Correlation between Laboratory Emission Measurement … · 1. Background 2. Recent Advancements in PEMS Technology 3. Correlation between PEMS and a Laboratory Emission Measurement
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PEMS: Evolution to Accurate Measurement WET based measurement for better performance
• Direct conversion to mass from exhaust flow without dry to wet correction• Faster response using HOT / WET measurement technique (no cooler)• More accurate real-world CO and CO2 measurement by Heated NDIR• Reliable / accurate NOX measurement by Dual Chemiluminescence (CLD)
Component Detection principle Advantage
NO, NOX Heated Dual-CLD • No dehumidifier (chiller) : fast response• Small size, low sample flow rate
NO2 (Calculated by Dual-CLD) No dehumidifier : no chiller loss of NO2
COHeated NDIR • No dehumidifier : fast response
• Integral H2O measurement for compensationCO2
THC Heated FID• Vacuum sampling for fast response• 190ºC for diesel THC measurement with no
HC hang-up• Compact design
PM Gravimetric filter method and DCS
• Good correlation with laboratory systems• Real-time PM measurement with high
Real concentration at measuring point can be measured by H-NDIR
NDIR with chiller/dehumidifier cannot provide accurate dry to wet base correction during changing water conditions(e.g. Cold Start / Diesel / LNG / CNG)
Pitot flow tubes can now easily be mounted on Dual Exhaust vehicles.
Close Coupled Transducer modules
Improvements for Exhaust Flow• Faster pressure sensor response. = better measurement• New “Water guard” is added to prevent water influence• Colder weather specification (down to 20º F)
Exhaust flow rate signal from pitot tube flowmeter used to control proportional sampling as certification method and calculate real time particle measurement
DCS is a real-time particle sensor, based on diffusion charge principle
DCS signal is calibrated to actual PM mass post-testing using the filter based method.
The use of the diffusion screens to eliminate PM mass over-reading during DPF regeneration
PM mass measured by filter using a portable exhaustflow rate proportional partial flow dilution system
Real time measurementGravimetric Method
This method is approved by EPA and also meets draft requirements of draft EURO VI test procedures
To compare the mass emission of OBS-ONE with MEXA/CVS on a chassis dyno.
• Euro 6c (draft) regulation specifies the tolerance for PEMS validation.
Table 7: Permissible tolerances Parameter [Unit] Permissible tolerance Distance [km](1) ± 250 m of the laboratory reference THC(2) [mg/km] ± 15 mg/km or 15% of the laboratory reference, whichever is larger CH4
(2) [mg/km] ± 15 mg/km or 15% of the laboratory reference, whichever is larger NMHC(2) [mg/km] ± 20 mg/km or 20% of the laboratory reference, whichever is larger PN(2) [#/km] to be specified CO [mg/km] ± 150 mg/km or 15% of the laboratory reference, whichever is larger CO2
[g/km] ± 10 g/km or 10% of the laboratory reference, whichever is larger NOx
[mg/km] ± 15 mg/km or 15% of the laboratory reference, whichever is larger
Table 7: Permissible tolerances Parameter [Unit] Permissible tolerance Distance [km](1) ± 250 m of the laboratory reference THC(2) [mg/km] ± 15 mg/km or 15% of the laboratory reference, whichever is larger CH4
(2) [mg/km] ± 15 mg/km or 15% of the laboratory reference, whichever is larger NMHC(2) [mg/km] ± 20 mg/km or 20% of the laboratory reference, whichever is larger PN(2) [#/km] to be specified CO [mg/km] ± 150 mg/km or 15% of the laboratory reference, whichever is larger CO2
[g/km] ± 10 g/km or 10% of the laboratory reference, whichever is larger NOx
[mg/km] ± 15 mg/km or 15% of the laboratory reference, whichever is larger Data provided by HORIBA Europe
Table 7: Permissible tolerances Parameter [Unit] Permissible tolerance Distance [km](1) ± 250 m of the laboratory reference THC(2) [mg/km] ± 15 mg/km or 15% of the laboratory reference, whichever is larger CH4
(2) [mg/km] ± 15 mg/km or 15% of the laboratory reference, whichever is larger NMHC(2) [mg/km] ± 20 mg/km or 20% of the laboratory reference, whichever is larger PN(2) [#/km] to be specified CO [mg/km] ± 150 mg/km or 15% of the laboratory reference, whichever is larger CO2
[g/km] ± 10 g/km or 10% of the laboratory reference, whichever is larger NOx
[mg/km] ± 15 mg/km or 15% of the laboratory reference, whichever is larger Data provided by HORIBA Europe
Table 7: Permissible tolerances Parameter [Unit] Permissible tolerance Distance [km](1) ± 250 m of the laboratory reference THC(2) [mg/km] ± 15 mg/km or 15% of the laboratory reference, whichever is larger CH4
(2) [mg/km] ± 15 mg/km or 15% of the laboratory reference, whichever is larger NMHC(2) [mg/km] ± 20 mg/km or 20% of the laboratory reference, whichever is larger PN(2) [#/km] to be specified CO [mg/km] ± 150 mg/km or 15% of the laboratory reference, whichever is larger CO2
[g/km] ± 10 g/km or 10% of the laboratory reference, whichever is larger NOx
[mg/km] ± 15 mg/km or 15% of the laboratory reference, whichever is larger
Reference (Bag) = 148.3 mg/kg
Draft Regulation states tolerance = ±150 mg/km, or 15%, whichever is greater (~300 mg/kg)
Measuring what is considered to be noise of PEMS CO detection, yet still within 6% of reference (Bag)
Recent advancements have allowed for great PEMS Improvements
Ease of PEMS InstallationSmaller sizeInstallation options; modular PEMS, dual exhaust/tube
More reliable and functional PEMS systemsHealth checks and tracking of regulatory checksAutomated regulatory verification/quality checksAdvanced software and post-processing
Better accuracy and correlation to the laboratory referenceDual CLD in PEMS – Lab StandardHot / Wet (NDIR/CLD/FID) No Dry-Wet calculation requiredReal-Time H2O interference compensation