Uncertainties in Measurements of Emissions in Chassis Dynamometer Tests

Mohanta, Lokanath; Iyer, Suresh; Mishra, Partha; Klinikowski, David

doi:10.4271/2014-01-1584

Cited by 11 publications

(3 citation statements)

References 10 publications

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“…This calculation needs correct time alignment of the particles signal with the exhaust flow rate. Misalignment of ±1 second in our measurements resulted in differences of ±5% (up to ±10% in some cases), in agreement with others [28]. For all calculations the mean PCRF (particle number concentration reduction factor) as defined in current regulations was used (i.e., average of 30 nm, 50 nm, and 100 nm).…”

Section: Methodssupporting

confidence: 89%

Particle Number Measurements Directly from the Tailpipe for Type Approval of Heavy-Duty Engines

et al. 2019

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The type approval of heavy-duty engines requires measurement of particulates downstream of a proportional to the exhaust flow partial flow dilution system. However, for particle number systems, which measure in real time, this is not necessary and a fixed dilution could be used. In order to assess this dilution possibility, an inter-laboratory exercise was conducted, where a “Golden” system measuring directly from the tailpipe with “hot” (150 °C) fixed dilution was compared with the laboratory regulated systems. Additional “Golden” counters were measuring from 10 nm, below the current cut-off size of 23 nm defined in the regulation, in order to collect data below 23 nm and to confirm that the direct sampling is also possible for smaller sizes. Seven diesel engines and two CNG (compressed naturals gas) engines were used in six laboratories. The results of the “Golden” instruments were within 25% in most cases, reaching 40% in two laboratories for both >23 nm and >10 nm. The repeatability of the measurements (10% to 40%) remained the same for both systems with both cut-off sizes. One test with regeneration showed clear difference between the 10 nm systems, indicating that the thermal pre-treatment only with evaporation tube might not be adequate. Another system measuring from the tailpipe with a fixed “cold” (at ambient temperature) dilution gave differences of up to 50% in most cases (on average +26%). Dedicated tests with this system showed that the differences were the same with fixed or proportional dilution, indicating that it is not the concept that resulted in the overestimation, but the calibration of the system. The main conclusion of this study is that direct sampling with fixed dilution from the tailpipe can be introduced in the future regulation.

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Section: Methodssupporting

confidence: 89%

Particle Number Measurements Directly from the Tailpipe for Type Approval of Heavy-Duty Engines

et al. 2019

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“…The results of the SPN emissions at the tailpipe need correct time alignment between the SPN signal and the exhaust flow rate. Misalignment of a few seconds can have a significant effect [35]. Here, the effect of misalignment was checked by moving the SPN signal for ±1 second.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Identification and Quantification of Uncertainty Components in Gaseous and Particle Emission Measurements of a Moped

et al. 2019

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The recent Euro 4 and 5 environmental steps for L-category vehicles (e.g., mopeds, motorcycles) were mainly designed to reduce the emissions of particulate matter and ozone precursors, such as nitrogen oxides and hydrocarbons. However, the corresponding engine, combustion, and aftertreatment improvements will not necessarily reduce the solid particle number (SPN) emissions, suggesting that a SPN regulation may be necessary in the future. At the same time, there are concerns whether the current SPN regulations of passenger cars can be transferred to L-category vehicles. In this study we quantified the errors and uncertainties in emission measurements, focusing on SPN. We summarized the sources of uncertainty related to emission measurements and experimentally quantified the contribution of each uncertainty component to the final results. For this reason, gas analyzers and SPN instruments with lower cut-off sizes of 4 nm, 10 nm, and 23 nm were sampling both from the tailpipe, and from the dilution tunnel having the transfer tube in closed or open configuration (i.e., open at the tailpipe side). The results showed that extracting from the tailpipe 23–28% of the mean total exhaust flow (bleed off) resulted in a 24–31% (for CO2) and 19–73% (for SPN) underestimation of the emissions measured at the dilution tunnel. Erroneous determination of the exhaust flow rate, especially at cold start, resulted in 2% (for CO2) and 69–149% (for SPN) underestimation of the tailpipe emissions. Additionally, for SPN, particle losses in the transfer tube with the closed configuration decreased the SPN concentrations around 30%, mainly due to agglomeration at cold start. The main conclusion of this study is that the open configuration (or mixing tee) without any instruments measuring from the tailpipe is associated with better accuracy for mopeds, especially related to SPN measurements. In addition, we demonstrated that for this moped the particle emissions below 23 nm, the lower size currently prescribed in the passenger cars regulation, were as high as those above 23 nm; thus, a lower cut-off size is more appropriate.

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“…A procedure is described in [5] to determine the experimental uncertainties in the measurement of tailpipe emissions of carbon dioxide, carbon monoxide, nitrogen oxides, and hydrocarbons during tests performed for various chassis dynamometer driving cycles. Although information is readily available on how a vehicle model's emission system performs under certification conditions, it is not widely known how it performs after years of use [6].…”

Section: Introductionmentioning

confidence: 99%

Air-fuel ratio regulation using a discrete-time internal model controller

Kahveci

Impram

Genç

2014

17th International IEEE Conference on Intelligent Transportation Systems (ITSC)

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As the transportation systems become increasingly complex and crowded, more strict standards are proposed to reduce the levels of emissions produced by motor vehicles and hence the negative effects these emissions have on public health and the environment. The efficiency of three-way catalysts typically employed in Spark Ignition (SI) engines depends primarily on the Air-Fuel Ratio (AFR) regulation performance. We implement an Internal Model Controller (IMC) combined with an adaptive law in discrete-time and use this structure to address the AFR control problem despite the presence of parametric uncertainties.

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Uncertainties in Measurements of Emissions in Chassis Dynamometer Tests

Cited by 11 publications

References 10 publications

Particle Number Measurements Directly from the Tailpipe for Type Approval of Heavy-Duty Engines

Particle Number Measurements Directly from the Tailpipe for Type Approval of Heavy-Duty Engines

Identification and Quantification of Uncertainty Components in Gaseous and Particle Emission Measurements of a Moped

Air-fuel ratio regulation using a discrete-time internal model controller

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