Vehicle Emissions Measurement

Transcription

1 Vehicle Emissions Measurement Nairobi, Kenya 1 st /04/2015 Andriannah Mbandi Stockholm Environment Institute University of York andriannah.mbandi@york.ac.uk

2 Combustion process Ambient air quality standards Combustion: Ideal, Real Combustion gases & particulates Petrol or diesel? Units of measurement Vehicle emission legislation Vehicle technology Vehicle fleet in Kenya Inspection & Maintenance Conclusion

3 Combustion process Oxygen Nitrogen Water Vapor Fuel: Petrol, Diesel

4 Ambient air quality standards SA National Environmental Management: Air quality Act No.39 of 2004: National Ambient air quality standards, 2009 Compound Limit Exposure CO 30 mg/m 3 1 hour Pb 0.5µg/m 3 Annual NO µg/m 3 1 hour O µg/m 3 8 hours PM µg/m 3 * Annual PM µg/m 3** Annual SO µg/m 3 10 min *Reducing to 40µg/m 3 in Jan/2015 ** Reducing to 20µg/m3 in Jan/2016

5 Combustion process Ideal Combustion λ = 1 O 2 O 2 Fuel Fuel Fuel CO2 CO2 CO2 O 2

6 Combustion process Lean Mixture λ > 1 O 2 O 2 O 2 Fuel CO2 O 2 Fuel Fuel CO2 CO2 O 2 O 2 O 2 Rich Mixture λ < 1 O 2 Fuel Fuel Fuel CO2 CO2 CO O Unburnt Fuel O 2

7 Combustion gas: oxygen (O 2 ) O 2 levels inverse of CO levelswithout air injection system Lean Mixture: O 2 Rich Mixture: O 2 O 2 content increases sharply as λ>1

8 Combustion gas: carbon dioxide (CO 2 ) Result of complete combustion Overall combustion and catalytic converter efficiency Not a pass or fail gas Global Greenhouse gas emissions data CO 2 : 12-16% clickcarparts, 2014 IPCC, 2007

9 Combustion gas: carbon monoxide (CO) Incomplete combustion Excess fuel = rich mixture Partially burnt fuel Catalytic converter requires air/fuel ratio to vary lean to rich Pre-catalytic converter: CO<1.5% After catalytic converter: CO~0% Feedback carburetted engine ran rich at idle: CO~9%

10 Combustion gas: hydrocarbons (HC) Unburned fuel due to incomplete combustion All engines produce HC: Pre-catalytic converter: ppm After catalytic converter: ~0 ppm Wasted fuel 1% partially burnt fuel produce 200 ppm HC

11 Combustion gas: oxides of nitrogen (NO X ) Primary contributor of ozone Formed under high T & P: not formed at idle or light loads Lean mixture at high T: excess O 2 molecules combine to form NO X Exhaust gas recirculation(egr): O 2 and T

12 Combustion gas: oxides of sulphur (SO X ) High sulphur (S) content in fuel Bilfinger, 2014 Reduction in S content reduces emissions in exhaust Marine engines have higher contribution

13 Combustion particles-particulate matter (PM) Formed in combustion cylinder and in the exhaust system of the vehicle. Mostly attributable to heavy duty diesel vehicles ARB, 2009 Mix (condensed) liquid & solid- Organic or Inorganic Sulphates Nitrates Ammonia Sodium chloride Black Carbon Mineral dust Water

14 Petrol Engine Petrol and Diesel Engines Diesel Engine Spark Ignition Fuel/Air premixed before compression Lower efficiency & Lighter AFR:14.7 (predetermined) Emissions: More fuel, >CO 2, less NO X and low PM Compression Ignition Fuel/Air not premixed Higher efficiency-high compression ratio & Heavier AFR: /1 (air injected not controlled) Emissions: less fuel, <CO 2, >NO X Higher PM Pollutants: CO, HC, NO X Pollutants: NO X, PM, Smoke

15 Units of measurement Gases O 2 : % CO 2 : % CO: % HC: ppm NO X : ppm PM Particulate Mass (µg/m3) Particulate Number (#/km) Smoke: Opacity: % Smoke density: m -1 Engine: λ, RPM, T, P

16 Vehicle Emission Legislation Emission limits Standards Test cycles Regulations Test and Measurement Specifications Result Calculation and reporting specifications AVL, 2014

