Browsing by Subject "Emissions"
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Item All Wood Products Neighborhood Dispute Report(2004) Cornwall, FaithItem Data Driven Approach To Vehicle Emissions Reduction(2016-12) Kotz, AndrewAnthropogenic 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.Item Effects of homogeneous charge compression ignition (HCCI) control strategies on particulate emissions of ethanol fuel.(2010-12) Franklin, LukeThis thesis presents a systematic investigation into the formation of particulate matter in homogeneous charge compression ignition (HCCI) engines. These engines are representative of the emerging generation of low sooting engine technology. Early research in the field concluded that engines operating with this combustion strategy could offer Diesel like efficiency while simultaneously reducing emissions of particulate matter and the oxides of nitrogen to nearly negligible levels. While quantification of gas phase emissions has changed little through modern regulatory history, the metrics defining particulate emissions and the state of understanding of the research community are rapidly evolving. Advances in technology for characterizing particulate emissions from spark ignition and compression ignition engines have been applied to HCCI emissions and the results indicate the production of significant quantities, by both number and mass, of particles from the HCCI combustion strategy. A relationship has been identified between in-cylinder behavior, and both gaseous and particulate emissions. It has been shown to be valid for 2 different fuels and multiple engine loads. Characteristics of the particulate matter suggest it is formed via gas to particle conversion, or nucleation, of the lighter distillates from the engines lubricating oil.Item Efficacy Of Heated Hydrous Ethanol Injection For Improving Emissions From Dual Fuel Diesel Engines(2017-05) Nord, AlexWith emissions standards becoming ever more stringent, aftermarket dual-fuel solutions are being developed to allow legacy diesel engines to reach higher regulatory emissions tiers. Manufacturers are reluctant to adopt dual-fuel systems due to perceived lack of consumer interest. However, the use of aftermarket dual-fuel systems with partially renewable fuels has sparked interest in limited markets. Previous research has shown slight emissions reduction benefits from fumigation with 120 proof hydrous ethanol in a diesel engine using a commercially available dual-fuel system. However, the findings do not match manufacturer claims of emissions reductions. The work presented here examines the design, development, performance, and emissions from an engine equipped with a novel aftermarket port fuel injection (PFI) dual fuel system with a fuel heating system integrated into the fuel injector rail. Finite element modeling techniques in ANSYS were used to optimize the heat exchanger and analyze its performance. In addition, cross-sections and flow path lines were created in ANSYS to examine thermal profiles and flow turbulence at varying ethanol flow rates. A John Deere 4045HF475 Tier 2 diesel engine was retrofitted with a custom PFI rail designed to inject hydrous ethanol with the ability to preheat the ethanol using circulated hot engine coolant to improve the vaporization and mixing of the secondary fuel and air in the intake port. Port-injected fuel flow was controlled by varying injector pulse width and throttle position was adjusted manually to maintain testing mode parameters. Heated ethanol, unheated ethanol, and diesel only operating modes were run over a modified ISO 8178 eight-point test plan. Fumigant energy fraction (FEF), defined as the amount of energy provided by the fumigant based on the lower heating value (LHV) divided by the total fuel energy, up to 37% was achieved in the experiments. Ethanol fuel rail heat exchanger effectiveness decreased with increasing FEF and log-mean temperature difference (LMTD) increased. These opposite effects were likely due to dimensional design constraints of the heat exchanger limiting the heat transfer. Experiments found that with increasing FEF, engine NO emissions decreased, whereas NO2, CO, THC, and ethanol emissions increased. NO emissions reductions were countered by increasing NO2, resulting in constant NOX emissions. Soot concentrations produced varying trends, but with a tendency to decrease overall at high FEF. Preheating the ethanol with circulated engine coolant yielded few benefits to engine out-emissions. This study showed that the dual-fuel heated PFI rail system provided modest emissions benefits over diesel-only operation. Preheating the liquid ethanol was not as successful as anticipated because ethanol’s high latent heat of vaporization dominated over the sensible heat required to heat the liquid prior to the injectors.Item Energy feedback at the city-wide scale(2014-05) Carter, Richard AllanClimate change is a growing concern throughout the world. In the United States, leadership has so far failed to establish targeted reductions and