Date of Graduation
Statler College of Engineering and Mineral Resources
Mechanical and Aerospace Engineering
Heavy-duty diesel engines (HDDEs) are currently certified in an engine dynamometer test cell over defined test cycles, such as the Federal Test Procedure (FTP) or the Supplemental Emissions Test (SET). In addition to certification testing, those HDDEs are subjected to in-use testing where gaseous emissions levels are not to exceed 125% of the certification level plus an additional 0.5 g/bhp-hr for instrument and analyzer inaccuracies. These HDDEs are required to meet these limits in the Not-To-Exceed (NTE) zone, which is defined by 40 CFR §86.1370-2007. In this method, emissions are calculated when an engine is operating in the NTE zone for a continuous time period of at least 30 seconds in length.;A work window based method has been developed to calculate in-use emissions for all engine speeds and engine loads. At each data point in an in-use test, engine speed and engine torque are read from the engine's electronic control unit, and along with time, are used to determine instantaneous engine power. Instantaneous work is calculated using this power and the time differential in the data collection. Work is then summed until the desired amount of work is accumulated. The emissions levels are then calculated for that window of work. It was determined that a work window equal to the theoretical FTP cycle work best provides a means of comparison to the FTP certification standard. Also, a failure criterion has been established based on the amount of power in the work window to determine if a particular work window is legitimate.;Data from engines ranging in model year from 1996 to 2003 of 31 different test vehicles were evaluated for over 180 in-use tests. These engines had displacements from approximately 6 L to 12 L with power ratings from roughly 300 hp to 500 hp. The main focus of the study was on brake-specific oxides of nitrogen (NOX) emissions from these engines. For 84% of all tests, the maximum work window bsNOX results were below the maximum bsNOX values calculated using the 30 second window NTE approach. The repeatability of in-use tests based on individual engine, test route, and engine certification family was examined by comparing averages and standard deviations of the results. Technology comparisons showed that for identical displacements and ratings, 2003 engines produced average ranges of 17% to 47% less NOX than 2001 engines. Highway test routes caused engines built prior to 2001 to emit 26% higher bsNOX values than urban test routes. No individual route appeared to cause 2001 and newer engines to emit higher NOX emissions than other routes.;It was concluded that the work window method provides an accurate alternative approach to calculating brake-specific in-use NOX emissions. Results for over 57% of the tests show that average in-use brake-specific NO X emissions were at or below the FTP NOX certification level of these engines. A variation of the work window was also developed based on distance to study inventory emissions for a few select in-use tests.
Shade, Benjamin C., "A work-based window method for calculating in-use brake-specific oxides of nitrogen emissions of heavy -duty diesel engines" (2006). Graduate Theses, Dissertations, and Problem Reports. 3450.