There is a global effort to expand the use of alternative fuels due to their several benefits such as improving air quality with reducing some criteria emissions, reducing dependency on fossil fuels, and reducing greenhouse gases such as carbon dioxide. This dissertation is focused on investigating the impact of two popular alternative fuels, biodiesel and natural gas (NG), on emissions from heavy-duty engines.

Biodiesel is one of the most popular renewable fuels with diesel applications. Although biodiesel blends are reported to reduce particulate matter, carbon monoxide, and total hydrocarbon emissions; there is uncertainty on their impact on nitrogen oxides (NOx) emissions. This dissertation evaluated the effect of biodiesel feedstock, biodiesel blend level, engine technology, and driving conditions on NOx emissions. The results showed that NOx emissions increase with 20% and higher biodiesel blends. Also, in this study some strategies were proposed and some fuel formulations were found for mitigating NOx emissions increases with biodiesel. The impact of 5% biodiesel on criteria emissions specifically NOx was also fully studied in this thesis. As a part of the results of this study, 5% animal-based biodiesel was certified for use in California based on California Air Resources Board emissions equivalent procedure.

NG is one of the most prominent alternative fuels with larger reserves compared to crude oil. However, the quality of NG depends on both its source and the degree to which it is processed. The current study explored the impact of various NG fuels, ranging from low methane/high energy gases to high methane/low energy gases, on criteria and toxic emissions from NG engines with different combustion and aftertreatment technologies. The results showed stronger fuel effects for the lean-burn technology bus.

Finally, this thesis investigated the impact of changing diesel fuel composition on the criteria emissions from a variety of heavy-duty engine technologies. Emissions from an average diesel fuel used throughout the U.S. were compared with a 10% aromatic, ultra-low sulfur diesel fuel used in California with more stringent air quality regulations. The results showed that the emerging aftertreatment technologies eventually eliminate the benefits of the lower aromatic content/higher cetane number diesel fuels.

Increased activity at ports is an indication of economic development and growth; however, it also puts public health, regional air quality and global climate at risk because the exhaust from the marine diesel engines is not subjected to the stringent regulations as on-road engines. This dissertation characterizes the effectiveness of strategies and technologies to mitigate criteria pollutants and the long-lived greenhouse gas, carbon dioxide (CO2) from marine diesel engines. The dissertation also provides insight into the current state-of-art of gaseous and particulate matter portable emission measurement system (PEMS). Results from a project show how to determine the measurement allowance for PEMS in order to provide accurate measurements for the development of emission inventories and subsequently, air pollution mitigating regulations.

In-use gaseous emissions from the two main engines were measured at sea for the first time in order to evaluate the performance of a Code of Federal Regulations (CFR) compliant PEMS against instruments meeting the simplified measurement method (SMM) complaint with International Maritime Organization (IMO).

For the first time, emissions were measured from a modern container vessel with newest engine technologies. The vessel was operated on marine gas oil, a cleaner fuel, in regulated waters and on heavy fuel oil in unregulated waters. Impact of cleaner fuel and newest technologies on the engine was assessed. A simple equation was developed to estimate time required to completely switch fuels which can be used by vessel owners to comply with regional/international fuel regulations.

Vessel speed reduction (VSR), which is a worldwide acceptable strategy for ocean-going vessels (OGVs), was evaluated. The study showed that putting a speed limit on a container OGVs as they sail near ports and coastlines could cut emissions of air pollutants by up to 70%. This study also found that by reducing the vessel speed by a mere 3-6 knots from cruise speed will result in significant reductions of criteria pollutants and carbon dioxide.

Towards the goal of reducing emissions and dependency on fossil fuels, this dissertation explores benefits of consuming hydrotreated algae biofuel in small marine diesel engines for the first time. Significant particulate matter (PM2.5) and nitrogen oxides (NOx) benefits were reported with slight improve in fuel economy when fuel was switched from ultra low sulfur diesel (ULSD) to 50:50 blend of ULSD and algae fuels.

The dissertation investigates the benefits associated with the hybridization of the tugboat. A conventional tugboat was retrofitted with one auxiliary engine, shaft generators, addition of lithium polymer batteries and an energy management system. Up to 30% reduction in NOx, PM2.5 and CO2 was found. The energy management system in the hybrid tugboat allows the use of the auxiliary engine for propulsion as opposed to the only main engines during transit mode, thus leading to the significant reductions.

Another section of this dissertation provides an evaluation of latest PM-PEMS under different environmental and in-use conditions and features performance, accuracy and precision of PM-PEMS compared to the gravimetric reference method. The research from this study shows current PM-PEMS typically underreport the PM emissions compared to the reference method, with the exception of PEMS with photo-acoustic technology which incorporated a gravimetric filter. All PM-PEMS under evaluation performed poorly when encountered with sulfate laden PM during diesel particulate filter (DPF) regeneration.

