Thomas D. Durbin

• PhD
• Engineer at University of California, Riverside

The objective of this research was to collect real-world activity data from agricultural equipment that could be considered when informing air quality and incentive programs in California. This included monitoring 208 tractors via either engine hour records or data loggers, with 103 of these tractors monitored with data loggers. The results showed...

div class="section abstract"> Marine ports are an important source of emissions in many urban areas, and many ports are implementing plans to reduce emissions and greenhouse gases using zero-emission cargo handling equipment. This paper evaluates the performance and activity profiles for various zero-emission (ZE) cargo transport equipment being de...

We used a heavy-duty chassis dynamometer to measure gaseous and particulate emissions from natural gas and diesel-powered yard tractors tested on different driving cycles, some being representative of typical yard tractor operation. The natural gas yard tractors were operated with fuel blends of varying compositions, including a renewable natural g...

This study assessed the real-world emissions from two heavy-duty natural gas vehicles certified to the optional 0.02 g/bhp-hr nitrogen oxides (NOx) standard and one diesel vehicle equipped with diesel particulate filter (DPF) to control particulate matter (PM) mass emissions and selective catalytic reduction (SCR) to control NOx emissions. Testing...

The Onboard Sensing Analysis and Reporting (OSAR) system was developed for continuous monitoring of diesel and natural gas technologies on an annual basis. The scope of the study is to develop a supplementary methodology for in-use emission sensing for compliance, legislative, and automotive industry needs. OSAR started out as a consortium-led rese...

This study assessed the potential of increasing ethanol content in California reformulated gasoline (CaRFG) by investigating the exhaust emissions from a fleet of 20 light-duty vehicles. A baseline CaRFG E10 (10% ethanol by volume) fuel was splash blended with denatured ethanol to create a E15 fuel. Each vehicle/fuel combination were exercised over...

Scope of the study is to investigate real-world exhaust gas emissions generated from Heavy-duty Diesel (HDDEs) and Natural gas (HDNGs) engines. The main focus was on sub-23nm solid (SPN) and total (TPN) particle emissions while the nature of these particles was further investigated with chemical and toxics analysis. Two HDNGs and one HDDE were util...

T his study assessed the on-road gaseous and particulate emissions from a gasoline direct injection (GDI) hybrid electric vehicle (HEV) using portable emissions measurement systems (PEMS). Testing was conducted, while the vehicle was exercised over three routes with different topological and environmental characteristics, representing urban, highwa...

Heavy-duty diesel vehicles (HDDVs) are important sources of urban nitrogen oxides (NOx) in an actual application for environmental compliance. The remote on-board sensing (OBS) is a cost-effective emission reduction approach for HDDVs. NOx emissions from fifty-four sediment hauling trucks were evaluated in a construction area, and this information...

In this study, the regulated emissions, gaseous toxics, and the physical, chemical, and toxicological properties of particulate matter (PM) emissions from a legacy off-road diesel engine operated on hydrogenated vegetable oil (HVO) and HVO blends with biodiesel were investigated. This is one of the very few studies currently available examining the...

Heavy-duty diesel vehicles (HDDVs) are important sources of urban nitrogen oxides (NOx) in an actual application for environmental compliance. The remote on-board sensing (OBS) is a cost-effective emission reduction approach for HDDVs. NOx emissions from fifty-four sediment hauling trucks were evaluated in a construction area and this information w...

Aftertreatment technologies in Tier 4 off-road engines have resulted in significant emission reductions compared to older tier engines without aftertreatments. The appropriate characterization of Tier 4 engine emissions in consideration of aftertreatment operation is important for projecting emissions and developing mitigation strategies. The curre...

Off-road engines represent one of the largest categories for mobile source emissions in the United States. Emissions standards for small off-road diesel engines (SORDEs), which have not been updated since 2004, can be met without the use of aftertreatment on engines below 75 horsepower (hp) for nitrogen oxides (NOx) or below 25 hp for particulate m...

div class="section abstract"> Goods movement and port related activities are a significant source of emissions in many large urban areas. Electrification of diesel cargo handling equipment is one method of reducing community exposure to these emissions, that also provides the potential for reducing greenhouse gas emissions. This study evaluated the...

As the push to reduce air pollutants and carbon dioxide for global warming continues, there is increasing interest in the development and deployment of battery electric vehicles for heavy-duty applications as one of the critical and challenging steps of a broader effort to fully electrify the transportation sector. This study evaluated and quantifi...

This manuscript contains an assessment of tailpipe emissions and secondary aerosol formation from two in-use heavy-duty diesel vehicles (HDDVs) with different aftertreatment systems when operated with ultra-low sulfur diesel (ULSD) and hydrogenated vegetable oil (HVO) operated on a chassis dynamometer. Secondary aerosol formation was characterized...

For the first time, nitrogen oxide (NOx) emissions were systematically investigated during different operating conditions from a single test article on a chassis dynamometer, under real-world (on-road) conditions, on an engine dynamometer after the engine was pulled out of the vehicle, and again on a chassis dynamometer when the engine was installe...

This study assessed the real-world gaseous and particulate emissions for a wet scrubber retrofit to an existing container ocean-going vessel as it cruised from Tacoma Washington to Anchorage Alaska. The vessel was operated with a high sulfur heavy fuel oil and testing was performed following the ISI 8178 E2 steady test cycle. The scrubber unit prov...

