Influence of Time-Alignment on the Calculation of Mass Emissions on a Chassis Rolls Dynamometer

Hawley, J G; Brace, Chris; Cox, A.; Ketcher, D. A.; Stark, R

doi:10.4271/2003-01-0395

Cited by 20 publications

(13 citation statements)

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“…In order to compensate for the delay, the emissions data should be shifted back in time to align with the engine operating variables such as power and speed. The importance of time alignment was addressed in detail by Hawley et al [5]. There are several ways in which the emissions data can be time aligned.…”

Section: Time Delay and Compensation For The Time Delaymentioning

confidence: 99%

“…However, any real analyser system will report a distorted signal during the process of measurement. For example, the emissions reported by the analyser may be delayed and dispersed relative to the instantaneous emissions [1][2][3][4][5]. Knowledge of the instantaneous emissions may play an important role in developing both inventory models and superior engine control strategies, and the prediction of instantaneous emissions from measured emissions.…”

Section: Introductionmentioning

confidence: 99%

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Attempts to enhance the differential coefficients method for reconstruction of transient emissions from heavy-duty vehicles

Madireddy

Clark

2008

International Journal of Engine Research

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Engine tailpipe emissions as measured by a sampling system and analyser do not clearly reflect the actual transient emissions from the engine at the tailpipe of the vehicle exhaust. With increasing demand for accurate emissions measurements, several research efforts are being made to compensate for the measurement distortions of the analyser system. The differential coefficients method is one such approach which reconstructs the input signal by approximating the analyser input as a linear combination of the output and the first two derivatives of the output. While the results with this approach were found to be acceptable, this paper focuses on the possibilities of improving the accuracy of the reconstruction by altering the ways in which the numerical derivatives are computed and by considering higher order derivatives in the linear combination. It was found that the use of backward differences in computing the numerical derivatives proved more effective than forward differences. Using higher order derivatives has shown improvement of about 10 per cent over using just the first two derivatives, but this margin may be important for model accuracy or for assessing pass/fail emissions criteria.

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Section: Time Delay and Compensation For The Time Delaymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Attempts to enhance the differential coefficients method for reconstruction of transient emissions from heavy-duty vehicles

Madireddy

Clark

2008

International Journal of Engine Research

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“…Kamarianakis and Gao 4 proposed a statistical modelling framework to account for the dynamics of these variable transport delays. Hawley et al 5 highlighted the sensitivity of conversion efficiency calculation to the time alignment between the vehicle speed trace and instantaneous emission measurements. Krishnamurthy and Gautam 6 presented a preliminary development of a quality assurance methodology for emission measurements.…”

Section: Introductionmentioning

confidence: 99%

Post-processing of vehicle emission test data for use in exhaust after-treatment modelling and analysis

Sharma

Ramanathan

2012

Proceedings of the Institution of Mechanical Engineers, Part D:

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The accurate measurement of transient engine-out exhaust compositions, flow rate and temperature is critical for analysing and understanding the performance of exhaust system after-treatment components. This paper describes procedures for processing the transient emission data measured at vehicle test sites. These procedures include estimation of the hydrogen, oxygen and water concentrations and correction of the engine-out exhaust gas flow for the first few seconds of the drive cycle for non-oxygenated and oxygenated fuels. Both secondary air injection and non-secondary air injection applications are discussed. A procedure for accurately measuring the exhaust gas temperature during transient operations is also described with a specific thermocouple recommended for best results. A checklist for handling and processing the measured data is also provided. In addition to providing better data for further analysis and understanding of exhaust after-treatment components, the procedures listed in this work allow consistent and reliable input data to be generated for the mathematical model and model-based application studies using the measured vehicle emission data.

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Section: Problemas Asociados a La Medición Dinámica De Emisionesunclassified

“…Adicionalmente se tenía la necesidad de relacionar las emisiones instantáneas con la condición de operación del vehículo en los diferentes puntos de los ciclos de prueba normalizados. Messer y Clark de la Universidad de West Virginia (Messer et al, 1995 y Clark & Ganesan, 2001, Weilenmann y Ajtay del Laboratorio Federal Suizo (Weilenmann et al, 2001;, Ajtay & Weilenmann, 2004 y Ajtay et al, 2005 y Bannister y Hawley , Bannister et al, 2007, Hawley et al, 2003 y Hawley et al, 2004 de la Universidad inglesa de Bath estudiaron este problema para los equipos de medida de emisiones usados en banco de rodillos.Martin Weilenmann define muy bien el problema de la medición dinámica instantánea, dice que a pesar de que los analizadores permitan frecuencias de muestreo de 1 Hz, las mediciones realizadas no reflejan la realidad, pues el tiempo de respuesta de los analizadores y la fluidodinámica de los gases de escape distorsionan las señales medidas haciéndose necesario su reconstrucción (Weilenmann et. Al, 2003).…”

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Aspectos de la medición dinámica instantánea de emisiones de motores. Aplicación al desarrollo de un equipo portátil y una metodología para estudios de contaminación de vehículos en tráfico real.

González¹

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Influence of Time-Alignment on the Calculation of Mass Emissions on a Chassis Rolls Dynamometer

Cited by 20 publications

References 1 publication

Attempts to enhance the differential coefficients method for reconstruction of transient emissions from heavy-duty vehicles

Attempts to enhance the differential coefficients method for reconstruction of transient emissions from heavy-duty vehicles

Post-processing of vehicle emission test data for use in exhaust after-treatment modelling and analysis

Aspectos de la medición dinámica instantánea de emisiones de motores. Aplicación al desarrollo de un equipo portátil y una metodología para estudios de contaminación de vehículos en tráfico real.

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