Uncertainty in Gravimetric Analysis Required for LEV III Light-Duty
                    Vehicle PM Emission Measurements

Swanson, Jacob; Pham, Liem; Xue, Jian; Durbin, Tom; Russell, Robert L.; Miller, W.J.; Kittelson, David B.; Jung, Heejung; Johnson, Kent C.

doi:10.4271/03-11-03-0024

Cited by 4 publications

(3 citation statements)

References 7 publications

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“…In fact, the emission rates for all but a few of the newer technology vehicles were below 1 mg/bhp-hr, which could be due to some slight modifications to the control strategies for some of the newer vehicles. For all the PM mass emissions presented, the filter weights were below 40 mg at the 2 mg/bhp-hr level and below 20 mg for the 1 mg/bhp-hr emission level, which is near the detection limits of the measurement method (Swanson et al, 2017). Clearly, the DPF provided the needed PM control efficiency for all driving conditions tested in this research.…”

Section: Resultsmentioning

confidence: 64%

Differences between emissions measured in urban driving and certification testing of heavy-duty diesel engines

Dixit¹,

Miller²,

Cocker³

et al. 2017

Atmospheric Environment

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Emissions from eight heavy-duty diesel trucks (HDDTs) equipped with three different exhaust aftertreatment systems (ATS) for controlling nitrogen oxide (NO x) emissions were quantified on a chassis dynamometer using driving schedules representative of stop-and-go and free-flow driving in metropolitan areas. The three control technologies were: 1) cooled exhaust gas recirculation (CEGR) plus a diesel particulate filter (DPF); 2) CEGR and DPF plus advanced engine controls; and 3) CEGR and DPF plus selective catalytic reduction with ammonia (SCR). Results for all control technologies and driving conditions showed PM emission factors were less than the standard, while selected non-regulated emissions (ammonia, carbonyls, and C 4 eC 12 hydrocarbons) and a greenhouse gas (nitrous oxide) were at measurement detection limits. However, NO x emission factors depended on the control technology, engine calibration, and driving mode. For example, emissions from engines with cooled-exhaust gas recirculation (CEGR) were 239% higher for stop-and-go driving as compared with free-flow. For CEGR plus selective catalytic reduction (SCR), the ratio was 450%. A deeper analysis was carried out with the assumption that emissions measured for a drive cycle on either the chassis or in-use driving would be similar. Applying the same NTE rules to the chassis data showed emissions during stop-and-go driving often exceeded the certification standard and >90% of the driving did not fall within the Not-To-Exceed (NTE) control area suggesting the NTE requirements do not provide sufficient emissions control under inuse conditions. On-road measurement of emissions using the same mobile lab while the vehicle followed a free-flow driving schedule verified the chassis results. These results have implications for scientists who build inventories using certification values instead of real world emission values and for metropolitan populations, who are exposed to elevated emissions. The differences in values between real world emissions and certification cycles should be narrowed. For example, one might use a different mix of cold and hot start testing to greater emphasize low temperature/load operation, a separate cycle to specifically characterize low-load operation, or broaden the in-use compliance testing requirements and associated conformity factors to incorporate a wider envelope of vehicle operation, especially at low load conditions. .

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Section: Resultsmentioning

confidence: 64%

Differences between emissions measured in urban driving and certification testing of heavy-duty diesel engines

Dixit¹,

Miller²,

Cocker³

et al. 2017

Atmospheric Environment

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“…It is also worthwhile to evaluate the PM differences in the context of the future 2025 California LEVIII PM emissions standard of 1 mg/mi, as there is considerable interest in how effective gravimetric and other methodologies are in quantifying PM emissions at levels below 1 mg/mi (Xue et al, 2018;Sardar et al, 2015;Swanson et al, 2018). If the comparisons were based on the future 1.0 mg/mi PM standard, the average differences reduce to −2% to +26% for the AVL total PM mass measurements [StdDif_% = (NCEM-[MSS + GFM])/1.0] and to −1% to 43% for the AVL MSS soot measurements.…”

Section: Pm Emissionsmentioning

confidence: 99%

A comparison of a mini-PEMS and a 1065 compliant PEMS for on-road gaseous and particulate emissions from a light duty diesel truck