17 EU Emission legislation Light Duty Heavy Duty AVL, 2014

18 Vehicle technology and fuel quality DOC TWC DPF ECU EGR SCR ICCT, 2012

19 Selective Catalytic Reduction (SCR) Diesel engine control emissions technology Reduces NOx (~90%) using urea as a reductant within a catalyst system End product: N 2, H 2 O and small CO 2 factsaboutscr, Way Catalytic converter (TWC) Petrol engine control emissions technology Most vehicles sold have TWC use of TWCs with an oxygen sensorbased closed-loop fuel delivery system Simultaneous conversion of the three criteria pollutants-hc, CO, and NOx clickcarparts, 2014

20 Use of PEMS to measure gases & PM GPS & weather probe Exhaust Flow Meter (EFM) Flow tube Heated sample line Weighing Gas bench: CO/CO2 (NDIR) NOx (NDUV), THC (FID) power supply 110 VAC, 220 VAC or 12 VDC Exhaust sample

21 Vehicle fleet in Kenya Base Emission Standards on fleet characterization!! Vehicles from neighbouring countries Test: Road side testing PEMS Vehicle Imports: Test: Mechanical & Emissions Test Centres Existing Vehicle Fleet Emissions Inventories (g/km) No. of vehicles Vehicle types Age of vehicle Distance travelled Fuel Test: Safety & Emissions I/M Centres Scrappage: Test: Mechanical & Emissions Test Centres Vehicles to neighbouring countries Test: Road side testing PEMS

22 Inspection & Maintenance I/M Standards-based on distribution of emissions levels Set Inspection fees to support I/M programs Phased Approach: Learning Adaptation Capacity building I/M requirement for operating vehicle + Linked to vehicle registration Capacity building for all actors in I/M Test CO HC NO X PM Smoke Cost Time Where? Idle Test χ χ low fast UK, EU 2-Speed idle Test χ χ low fast UK, EU Snap or Free acceleration Test χ low fast California, SA IM 240 χ χ χ High Medium USA Full load χ χ χ χ χ High Medium EU, USA, Japan

23 EU Emission I/M Standards Source: EU directives 96/96 EC and 2001/9/EC Year CO standard (%) Lambda (λ) < Idle > Idle With Catalytic converter Idle Test (Petrol) < λ < speed idle Year Turbocharged Naturally aspirant Test (Diesel) < > m m -1 Free acceleration

24 UK Emission MOT standards Year Test Type (Petrol) Pass or Fail All Visual Inspection Visual Black smoke/dense blue >1975 Standard Emissions Gas Analyzer (noncatalyst test) CO :3.5%-4.5% HC: 1200ppm >1992 Basic Emissions Gas Analyzer & EC Fast Idle Normal Idle CO<0.2% HC<200ppm 0.97 < λ <1.03 CO <0.3% Year Turbocharged Opacity (m -1 ) Normal Opacity(m -1 ) Test (Diesel) < Visual Diesel fast pass > Diesel fast pass

25 Decentralized: ~ local car repair garages Test: Vehicle safety Road worthiness Exhaust emissions Age: 3 years old Annual test Cost: Failure: notice & repair Re-test: free or reduced fee (defect/time) Time: min, 2 technicians hicksmotandservice, 2014

26 California Air Resources Board (ARB) Heavy-duty trucks and buses: control excessive smoke emissions & prevent tampering (>6000lb) Test-Society of Automotive Engineers (SAE) J1667 snap acceleration procedure-opacity measurement Test using PEMS Allowable levels of Smoke Opacity All post 1991 or newer engines All pre-1991 engines Must not exceed 40% opacity Must not exceed 55% opacity Periodic Smoke Inspection Program (PSIP) Heavy-Duty Vehicle Inspection Program (HDVIP)

27 Snap acceleration (Free acceleration Test): Opacity SAEJ1667 snap acceleration: RPM recording (Idle/Max) Sensing probe inserted Driver accelerates 3 times with transmission in neutral (to clear loose particles) then repeat 3 times) Applus, 2009

28 South Africa-Cape Town Emission Legislation Air Quality Management by-law 2003, 2010 Vehicles: Compression ignition (Diesel) Dark smoke (2010): Light absorption >=20% BP Hartridge smoke meter Naturally aspirated HSU 50HSU 2.125m m % Turbocharged 66 HSU 56HSU 2.51m m %

29 Oliver, 2014

30 Rwanda-vehicle emissions Air Pollution-N 005/03 (2013) Private cars (1 year) Commercial vehicles (6 months)

31 New technologies: User friendly Maintenance Light Robust Precise Is it fit for purpose? Conclusion Vehicle fleet: age, technology Fuel quality Nation, 2014 R&D, vehicle manufacturers, Bureau of standards