Secondary organic aerosol (SOA) is formed via the oxidation of volatile organic compounds emitted to the atmosphere from both biogenic and anthropogenic sources. Due to the complexity of atmospheric composition and range of ambient conditions, aerosol models, which are mostly based off observed yields from controlled laboratory chamber experiments, greatly underestimate global SOA formation. To increase the understanding of the formation and properties of ambient SOA, it is imperative to explore ways to improve the complexity of chamber studies while still maintaining a level of control not found outside of the laboratory.

A surrogate mixture of reactive organic gases (ROG) was developed to mimic atmospheric reactivity in an urban environment such as the Los Angeles basin. The ROG mixture controlled the reactivity of the chamber system such that all gas phase species were not heavily affected by the addition of an aerosol forming precursor. The ROG mixture was modified to represent an urban environment with a strong biogenic influence by the addition of isoprene. It was found that isoprene’s behavior in the mixture yielded high aerosol formation compared to previous NOX photo-oxidation studies. Incremental aerosol formation was then defined in the different ROG systems from two aromatic compounds, a monoterpene, and a polyaromatic hydrocarbon. Slightly higher incremental yields were seen from each compound in the biogenic influenced ROG mixture than in the anthropogenic ROG mixture. Furthermore, it was found that the aerosol physical and chemical properties were dictated by the added precursor and were comparable to properties seen in single precursor experiments.

The effect of ambient temperature (5°C to 40°C) on aerosol formation was also explored for α-pinene ozonolysis, m-xylene/NOX photo-oxidation, cyclohexene ozonolysis, and vehicle exhaust photo-oxidation with hydroxyl radical. In all systems except the complex vehicle exhaust mixture, severe hysteresis effects were seen in aerosol formation, with the cold temperature systems forming up to 5 times more aerosol mass. These findings do not support traditional gas/particle partitioning theory which assumes temperature effects are reversible. Physical and chemical properties of the aerosol tended to remain fairly consistent, despite changes in ambient temperature.

This dissertation introduces and makes use of the Particle-into-Liquid-Sampler coupled to a Time-of-Flight mass spectrometer (PILS-ToF), a new instrumental method used here to provide new chemical characterization information on secondary organic aerosol (SOA). The PILS-ToF instrument improves upon drawbacks found in current state-of-the-art mass spectral chemical characterization methods to include lack of time resolution and ion fragmentation by electron impact ionization in the Aerodyne Aerosol Mass Spectrometer (AMS). The functionality of the PILS-ToF for collection and response to SOA particle formation is validated against a scanning mobility particle sizer (SMPS), a widely accepted and standardized physical chemical characterization instrument, for a well characterized SOA formation experiment, dark ozonolysis of á-pinene. The PILS-ToF is also used to lend insight into oligomer growth during the NO photo-oxidation of isoprene. It is of atmospheric importance to study SOA formation from isoprene as it is globally the most abundant non-methane hydrocarbon in the

ambient. SOA from isoprene is further studied using the PILS-ToF as part of the suite instrumentation at the University of California, Riverside, College of Engineering, Center for Environmental Research and Technology (CE-CERT) atmospheric chamber providing a complete chemical and physical characterization of SOA formed by isoprene with various oxidants under a myriad of oxidant concentration conditions. In addition, the PILS-ToF is used, again in tandem with other chemical and physical characterization methods at CE-CERT, to probe temperature effects on SOA formation from isoprene under many different oxidizing conditions. Finally, the PILS-ToF is used to provide new mechanistic information on SOA formation from trimethylamine and tributylamine, two tertiary amines emitted from anthropogenic and animal husbandry processes. For these two teriary amines the PILS-ToF provides evidence of oligomerization giving a potential explanation to the high SOA yields from these parent compounds.

