Development of vehicle emission factors using PEMS

Transcription

1 Development of vehicle emission factors using PEMS Dr. Carol Wong Senior Environmental Protection Officer Environmental Protection Department Hong Kong September, 2013

2 Outline Background, Objective & Current Status PEMS test procedures Vehicle info and test set up PEMS data analysis Conclusion 2

3 Background & Objectives EPD has adapted EMFAC developed by California Air Resources Board (CARB) into Hong Kong Have been using US vehicle emission data in EMFAC-HK calibrated by our PEMS test data Traffic conditions at busy corridors Being a metropolitan city, HK is very different from US or Europe Wish to replace these emission data in EMFAC-HK by local on-board emission data and also develop a microscopic model

4 Various PEMS being used in HK Analyzers SEMTECH-DS (7 units) Measurement CO, CO2, NO, NO2, THC SEMTECH-Low CO analyzer SEMTECH-Filter Sys. SEMTECH-ECOSTAR (1 unit) (not yet working) NO, NO2, PM A&D portable FTIR (1 unit) N2O, NH3, CO, CO2, NO, NO2, & various hydrocarbon species SECTECH-Low CO analyzers (2 units) CO in low concentration A&D THC/Low CO analyzer (1 unit) (not yet working) CO in low concentration and THC FTIR SEMTECH- DS THC/low CO analyzer SEMTECH-SAMPS SEMTECH-SAMPS (5 units) & SEMTECH-Filter System (3 units) PM AVL M.O.V.E. PM PEMS (2 units) Real time PM Micro-soot sensor Gravimetric filter module

5 No. of Vehicles Current Status measuring real-world vehicular emissions using PEMS since 2008 Collected about 14 million seconds of measurement data Tested about 180 vehicles Test each vehicle for all its business hours Emission standards: from pre-euro to Euro V Vehicles tested until end August, Vehicle Types

6 Vehicles Explored up to end Aug., 2013 Vehicle Class Fuel Type Pre- Euro Emission Standard Euro I Euro II Euro III Euro IV Euro V Cars Petrol Taxis LPG Mini buses Total LPG Diesel Truck 5.5 t Diesel Truck > 5.5t Diesel School Bus Diesel Single Deck Coaches Double Deck Buses* Diesel Diesel Total * Double deck buses are retrofitted with diesel particulate filter (DPF). 6

7 Euro III, IV & V Diesel Vehicles Explored up to end Aug., 2013 Euro III Euro IV Euro V Vehicle Class Nil DOC DOC & EGR EGR DPF DOC & EGR POC & DOC, EGR DPF DPF & EGR SCR* DOC & EGR DPF & EGR SCR Mini buses 2 1 Truck <= 5.5 t Truck > 5.5t School Bus 2 Single Deck Coaches Double Deck Buses (w DPF) 2 Total *The vehicle may also be fitted with DOC 7

8 Outline Background, Objective & Current Status PEMS test procedures Vehicle info and test set up PEMS data analysis Conclusion 8

9 Test procedures Follow most stringent testing requirements: ISO16183 US CFR 1065 Subpart J EU JRC s Guide for the preparation and the execution of emission road tests on heavy-duty vehicles 9

10 Test procedures Perform zero every hour and audit of the gas analyzers every three hours Implement duplication of measurements principle Analyze 2-3 fuel samples from each test vehicle s fuel tank 10

11 On-Road Testing Example: SCR coach On-road testing of an EURO IV coach (w/ SCR) Professional bus drivers Driving on a pre-determined routes as well as following a similar vehicle 50-60% of maximum payload Traffic are captured by video camera mounted in front of the bus Both gaseous pollutants and PM are collected PEMS used SEMTECH-DS, FTIR, and M.O.V.E. PM PEMS Soot concentration from AVL PM PEMS Emission data from SCR vehicle testing

12 Outline Background, Objective & Current Status PEMS test procedures Vehicle info and test set up PEMS data analysis Conclusion 12

13 Example: SCR retrofit program on 3 Double Deck Buses (FBDD) with DPF Make Eng Model Dennis Trident Euro III ISMe 335 Euro III/ Volvo Olympian Euro II D10A 245 Dennis Trident Euro II M11-305E21 Eng Capacity 10.8 litre 9.6 litre 10.8 litre Emi Standard Euro III Euro II Euro II First Reg. Date 1 Aug Mar Sept 1998 Engine rated power Engine rated torque RPM RPM RPM RPM RPM RPM GVW 23.5 tonnes tonnes 23.1 tonnes Loaded Weight 19.0 tonnes 19.7 tonnes 19.4 tonnes After treat. device DPF DPF DPF 13

14 Test Set-up 14

15 Installation - 1 Speedometer Remote diluter Heated line Exhaust flow meter Connecting pipes from tailpipe to PEMS GPS, RH & temperature sensors Heated line for sampling before SCR SCR 15 15

16 Installation - 2 Microdilution system (MPS) Filter system FTIR SEMTECH-DS Heated line SEMTECH- DS

17 Fixed Route Maps 17

18 Outline Background, Objective & Current Status PEMS test procedures Vehicle info and test set up PEMS data analysis Conclusion 18

19 3 FBDD retrofitted with DPF+SCR : Trip Avg Speed and Max Speed urban highway 19

