Pokharel, Sajal S.

Slott, Robert

Stedman, Donald H.

English

University of Denver

University of Denver Digital Commons @ DU Fuel Efficiency Automobile Test Publications Fuel Efficiency Automobile Test Data Repository 2001 Interpreting Remote Sensing NOx Measurements Robert Slott Donald H. Stedman Sajal S. Pokharel Follow this and additional works at: https://digitalcommons.du.edu/feat_publications  Part of the Environmental Chemistry Commons Interpreting Remote SensingNOx MeasurementsRobert Slott, Consultant,Donald Stedman and Saj Pokharel, Universityof DenverFall Fuels & Lubricants MeetingSan Antonio, TX, September 24-27, 2001Presented May 9, 2002Paper # 2001-01-3640AcknowledgementsProject sponsor: Coordinating Research CouncilhData collected by Prof. Donald Stedman’sgroup at University of DenverhReports available at http://www.crcao.comhData at http://www.feat.biochem.du.edu/hVINs decoded by Eastern Research GroupPaper # 2001-01-3640Analyzing Vehicle Tailpipe EmissionshFleet emissions increase with agehPossibility of sampling biashEmissions higher when catalyst coldhEmissions depend on loadhEmissions may vary when vehicles measuredunder same conditions at different timeshDifferent model years & vehicle types havedifferent standards & control technologiesPaper # 2001-01-3640CRC E23 ProjectMonitor how on-road vehicle tailpipe emissions(HC, CO, NOx) are changing with timehUse remote sensinghMeasurements in at least 4 citieshChicago, Phoenix, Los Angeles, DenverhLarge number (20,000) of measurements atsame time of the year at each locationhUniform QC/QA and data reportingPaper # 2001-01-3640Remote SensingMeasures concentrations of CO, HC, NO, CO2in automobile exhausthAccuratehMeasured over ~ ½ secondhVehicle identified by video frame of licenseplate matched to registration recordshRelated to grams/gallon, not grams/milehLimited numbers of suitable sitesPaper # 2001-01-3640Calculate Vehicle LoadVehicle Load estimated as Vehicle SpecificPower (VSP) fromhSpeed, Acceleration, and Road GradehTypical Values of VSPhNo Load = 0 kW/tonnehDeceleration = <0 kW/tonnehASM Test = 5 to 9 kW/tonnehUpper limit of FTP = 23 kW/tonnePaper # 2001-01-3640NO Vehicle EmissionsNOx emissions very sensitive to VSP (load)under typical driving conditionshNOx emissions vs VSP for individual vehicleshFrom low VSP ~ 0 kW/tonne, where NOx is low,hNOx increases until VSP = 15 to 20 kW/tonnehThen decreases if fuel enrichment employedhAnd increases again at higher VSPPaper # 2001-01-3640Three Phoenix Remote Sensing SiteshIn 1998, a high speed, low load site gave lowpercent valid readings due to small exhaust plumes.hIn 1999, two sites were used. These were atdifferent positions on the same on-ramp.hSite 1: Free flowing traffic, no reason to rush;Trucks observed to dawdle, cars moved faster.hSite 2: Entry to highway, vehicles accelerate.hTwo sites measured on different days.hSame model year distribution, similar fleetPaper # 2001-01-3640Phoenix 1999Sites at uphillexit ramp fromHwy 202 / SkyHarbor Blvd.Westbound toHwy 143Southbound,Site 2: at top oframp as shown,Site 1: ¼ waydown the ramp.%NO and VSPPhoenix 1999Site 1 on topSite 2 at bottomAverage %NO& Number ofvehiclesmeasuredon y-axis,VSP on x-axis.%NO and VSP, Phoenix  1999,  Si te  100.010.020.030.040.05< 0 0 5 10 15 20 25 >30VSP, kW /tonne%NO03006009001,2001,500Number of Vehicles %NON%NO and VSP, Phoenix 1999, Site 200.030.060.09< 0 0 5 10 15 20 25 >30VSP, kW/tonne%NO0100020003000Number of Vehicles%NONNOx Emissions in PhoenixhPhoenix 99 NOx measurements appear to beindependent of VSP at Site 2 (high load site).h%NO is a strong function of vehicle age and loadinteracted with vehicle age at Site 2.hFleet NO emissions analysis needs to take intoaccount age, load, and vehicle type.hData from three Phoenix Sites binned intoh5 kW/tonne bins (Bin 5 = VSP from 2.5 to 7.5)h5 year age bins (Bin 3 years = 1 to 5 years)hanalysis on CARS as defined in the VIN.Paper # 2001-01-3640 % TrucksPhoenix 1999Site 1 on topSite 2 bottomIn both sitesvehicle typeinteracts withVSP.