with blowby production Blowby is typically greatest during high loads A small amount of gases in the combustion chamber escapes past the piston during a compression stroke These gases are called “blowby” gases – unburned HCs make up approximately 70% Closed crankcase ventilation routes blowby gases back into the engine airtake system

7. Evaporative Emission Control Systems (EVAP) http://www.visteon.com/company/features/media/050103index.html

8. First examples of this system used in application is the 2000 Nissan Sentra CA Two HC Trap Catalysts, one under the oil pan and the other under the floor. Process: The first HC Trap begins to capture HC within the exhaust gas until the Close- Coupled TWC is warmed up. The first HC Trap then releases HC and begins conversion. Any HC that were not converted by the first HC Trap will then be caught by the second HC Trap. The second HC Trap finally releases HC and completes conversion. Exhaust Gas Hydrocarbon Trap Systems

9. Three Way Catalyst (TWC) Chemical Reactions Oxidation Reduction Catalyst Structure & Layering

10. Zeolite vs. Hydrocarbon MoleculesZeolite Washcoat Substrate The substrate is generally a monolith, or honeycomb, structure which creates support for the bottom coat. The bottom coat is often zeolite, a porous alumino-sillicate. silicon tetra-oxide (SiO 4 ) aluminum tetra-oxide (AlO 4 ) The HC molecules found in exhaust gas range from 0.4-0.7nm while the zeolite molecular size is between 0.5-0.8nm. The top coat, the washcoat, consists of a catalyst from converting HC that released from the zeolite. Hydrocarbon Capture

11. Calculating EfficiencyMeasuring HC Emissions Trapping & Conversion Performance

12. Active vs. Passive System Control Bypass Loop Valve Timing & Positions Valve 1Valve 2Valve 3 Engine Starting ClosedOpen Switch: 60 secOpenClosed Fully HeatedOpen Active Control: Valve System The valve timing is very fast and the bypass loop switches within 60 sec of starting the engine. The first HC trap is heated, and then the valves switch to heat the secondary HC Trap. Passive Control: Hole Drilled in Absorber A small hole increases trapping efficiency of the first HC Trap but increases the light-off time of the second A large hole decreases trapping efficiency of the first HC Trap but decreases the light-off time of the second.

13. Supelcarb ® HC TrapSupelpure ® HC Trap S-Trap: 19 cm × 13 mm Bed Length: 50.2 cm Company: Sigma-Aldrich St. Louis, MO Two Size Options 750 cc : 41.9 cm × 59 mm 120 cc : 28.2 cm × 35 mm Price Range: $100.00 to $500.00 Purchasing Hydrocarbon Traps

14. “Mobile Emissions Catalysts.” BASF.com. http://www.catalysts.basf.com/p02/USWeb- Internet/catalysts/en/content/microsites/catalysts/prods-inds/mobile- emissions/AISHC). 10 Oct 2013. Heck, Ronald M. and Farrauto, Robert J. “Automobile exhaust catalysts.” Elsevier Science B.B. 2001. 443-449. Web. Nishizawa, Kimiyoshi. "The Hydrocarbon Trap." Technologies for Near-Zero-Emission Gasoline-Powered Vehicles. Ed. Fuquan (Frank) Zhao. Warrendale, PA: SAE International, 2007. 269-282. Print. Schager, Martin. “Automotive Evaporative Emissions Systems.” The Technology Interface. Winter 2003. Vol 5. Web. Sullivan, Kevin R. “Emissions Sub System – Evaporative Emission Control System.” http://www.autoshop101.com/. Web. 1998-2013. "Feature Stories." Visteon.com. http://www.visteon.com/company/features/050103.html. Visteon Corporation. 10 Oct. 2013. http://www.ucsusa.org/clean_vehicles/why-clean-cars/air-pollution-and-health/cars- trucks-air-pollution.html http://www.epa.ohio.gov/dapc/echeck/whyecheck/healthef.aspx http://www.sigmaaldrich.com/catalog/product/supelco/22446?lang=en&region=US References