Berk Demirgok

Date of Graduation

2018

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Arvind Thiruvengadam

Committee Co-Chair

V'yacheslav Akkerman

Committee Member

Marc Cyrill Besch

Committee Member

Ross Ryskamp

Committee Member

Bharadwaj Sathiamoorthy

Abstract

Measurement of in-use emissions from heavy-duty (HD) vehicles under real-world operation has been widely performed by using portable emissions measurement system (PEMS). PEMS serve as an accurate and lightweight emissions measurement system to evaluate in-use emissions from HD vehicles. However, emissions measurement using PEMS instrumentation can be time consuming and labor intensive. Advantage of utilizing already existing on-board sensors such that they can potentially provide an alternative measurement methodology to the PEMS. A successful implementation of an on-board NOx sensor-based methodology for assessing in-use NOx emissions will allow for a cost-effective and simplified approach to monitor real-world, NOx emission rates. The technology of on-board NOx sensors is in its initial stages to be used to monitor in-use NOx emissions and the ability of the sensor to measure NO x concentration during selective catalytic reduction (SCR) activity period is of concern. Furthermore, the on-board NOx sensors are also subject to various cross-sensitivity and durability concerns.;The primary objective of this dissertation is to compare the on-board NOx sensor response and accuracy against laboratory grade instrumentation that include PEMS using Non-Dispersive Ultra-Violent (NDUV) and Fourier transform infrared spectroscopy (FTIR) measurement to assess the measurement thresholds of on-board NOx sensors. The study compares the cross-sensitivity of the NOx sensors to ammonia (NH3) concentration in the exhaust. NH3 slip from SCR is believed to interfere with NO x measurements using Zirconium oxide sensors and this study will discuss NH3-NOx cross sensitivity on on-board NO x sensors during real-world HD vehicle activity. Results from this study will compare on-board NOx sensor measurement capabilities and they will be assessed at different power levels related to different SCR conversion efficiency and different NOx concentration levels related to measurements obtained from a laboratory grade emissions measurement system FTIR. The secondary objective of this work is to explore and modify boundary conditions for the Not-to-exceed (NTE) and (Work-based window) WBW regulatory protocols due to deficiencies of current protocols in appropriately characterizing regulated emissions especially during the port drayage and urban activity, characterized by low-load engine operation. Thus, new revised regulatory protocols for a wide range of driving activity are needed for an accurate characterization of in-use NOx emissions.

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