Secondary organic aerosol (SOA) pollution has negative impacts on human health and well-being. While efforts have been made to characterize the chemical reactions leading to SOA formation, reduced nitrogen compounds remain a poorly studied class of chemicals contributing to air pollution. Sources of reduced nitrogen compounds include agricultural emissions, biomass burning, carbon capture sequestration and selective catalytic reduction control devices, low vapor pressure volatile organic compounds (LVP-VOC) found in many consumer products, and charbroiled meats. Understanding the atmospheric chemical mechanisms of reduced nitrogen compounds is important for comprehensive design of effective air pollution strategies. Therefore, this study seeks to determine the impact of reduced nitrogen compound chemistry on SOA formation. Experiments were conducted at the UCR College of Engineering – Center for Environmental Research and Technology (CE-CERT) Atmospheric Processes Laboratory. This facility houses several well characterized indoor environmental chambers, which allow for the study of atmospheric processes under controlled conditions. Chamber experiments consisted of a reduced nitrogen compound being reacted with atmospheric oxidants including hydroxyl radical (OH) and nitrate radical (NO3). The chemical composition of the gas and aerosol species were determined through mass spectrometry techniques. The physical properties of the aerosol, including density, volatility, and hygroscopicity, as well as particle concentration and size distribution were measured with a variety of house built particle mobility analyzers. A suite of gas analyzers were used to measure Ozone, NOx, and CO concentrations. Experiments with primary, secondary, and tertiary aliphatic amines have provided insights into previously undiscovered reaction mechanisms. Aqueous phase acid catalyzed aldol addition/condensation reactions were observed in secondary amine experiments under humid conditions. Carcinogenic nitramines were observed in secondary amine reactions with nitrate radical. Longer chain secondary amines formed less dense aerosol, suggesting the formation of fractal shaped particles. The discovery of oligomer formation in the reaction of amines with methyl functional groups (dimethylamine, trimethylamine, 2-dimethylaminoethanol) with atmospheric radicals has important implications for SOA formation in areas with high concentrations of amine emissions. Meteorological factors including humidity and temperature played an important role in the reaction chemistry of reduced nitrogen compounds. Humidity provided additional, aqueous phase, reaction pathways. Temperature had an effect on gas to particle partitioning, particularly with the amine salts. The concentration of aerosol formed during radical oxidation of amino alcohols has implications on the use of these compounds in carbon capture sequestration control devices.

This dissertation evaluated emissions from heavy-duty diesel vehicles (HDDVs) and marine engines under a variety of different conditions. This dissertation characterizes the NOx emissions of five 2010 and newer, low-mileage, HDDVs equipped with diesel particulate filters (DPFs) and selective catalytic reduction (SCR) systems were evaluated over test cycles representing urban, highway, and stop-and-go driving on a chassis dynamometer. This information can be used to develop “zero mile” emission rates (ZMRs) for emissions inventory modes.

It is important to investigate and understand the differences between certification and in-use emission rates and to understand the factors contributing to these differences and discrepancies. This dissertation evaluated two 2010-compliant HDDVs using an engine-dynamometer, a chassis-dynamometer, and on-road. The results showed that in-use NOx emissions over urban driving cycles of chassis dynamometer, on-road testing and engine dynamometer tests were above the 0.2 g/bhp-hr certification level for both vehicles, with higher emissions for the on-road and chassis dynamometer testing. The differences between the tailpipe NOx emissions could be attributed to several factors, including differences in SCR inlet temperatures, and engine out NOx emissions. The SCR efficiencies were found to be impacted by the SCR inlet temperature. The SCR efficiencies were as a function of load, especially for the manufacturers B truck. The Not to Exceed (NTE) analysis shows that the NTE method has the limitation that it represents only a small percent of real-world operation.

The implementation of an enhanced heavy-duty (HD) Inspection and Maintenance (I/M) program could be a critical element in ensuring the emissions performance of HDDVs over their full useful life. A prototype HD I/M pilot study was conducted where the emissions of 47 vehicles were measured before and after repair. The vehicles showed good reductions post-repair for NOx for some of the higher emitting vehicles, but not significant PM reductions. Based on a review of the potential methods, a comprehensive HD I/M program was proposed with OBD as the primary methodology, remote sensing for validation testing, and mini-PEMS for dispute resolution.

It is important to understand black carbon (BC) emission factors from ships from human health and environmental perspectives. A study of instruments measuring BC and fuels typically used in marine operation was carried out on a small marine engine with and without a sampling condition (SC) system. Six analytical methods measured the BC emissions in the exhaust of the marine engine operated at two load points while burning three fuels. The results showed that both higher engine loads and higher sulfur fuels contributed to higher BC emission factors with engine load having the biggest impact on BC emissions. There was a spread of about a factor of two in the BC emissions measured by the 6 different methods. The SC system improved the comparability of some BC measurements, but only slightly.

Secondary organic aerosol (SOA) from 17 aromatic hydrocarbons is explored in depth for simulated atmospheric photooxidation conditions. The overall objective of this study is to improve our understanding of the chemical and physical processes leading to SOA formation for aromatic systems and identify the key critical parameters necessary to accurately predict SOA formation.

