Abstract
Heavy-Duty Diesel (HDD) engines sold in the United States (U.S.) are also required to demonstrate compliance with U.S.EPA emissions standards during in-use operation. The current methodology used for analyzing In-use emissions in the U.S. is the Not-To-Exceed (NTE) method, while European regulation employs the Work-Based-Window (WBW) method. The primary objective of this study was to understand the sensitivity of the boundary parameters governing the two methods and identifying an optimized set of boundary parameter thresholds such as to increase the dataavailable for evaluation of in-use bsNOx emissions. The study involves evaluation of in-use data acquired using Portable Emissions Measurement System (PEMS) from 6 trucks certified to U.S.EPA 2007 and 2010 emissions standards. The data-driven study provides a comparison of real-world activity using the two in-use emissions quantification techniques, namely, the NTE and WBW methodology. A design of experiments (DOE) approach was used to select the design space that explored the influence of boundary that govern validity of a test point for compliance assessment. In addition, a 3-way ANOVA analysis was used to quantify the effect contribution of the boundary parameters governing the two methods. The analysis provides an in-sight into the differences in magnitude of data utilized for in-use compliance assessment. 3-way ANOVA analysis of the parametric study shows that engine power and tail-pipe exhaust gas temperature thresholds have the strongest effect on the amount of data that qualifies for inuse emissions assessment. The results of the study illustrate the need for changes in boundary conditions for both NTE and WBW methodology to improve the data available for in-use compliance assessment with the inclusion of a wider range of operating conditions and adapt to current and future engine technologies.