%Trucks on they-axisVSP on x-axis.±1.96*Std. Err.±1.00*Std. Err.MeanSite 1: Trucks 35% OverallVSP BIN, kW/tonneAll Cars50/50 Cars/TrucksAll Trucks0 10 20 30 40 50±1.96*Std. Err.±1.00*Std. Err.MeanSite 2: Trucks 32% OverallVSP BIN, kW/tonneAll Cars50/50 Cars/TrucksAll Trucks0 10 20 30 40 50Model year vs VSP, Phoenix 99 SitesVehicle age is much moredependent on load at Site 2.±1.96*Std. Err.±1.00*Std. Err.MeanVSP BIN, kW/tonneAverage Vehicle Model YearSITE: 19293949596970 10 20 30SITE: 20 10 20 30Phoenix Site Comparisons, Cars Onlyl Which Phoenix site in 1999 was giving a typical NOvs VSP relationship when binned for age as well asVSP?l Comparing the two Phoenix 99 Sites with thePhoenix 98 Site, Site 2 in Phoenix 99 was moresimilar to Phoenix 98 Site than Site 1.l [Phoenix 98 Site] and [Phoenix 99 Site 2] aresimilar in their NO vs VSP relationship toChicago 99 remote sensing measurements.Phoenix 1998 & 1999, Cars Only0.000.020.040.060.080.100.120.140.160 5 10 15 20 25 30 35 40VSP kW/tonne%NO3 yrs PHX988 yrs PHX9813 yrs PHX983 yrs PHX99 Site18 yrs PHX99 Site113 yrs PHX99 Site13 yrs PHX99 Site28 yrs PHX99 Site213 yrs PHX99 Site2Phoenix 98-99 & Chicago 99, Cars0.000.020.040.060.080.100.120.140.16-5 0 5 10 15 20 25 30 35 40VSP%NO3 yrs PHX988 yrs PHX9813 yrs PHX983 yrs PHX99 Site28 yrs PHX99 Site213 yrs PHX99 Site213 yrs Chicago8 yrs Chicago3 yrs ChicagoChicagoRemoteSensing SiteOn-ramp fromAlgonquin Rd.to eastboundI-290(S.H. 53)in northwestChicagoChicago 1997-1999, Cars0.000.020.040.060.080.100.120.14-10 -5 0 5 10 15 20 25 30VSP kW/tonne%NO1997 3 yrs1997 8 yrs1997 13 yrs1998 3 yrs1998 8 yrs1998 13 yrs1999 3 yrs1999 8 yrs1999 13 yrsAdjusting %NO to gpm NOl In Chicago, the change of %NO vs VSP bymeasurement year from 1997 to 1999 was smallcompared to the change of %NO seen in any ofthese years due to vehicle age.l Combined %NO data by vehicle age (from 1997,1998, and 1999 measurements) was converted tograms/gallon, and then, using a correlation basedon engine size and 1997 vehicles’ fuel economy, tograms/mile (gpm).Gram/mile (gpm) for CARS 1997Correlation between engine size and mpg weighted vehicles based onfrequency they were seen in 1997 remote sensing measurements.Exponential Model without GEO Metro, 1997 Carsy=20.0+exp(3.97-1.03*x); R = 0.91Engine Size, LitersOverall Miles per Gallon10203040500.5 1.5 2.5 3.5 4.5 5.5NO gpm for 3, 8, 13 year Age BinsCRC E23 IL97-99, gpm NO, Cars0.00.20.40.60.81.01.21.41.61.82.0-5 0 5 10 15 20VSP BIN, kW/tonnegpm NO 3813Model vs Data in gpm NOxgpm NO = (0.17*[AGE_BIN] - 0.03)*EXP(0.37[VSP_BIN])Model for gpm NO for CarsYear Measured 1997, 1998, 1999; Age of Cars 3, 8, 13 yrs.; VSP 0, 5, 10, 15 kW/tonney = 1.04x - 0.02R2 = 0.950.00.51.01.52.02.50.0 0.5 1.0 1.5 2.0 2.5Data, gpm NOModelModeled gpm NOx in Chicagol Chicago 97-99 remote sensing NO emissions,binned by load and vehicle age, and converted togpm using average fuel economy, can be modeledfrom VSP = 0 to 15 kW/tonne, and age = 1 to 15years, by a equation based on age and VSP.l Two points off the line are due to older vehicles(measured in 97 & 98) at 15 kW/tonne.  Thiscould  be explained if some of these older vehicleshave gone into fuel enrichment at 15 kW/tonne,suppressing NO formation.Status of E23 Measurements# Not E23 Project but measurements conductedunder E23 protocol and available for analysis

Interpreting Remote Sensing NOx Measurements (Presentation)

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Interpreting Remote Sensing NOx Measurements (Presentation)

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