20 Euro II Dennis Trident FBDD w DPF: NOx Real-time snapshot Base case (with DPF) After retrofitted with SCR Measured at the position before SCR Measured at the position after SCR 20

21 Euro III Dennis Trident FBDD w DPF: NOx Real-time snapshot Base case (with DPF) After DPF removal and retrofitted with SCR+DPF Measured at the position before SCR+DPF Measured at the position after SCR+DPF 21

22 Data Pre-Processing (Gaseous) 22

23 Data QA/QC Checks In order to perform the QA/QC task, a variety of plots were created to expose outlying, unusual, or inaccurate data Exhaust flowrate distributions by vehicle Exhaust concentration distributions by vehicle Raw vs corrected exhaust concentrations by vehicle Maximum and mean exhaust concentrations by test, displayed together by vehicle Exhaust concentrations vs time by test VSP bin frequency and VSP binned emission mass rates by vehicle data flags in SAS were used to draw attention to values that lie outside of expected ranges

24 Automatic Error detection Checking and calibrating speedometer reading by GPS 1) Select the good GPS data by extracting Horizontal dilution of ratio < 1.3 2) Linear regression with Speedometer data to measure R2 and slope 3) Use the slope to calibrate speedometer readings Partial speedometer error Speedometer error Normal data

25 Automatic Error detection Abnormal jumps in exh. temp. Jumps in THC readings Outliers in NO readings Abnormally long negative readings Cold start Drift in THC High THC peaks

26 QA/QC results Heavy diesel truck > 15 t: THC emission factors Before data cleansing After data cleansing Light diesel truck <= 5.5 t: NOx emission factors

27 NOx emission rates (g/min) Dennis Trident Euro III bus retrofitted with DPF Baseline

28 NOx emission rates (g/min) Dennis Trident Euro III bus retrofitted with DPF 1 month after retrofitted with SCR+DPF

29 NOx emission factors (g/km) Volvo Olympian Euro II bus retrofitted with DPF Baseline 29

30 Exhaust temp oc NOx emission factors (g/km) Volvo Olympian Euro II bus retrofitted with DPF and SCR 1 month after SCR retrofit 30

31 Exhaust temp oc NOx emissions in g/km Volvo Olympian Euro II bus retrofitted with DPF and SCR, 1 month after SCR retrofit with traffic jam at Mongkok 31

32 Exhaust temp oc NOx emission factors (g/km) Volvo Olympian Euro II bus retrofitted with DPF and SCR, 6 month after SCR with low exhaust temp (<=200oC) 32

33 NO emissions of post-scr at 6 months after SCR retrofit (blue triangles) are close to base line emissions (red triangles) and highly fluctuating. Description NO NO2 NOx %reduction at 1 month after SCR retrofit vs. baseline 73-85% 81-92% 74-86% %reduction at 6 months after SCR retrofit vs. baseline % 70-94% -2-56% %reduction at 9 months after SCR retrofit vs. baseline 54-69% 67-80% 57-71% 37

34 One trip for this FBDD has urea shortage. The NO & NO2 reductions are particularly low. Description NO NO2 NOx %reduction at 1 month after SCR retrofit vs. baseline 55-65% 35-54% 56-63% %reduction at 6 months after SCR retrofit vs. baseline 60-72% 68-77% 62-72% %reduction at 9 months after SCR retrofit vs. baseline (Excluding urea shortage trip) 64-70% 61 69% (with one trip 35%) 64 68% 38

35 The NO reductions are very small at 6 months after the retrofit because SCR had broken down due to uncontrolled regeneration (green triangles) Description NO NO2 NOx %reduction at 1 month after SCR retrofit vs. baseline %reduction at 6 months after SCR retrofit vs. baseline 78-93% 57-73% 77-81% 25-37% 68-71% 41-49% 39

36 PM Emission Factors The color is white even though PM emissions are high Filter for other high emitting vehicle

37 We have the following criteria: abs(intercept/ max. sample flow) <= 5% (c.f. ISO 16183: <= 2%) Std error/mean <= 10% (c.f. CFR1065 <= 3.5%) Std error/max. <= 5% (ISO16183: <= 5%) R2 >0.95 (c.f. ISO 16183: >0.95) Normal Situation excessive idling Test trips with excessive idling can also introduce significant PM error 41

38 PM results for SCR Euro IV coaches > 15 t 42

39 Estimated PM (g/s) Real time PM AVL PM PEMS is capable to measure real time soot conc., and then estimate real time PM emissions from soot, CO, CO2, THC conc. These real time PM emissions are then calibrated by PM mass collected in the on-board filter. These high PM emissions are due to hard accelerations when the vehicle started. Time (s)

40 PM emissions with Spd and CO High PM emission usually accompanied by hard accelerations mdot_pm [g/s] Velocity [km/h] Time [s] PM emission strongly correlated in time with CO emissions mdot_pm [g/s] CO [%] Time [s] -0.6

41 Outline Background, Objective & Current Status PEMS test procedures Vehicle info and test set up PEMS data analysis Conclusion 45

42 Conclusion The emission factors derived from the on-board measurement data will be used in EMFAC-HK They will also be used in a microscopic model for more refined traffic conditions 46