SOA formation potential under low-NO_X atmospheric conditions is found to decrease as the carbon number of parent aromatic hydrocarbon increases while no aerosol formation trends are observed with carbon number for no-NO_X systems. This trend is attributed to the formation of greater fractions of low vapor pressure ring-retaining products from the lighter aromatic hydrocarbons. SOA chemical composition, measured using the Aerodyne High-resolution Time-of-Flight Mass Spectrometer (HR-ToF-AMS), is evaluated for both low-NO_X and no-NO_X conditions. Generally, aerosol formed in this study is observed to be less oxidized than ambient SOA. It is further observed that aerosol formed from aromatics with less substituents attached to the ring has a lower m/z 43 to m/z 44 ratio and a higher O/C ratio, which indicates that lighter aromatic precursors produced a more oxidized SOA than the heavier aromatic precursors. SOA Volatility further supports the observations that lower vapor pressure and more oxidized products of SOA are produced from lighter compounds. A recently proposed empirical relationship between SOA density and elemental ratio (O/C and H/C) is evaluated against real-time density measurements in an effort to extend the applicability of the empirical relationship to aromatic SOA.

Finally, a gas-phase reaction model (SAPRC11) is used to predict the OH and HO₂ levels present for the different aromatic oxidation systems. Generally, it is observed that aerosol formation decreased with increasing [OH]/[HO₂] ratios for both low NO_X and no-NO_X experiments. This trend is possibly attributed to fragmentation of intermediate compounds to form organics with higher volatility in OH radical abundant environments. It is expected that [OH]/[HO₂] ratio can be utilized to help improve the extrapolation of environmental chamber results to prediction of ambient SOA from aromatic precursors.

This thesis enhances our understanding of secondary organic aerosol (SOA) formation from select anthropogenic sources including polycyclic aromatic hydrocarbons (PAHs), PAHs mixed with m-xylene and an atmospheric surrogate, and unburned whole gasoline vapors. Major SOA chemical characteristics and physical properties were explored along with SOA formation within the UCR CE-CERT environmental chamber.

SOA formation was significant for all three PAHs precursors during photooxidation under high NOx, low NOx and extremely low NOx conditions with 1-methylnaphthalene forming the most SOA followed by 2-methylnaphthalene and naphthalene. SOA yields greater than 1.0 were observed for extremely low NOx (H2O2) conditions. The atmospheric reactivity influenced by H2O2, NOx levels, initial VOCs/NO ratios, and all impacted the SOA formation from the PAH precursors. Fractal SOA particles were observed for 1-methylnaphthalene or 2-methylnaphthalene high NOx photooxidation, indicating that SOA in these experiments were solid particles. SOA growth rates (aerosol mass concentration (ΔM0) versus hydrocarbon reacted (ΔHC)) from different PAHs-m-xylene mixtures are correlated with initial m-xylene/NO, PAHs/NO, [OH]/[HO2] ratio, [NO]/[HO2] ratio and [HO2]/[RO2] ratio. Addition of m-xylene to PAHs experiments suppressed SOA formation from the PAH precursor. The chemical composition characteristics such as f44 versus f43 , H/C ratio, O/C ratio, and the oxidation state of the carbon (OSc) show that PAHs-m-xylene SOA continuously ages and the SOA exhibits characteristics of both individual precursors.

Finally, the SOA formation from photooxidation of whole gasoline vapor under varying NOx conditions was found to range from 1.7% to 5.2%. Further, addition of ethanol suppressed the SOA formation. This work shows that the traditional two-product SOA formation model was unable to explain the total SOA formation from the complex gasoline mixture using the actual formation observed for individual aromatic SOA precursors.

Currently, the shipping industry accounts for 4% of the fuel consumption around the globe. With the growing demand for electrification in land-based transportation and infrastructure, contributions to emissions inventories from large ocean-going vessels (OGVs) will continue to become more significant as they account for a larger portion of global fuel consumption. This body of work is an investigation of the real-world effects of modern emissions standards, and fuel regulations, on large ocean-going vessels (OGVs) used in the commercial maritime industry. It is comprised of sample system design and implementation, various studies on the effects of CARB regulated marine fuel, the difference between the regulated emission standards and the real-world emissions of Tier III OGVs, and the effect of vessel speed reduction (VSR) on Tier III emissions.Emissions sampling systems were designed and deployed to two field campaigns in support of this body of work. The first campaign consisted of in use emissions measurements of a steam turbine driven container ship predating emissions regulations. OGVs typically have an operational lifetime of up to 50 years. Therefore, a continued understanding of changes in emissions profiles for older vessels using new fuels is a critical part of future emissions modeling efforts. The second campaign evaluated the emissions profiles of two new build Tier III vessels, the newest EPA technology class for marine emissions standards. The primary emissions were measured and modal data was analyzed to determine the air quality effects of Tier III emissions control technology on OGV emissions.