agreement on mitigation strategies. Despite this, many large cities are taking on the challenge of measuring their emissions, establishing targeted reductions, and defining strategies for mitigation in the form of Climate Action Plans. Reporting of greenhouse gas (GHG) emissions by these cities is usually based on a one-time, annual calculation. Many studies have been conducted on the impact of providing energy use data or feedback to households, and in some cases, institutional or commercial businesses. In most of those studies, the act of providing feedback has resulted in a reduction of energy use, ranging from 2% to 15%, depending upon the features of the feedback. Many of these studies included only electric use. Studies where all energy use was reported are more accurate representations of GHG emissions. GHG emissions and energy use are not the same, depending on the fuel source and in the case of this paper, the focus is on reducing energy use.This research documents the characteristics of the feedback provided in those studies in order to determine which are most effective and should be considered for application to the community-wide scale. Eleven studies, including five primary and six secondary research papers, were reviewed and analyzed for the features of the feedback. Trends were established and evaluated with respect to their effectiveness and potential for use at the community-wide scale.This paper concludes that additional research is required to determine if the use of energy feedback at the city scale could result in savings similar to those observed at the household scale. This additional research could take advantage of the features assessed here in order to be more effective and to implement the features that are best able to scale up. Further research is needed to determine whether combining city-wide feedback with feedback for individual energy users within the city, both residential and commercial, has an even greater impact on reducing energy use and lowering GHG emissions.Item Freight and Logistics E-News March 2014 (Vol. 12, No. 1)(Center for Transportation Studies, 2014-03) Center for Transportation StudiesArticles in this issue: Capacity issues challenge the freight industry; Automated system helps truckers find safe places to park; Pilot study seeks manufacturers’ perspectives on transportation system; New U of M program to explore transportation policy and economic competitiveness; New pilot program to help suppliers reduce greenhouse gas emissions; MAFC annual meeting, Apr. 22–25; FHWA ‘Talking Freight’ seminars; More news and informationItem The Greenest Path: Comparing the Effects of Internal and External Costs of Motor Vehicle Pollution on Route Choice and Accessibility(2016-08-01) Cui, Mengying; Levinson, David MOn-road emissions are a dominant source of urban air pollution, which damages human health. The "greenest path" is proposed as an alternative pattern of traffic route assignment to minimize the costs of emissions or exposure, pursues an environmentally optimal. The framework of a link-based emission cost analysis is built for both internal and external environmental costs and applied to the road network of the Twin Cities Metropolitan area based on the EPA MOVES model. The greenest (internal/external) path is skimmed for all OD pairs to compare the work trip flows on the roads and accessibility distribution. It is shown that the emission cost that travelers impose on others is greater than which they bear. Considering only external emissions costs thus produces a lower accessibility than considering only internal emissions costs. This research contributes to understanding the full cost of travel.Item Impact of Pandemic on Atmospheric Carbon(2021-08) Mosesov, EleonoraThe COVID-19 pandemic has caused a decrease in carbon dioxide emissions. Here we will look at the atmospheric carbon dioxide, carbon-13, and carbon dioxide emissions data in order to determine whether the drop in emissions had an effecton atmospheric carbon dioxide and carbon-13. For carbon dioxide and carbon-13, we look at the trend and the seasonal pattern. To find whether 2020 is an outlier, we find the average values and compare them to previous years, as well as compare the monthly data. The data in 2020 for the atmospheric carbon dioxide and carbon-13 did not show a drop, and was not an outlier.Item Non-linear influences of the built environment on transportation emissions: Focusing on densities(Journal of Transport and Land Use, 2017) Hong, JinhyunCompact development is often recommended to reduce auto-dependency thereby decreasing related energy consumptions and transportation emissions. However, there could be a non-linear relationship between density and transportation emissions because of a possible non-linear association between density and vehicle miles travelled (VMT); low travel speed due to congestion; and the relationship between neighborhood characteristics and vehicle characteristics (e.g., vehicle type and age). In addition, the self-selection issue can exist in the