Chassis Dynamometer Evaluation of On-board Exhaust Emission Measurement System Performance in SI Car under Transient Operating Conditions

Ropkins, Karl; Tate, James; Li, Hu; Andrews, Gordon E.; Hawley, Gary; Bell, MC

doi:10.4271/2008-01-1826

Cited by 9 publications

(1 citation statement)

References 12 publications

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“…Such comparisons are rare in the literature, even though the engine cold start topic is widely investigated (see Introduction). One study that compared a heated NDIR with the corrected dry laboratory measurement found 7% for a gasoline vehicle, but it was attributed to the heated NDIR water corrections [37]. Another study that compared the FTIR with the laboratory analyzers showed that the differences of the gasoline vehicles were higher than of the diesel vehicles for CO 2 [26].…”

Section: Discussionmentioning

confidence: 99%

Exhaust Gas Condensation during Engine Cold Start and Application of the Dry-Wet Correction Factor

2019

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Gas components, like carbon monoxide (CO) and dioxide (CO2), can be measured on a wet- or dry-basis depending on whether the water is left or removed from the sample before analysis. The dry concentrations of gaseous components in the exhaust from internal combustion engines are converted to wet concentrations with conversion factors based on the combustion products and the fuel properties. Recent CO2 measurements with portable emissions measurement systems (PEMS) compared to laboratory grade equipment showed differences during the first minutes after engine start. In this study we compared instruments measuring on a dry- and wet-basis using different measuring principles (non-dispersive infrared detection (NDIR) and Fourier-transform infrared spectroscopy (FTIR)) at the exhaust of gasoline, compressed natural gas (CNG), and diesel light-duty and L-category vehicles. The results showed an underestimation of the CO2 and CO mass emissions up to 13% at cold start when the conversion factor is applied and not direct “wet” measurements are taken, raising concerns about reported CO2 and CO cold start emissions in some cases. The underestimation was negligible (<1%) for CO2 when the whole test (20–30 min) was considered, but not for CO (1%–10% underestimation) because the majority of emissions takes place at cold start. Exhaust gas temperature, H2O measurements and different expressions of the dry-wet corrections confirmed that the differences are due to condensation at the exhaust pipes and aftertreatment devices when the surface temperatures are lower than the dew point of the exhaust gases. The results of this study help to interpret differences when comparing instruments with different principles of operation at the same location, instruments sampling at different locations, or the same instrument measuring different driving test cycles or at different ambient temperatures (e.g., −7 °C).

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Section: Discussionmentioning

confidence: 99%

Exhaust Gas Condensation during Engine Cold Start and Application of the Dry-Wet Correction Factor

2019

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Robust surrogate measurement correction using generalised additive model

Ropkins¹,

Li²,

Hawley³

et al. 2009

Chemometrics and Intelligent Laboratory Systems

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The impact of road grade on carbon dioxide (CO2) emission of a passenger vehicle in real-world driving

Wyatt

Tate

2014

Transportation Research Part D: Transport and Environment

115

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16To accurately estimate real-world vehicle emission at 1Hz the road grade for each second of data must 17 be quantified. Failure to incorporate road grade can result in over or underestimation of a vehicle's 18 power output and hence cause inaccuracy in the instantaneous emission estimate. This study proposes 19 a simple LiDAR (Light Detection And Ranging) -GIS (Geographic Information System) road grade 20 estimation methodology, using GIS software to interpolate the elevation for each second of data from 21 a Digital Terrain Map (DTM). On-road carbon dioxide (CO 2 ) emissions from a passenger car were 22 recorded by Portable Emission Measurement System (PEMS) over 48 test laps through an urban-23 traffic network. The test lap was divided into 8 sections for micro-scale analysis. The PHEM 24 instantaneous emission model (Hausberger, 2003) was employed to estimate the total CO 2 emission 25 through each lap and section. The addition of the LiDAR-GIS road grade to the PHEM modelling 26 improved the accuracy of the CO 2 emission predictions. The average PHEM estimate (with road grade) 27 of the PEMS measured section total CO 2 emission (n=288) was 93%, with 90% of the PHEM 28 estimates between 80% and 110% of the PEMS recorded value. The research suggests that 29 instantaneous emission modelling with LiDAR-GIS calculated road grade is a viable method for 30 generating accurate real-world micro-scale CO 2 emission estimates. The sensitivity of the CO 2 31 emission predictions to road grade was also tested by lessening and exaggerating the gradient profiles, 32 and demonstrates that assuming a flat profile could cause considerable error in real-world CO 2 33 emission estimation.

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Chassis Dynamometer Evaluation of On-board Exhaust Emission Measurement System Performance in SI Car under Transient Operating Conditions

Cited by 9 publications

References 12 publications

Exhaust Gas Condensation during Engine Cold Start and Application of the Dry-Wet Correction Factor

Exhaust Gas Condensation during Engine Cold Start and Application of the Dry-Wet Correction Factor

Robust surrogate measurement correction using generalised additive model

The impact of road grade on carbon dioxide (CO2) emission of a passenger vehicle in real-world driving

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