Yang

Durbin

Jiang

et al. 2018

Science of The Total Environment

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The primary goal of this study was to compare emissions measurements between a 1065 compliant PEMS, and the NTK Compact Emissions Meter (NCEM) capable of measuring NOx, PM, and solid PN. Both units were equipped on a light-duty diesel truck and tested over local, highway, and downtown driving routes. The results indicate that the NOx measurements for the NCEM were within approximately ±10% of those the 1065 compliant PEMS, which suggests that the NCEM could be used as a screening tool for NOx emissions. The NCEM showed larger differences for PM emissions on an absolute level, but this was at PM levels well below the 1 mg/mi level. The NCEM differences ranged from -2% to +26% if the comparisons are based on a percentage of the 1.0 mg/mi standard. Larger differences were also seen for PN emissions, with the NCEM measuring higher PN emissions, which can primarily be attributed to a zero current offset that we observed for the NCEM, which has been subsequently improved in the latest generation of the NCEM system. The comparisons between the 1065 compliant PEMS and the NCEM suggest that there could be applications for the NCEM or other mini-PEMS for applications such as identification of potential issues by regulatory agencies, manufacturer evaluation and validation of emissions under in-use conditions, and potential use in inspection and maintenance (I/M) programs, especially for heavy-duty vehicles.

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“…128 Clean room environments are needed to further reduce variability. 129 A third consideration is the influence of interferences in real matrices which may increase the LOD. 130 Estimates of RCS measurement uncertainty 1.7.2…”

Section: Methods Codementioning

confidence: 99%

Development of spectroscopic techniques for the measurement of Respirable Crystalline Silica

Stacey¹

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Inhalation of aerosols containing respirable-sized crystalline silica (RCS) is a significant hazard for hundreds of thousands of workers in Great Britain (GB), which can cause lung cancer and silicosis. There are elevated levels of disease attributed to exposure to RCS in GB. Personal aerosol monitoring provides an indication of a person’s exposure to RCS, which correlates to the potential risk of ill-health. RCS is often measured in a portion of the aerosol collected in the workplace using X-ray diffraction (XRD) or Fourier Transform Infrared (FTIR) instruments. Uncertainty of XRD or FTIR measurements can exceed international requirements for occupational hygiene analyses at RCS concentrations where there remains a significant risk to worker health. This thesis investigates the application of Raman spectroscopy to improve sensitivity and limits of detection (LOD) for RCS measurements and chemometric methods to improve FTIR measurements when interference is present. For Raman spectroscopy, a feasibility study was undertaken employing optimal measurement conditions and artificial dust mixtures. This study was developed into a method to assess in-respirator samples of RCS from a breathing manikin challenged with a simulated work task. RCS inward leakage ratios (ILRs) based on mass concentration were compared with particle mass and number concentration ILRs from particle counting instruments. The performance of Raman spectroscopy was compared with XRD to assess its limitations when measuring sub-fractions of quartz and RCS in 119 samples from stonemasonry activities. For FTIR, the performance of chemometric methods were compared when measuring artificially prepared mixtures with kaolinite interference and the measurement uncertainty of a Principal Component Regression method was evaluated using real mine dusts. This work was the first to demonstrate the potential of Raman spectroscopy for quantitative measurements of RCS at low concentrations (less than 1μg.m-3). When measuring respirable quartz, Raman response is directly proportional to the mass of analyte when the depth of the sample is a couple of layers. For the quartz standard A9950, this depth is less than 5 μm (which equates to about 3.6 layers of particles 1.39 μm in diameter). An increase in Raman response/μg v was observed at mass loadings above this particle density. The change in the Raman band response is coincident with the depth of sample deposit where significant attenuation of the XRD response would occur due to absorption by multilayers of particles. The Raman band integrated area obtained similar mass values to that measured with XRD integrated intensity when analysing sub-fractions of dusts with differing particle size. Measurements of 119 stone dust samples highlighted the advantage of Raman spectroscopy to quantify quartz with zircon. For FTIR, a multicomponent chemometric analysis of aerosol particulate on filters, was demonstrated, which substantially improves the accuracy of FTIR measurements of quartz in mine dusts. Nevertheless, the measurement of RCS remains potentially challenging due to the range of industries and exposures. This Raman spectroscopy work supported other Health and Safety Executive research to investigate differences between emissions of natural and artificial stones. The short sampling times for laboratory-based experiments would have resulted in many of the samples reporting below or at the LOD of current measurement techniques. Therefore, the use of Raman spectroscopy made the findings of the research more comprehensive.

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Uncertainty in Gravimetric Analysis Required for LEV III Light-Duty Vehicle PM Emission Measurements

Cited by 4 publications

References 7 publications

Differences between emissions measured in urban driving and certification testing of heavy-duty diesel engines

Differences between emissions measured in urban driving and certification testing of heavy-duty diesel engines

A comparison of a mini-PEMS and a 1065 compliant PEMS for on-road gaseous and particulate emissions from a light duty diesel truck

Development of spectroscopic techniques for the measurement of Respirable Crystalline Silica

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