land use-transportation emissions analysis because transportation emissions are often estimated based on travel behavior. Using the 2006 Puget Sound Regional Council (PSRC) Household Activity survey, the follow-up stated preference survey, the Motor Vehicle Emission Simulator (MOVES) data, and the GIS network data, this study investigates the non-linear effects of densities on CO2 equivalent (CO2e) emissions with the consideration of self-selection. Specifically, quadratic forms of population and employment densities, different population density group indicators, and attitudinal factors are employed in the regression models. The results indicate that people living in denser neighborhoods tend to generate fewer CO2e emissions. However, this effect becomes insignificant as population density reaches a certain level.Item Optimal Bus Scheduling Considering Operating Costs and Emissions: A Multiple Objective, Mixed Integer Programming Framework(2015-12) Sun, BixuanTraditional vehicle scheduling problems primarily focus on minimizing operating costs, and few of them consider the environmental impacts of the fleet operation. This study develops a framework that optimizes bus assignments to routes with the objective of minimizing both operating costs and the environmental impacts of emissions. The optimization model is applied in a case study of Metro Transit in Minneapolis/St Paul area. The results show a set of tradeoff relationships between operating costs and emissions. The optimized vehicle assignments generated by the model can significantly reduce both the operating costs and emissions of the current fleet. It is also found that hybrid electric buses were underused by Metro Transit in 2013 and should be assigned to service more often. The analysis can also provide useful supporting information for strategic decisions such as vehicle replacement and purchase.Item Population exposure to ultrafine particles: size-resolved and real-time models for highways(2016-09-14) Zhu, Shanjiang; Marshall, Julian D; Levinson, David MPrior research on ultrafine particles (UFP) emphasizes that concentrations are especially high on-highway, and that time on highways contribute disproportionately to total daily exposures. This study estimates individual and population exposure to ultra-fine particles in the Minneapolis – St. Paul (Twin Cities) metropolitan area, Minnesota. Our approach combines a real-time model of on-highway size-resolved UFP concentrations (32 bins, 5.5 to 600 nm); individual travel patterns, derived from GPS travel trajectories collected in 144 individual vehicles (123 hours at locations with UFP estimates among 624 vehicle-hours of travel); and, loop-detector data, indicating real- time traffic conditions throughout the study area. The results provide size-resolved spatial and temporal patterns of exposure to UFP among freeway users. On-highway exposures demonstrate significant variability among users, with highest concentrations during commuting peaks and near highway interchanges. Findings from this paper could inform future epidemiological studies in on- road exposure to UFP by linking personal exposures to traffic conditions.Item Remote sensing of particulate emissions from heavy-duty vehicles: final report on phase I(1994-09) Chen, Guoguang; Prochnau, Timothy J.This report summarizes the results of initial tests of a remote sensing system capable of real-time detection of particulate emissions from heavy-duty transit vehicles under actual on-road operating conditions. The technique employs optical extinction (sometimes called opacity) to measure concentrations of CO2 and soot in the exhaust plumes from individual vehicles. Two wavelength regions (bands) are used, one of which is sensitive to soot and the other of which is used to monitor CO, levels. From these two measurements, an emissions index can be computed which normalizes the mass of soot emitted by the amount of fuel burned. The primary goal of phase I was ascertain whether the new technique held promise of sufficient sensitivity and accuracy for on-road deployment.Item Solar Thermal Research Project(2005) Bouman, JoeItem Tank to Wheel Emissions of Ethanol and Biodiesel Powered Vehicles as Compared to Petroleum Alternatives: White Paper(Center for Transportation Studies, University of Minnesota, 2010-06) Tessum, Christopher; Marshall, Julian D.; Hill, JasonAir quality modeling of the air pollution effects of alternative fuels must be supported with data on the tailpipe emissions of those fuels relative to conventional fuels. Here a literature review is presented of the tailpipe and evaporative emissions from 85% ethanol (E85), 10% ethanol (E10), and 20% biodiesel (BD20) compared to conventional fuels. It is found that E85 causes both positive and negative changes in emissions relative to gasoline, depending on the pollutant, and the changes in some pollutants have an uncertain sign. E10 and BD20 in general exhibit smaller changes in emissions compared to E85, the impacts of which cannot be fully known without air quality modeling.