Data Driven Approach To Vehicle Emissions Reduction
2016-12
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Data Driven Approach To Vehicle Emissions Reduction
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2016-12
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Anthropogenic climate change and air pollution resulting from vehicle emissions are major issues facing society. Recent research and government regulations have focused on reducing these emissions through efficiency improvements, advanced aftertreatment technology and ever-tighter regulations. However, despite these advances vehicles still exhibit high emissions during actual use as compared to laboratory or certification testing. Using modern data collection techniques, I identified that electrification and hybridization of transit buses can reduce vehicle power consumption by up to 72% under “real-world” driving conditions, thus decreasing vehicle CO2 emissions. To illustrate the process behind vehicle data collection and offer a use-case for future vehicle connectivity, I discuss the development of a novel mass-based automatic passenger counter to provide a more accurate, lower-cost passenger counting method which can be retrofitted on existing transit buses. Initial results indicate this new passenger counting technology has an accuracy of 97%, however miscounts occur during times when the bus is kneeling, leaving an opportunity for future research. Using measurements from standard exhaust sensors I revealed that NOx emissions of 2013 model year (MY) transit buses were 3-9 times the federal test procedure (FTP) certification limit under “real-world” driving conditions while complying with all regulated standards. To help identify the systematic and physical causes for these high NOx emissions I developed a novel spatial emissions mapping technique called Lagrangian Hotspot Analysis, which used connected vehicle technology to identify spatial influences on vehicle emissions. Results indicate that a hotspot located in the vicinity of a bus stop and intersection had an emissions rate of roughly 3.3 times that of the route average, with these high emissions being attributed to the long idle periods and slow speeds. Instances of cold start and uphill accelerations were also found to increase NOx emissions. Finally, I compared a 2013MY and 2015MY conventional diesel bus to evaluate technology improvements between the generations with the key finding that NOx emissions from the 2015MY bus are reduced by 80% compared to the 2013MY. Further, the NOx emissions were lower than the FTP cycle limit under real-world driving. After the 2013MY bus was updated with the emissions aftertreatment technology of the 2015MY bus, I observed the same NOx reduction in the 2013MY bus. I attribute this reduction to increases in urea consumption through optimization of urea dosing strategy. Such findings imply that certification NOx levels are possible under real-world driving and that upgrading existing buses with modern aftertreatment systems can provide substantial NOx reductions.
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University of Minnesota Ph.D. dissertation. December 2016. Major: Mechanical Engineering. Advisor: William Northrop. 1 computer file (PDF); x, 101 pages.
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Kotz, Andrew. (2016). Data Driven Approach To Vehicle Emissions Reduction. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/190544.
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