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

Abstract

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.

Keywords

Automobile emissions data analysis air-to-fuel ratio secondary air injection exhaust concentrations after-treatment modelling

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