Yard tractors (YTs) are trucks used for moving trailers and containers short distances around freight terminals and port facilities, and their diesel engines contribute significantly to nitric oxide (NOx) and particulate matter (PM) emissions to a port’s inventory for the cargo handling equipment (CHE) category. Over time, tougher regulations have...

Add-on aerodynamic devices (cab-roof fairings, side extenders, side skirts, boat-tails and others) for heavy-duty trailers and tractors provide the potential of fuel savings, cost savings, and the reduction of greenhouse gas (GHG) emissions. The goal of this work was to evaluate potential for aerodynamic devices to provide GHG emission reductions f...

A comprehensive study on the effects of photochemical aging on exhaust emissions from a vehicle equipped with a gasoline direct injection engine when operated over seven different driving cycles was assessed using an oxidation flow reactor. Both primary emissions and secondary aerosol production were measured over the Federal Test Procedure (FTP),...

This study assessed the real-world nitrogen oxide (NOx) emissions from 50 heavy-duty vehicles of different vocations and engine technologies using portable emissions measurement systems (PEMS). This is one of the most comprehensive in-use emissions studies conducted to date, which played a key role in the development of CARB’s (California Air Recou...

This study assessed the gaseous and particulate emissions from a Tier 2 oceangoing vessel using two emission control area (ECA) compliant fuels, a very low sulfur marine gasoil (MGO) and a novel ultra-low sulfur heavy fuel oil (ULSHFO). In-use emissions are reported for the main engine when the ship traveled in within California's ECA, whereas emis...

The implementation of a comprehensive heavy-duty vehicle (HDV) Inspection and Maintenance (I/M) program could be a critical element in ensuring the emission control effectiveness of diesel HDVs over their full useful life. An on-board diagnostics (OBD)-based I/M program could be a cost-effective emission reduction program for diesel HDVs. Forty-fiv...

This study assessed particulate emissions characteristics from two flexible fuel vehicles (FFVs) equipped with port fuel injection (PFI) and gasoline direct injection (GDI) engines. Emissions testing was conducted over the Federal Test Procedure on E10, E51, and E83, and an iso-butanol blend (iBut55). The results showed significantly higher particu...

As the measurement of low levels of particulate matter (PM) and solid particulate number (PN) from light-duty vehicles becomes more critical, it is becoming more important to understand the potential impacts of exhaust transfer system contamination. This phenomenon occurs when, as it relates to vehicle emission testing, particles deposit and semi-v...

While the effects of fuel composition on primary vehicle emissions have been well studied, less is known about the effects on secondary aerosol formation and composition. The propensity of light-duty gasoline engines to form secondary aerosol and contribute to regional air quality burdens are of scientific interest. This study assessed secondary ae...

We evaluated the secondary aerosol formation from two current technology flex fuel vehicles (FFVs) equipped with gasoline direct injection engines when operated on different fuel formulation on a chassis dynamometer. This study explored the influence of ethanol fueling and aromatic concentration on secondary organic aerosol (SOA) production by util...

Vehicle activity is an integral component in the estimation of mobile source emissions and the study of emission inventories. In the Environmental Protection Agency’s (EPA’s) Motor Vehicle Emission Simulator (MOVES) model and the California Air Resources Board’s (CARB’s) Emission Factor (EMFAC) model, vehicle activity is defined for source types, i...

Fuel composition plays an important role on the particulate matter (PM) emissions formation from gasoline direct injection (GDI) engines. In this study, the impacts of gasoline chemical structure and physical properties on the particulate emissions were assessed for a fleet of five Tier 3 compliant GDI vehicles. All vehicles were tested on eight fu...

Gasoline composition is critical to the formation of regulated emissions and gaseous toxic pollutants from spark ignition engines equipped with direct injection fueling. This study investigated the impacts of varying aromatic and ethanol levels on the exhaust emissions of five gasoline direct injection (GDI) vehicles. A total of eight fuels were us...

This study assessed the gaseous and particulate emissions, as well as the toxicological properties of particulate matter (PM) from a flex fuel vehicle equipped with a wall-guided gasoline direct injection engine over triplicates cold-start and hot-start LA92 cycles. The vehicle was operated on a Tier 3 E10 fuel, an E10 fuel with higher levels of ar...

Real-world nitrogen oxides (NOx) emissions were estimated using on-board sensor readings from 72 heavy-duty diesel vehicles (HDDVs) equipped with Selective Catalytic Reduction (SCR) system in California. The results showed that there were large differences between in-use and certification NOx emissions, with 12 HDDVs emitted more than three times t...

The emissions of two ultralow NOx heavy-duty (HD) vehicles equipped with 0.02 g/bhp-hr low NOx natural gas (NG) engines were evaluated on a chassis dynamometer. This included a waste hauler and a city transit bus, each with a 0.02 g/bhp-hr NOx L9N near zero (NZ) natural gas engine. The vehicles were tested over a variety of different cycles, includ...

Direct primary emissions from light-duty passenger in the past 50 years have been reduced significantly. However, the potential of primary emissions to oxidize downwind of sources is challenging and not well understood. This study investigates the secondary aerosol (SA) forming potential of emissions generated from four wall-guided gasoline direct...

Activity data from 79 line-haul and vocational trucks were analyzed to estimate trip-averaged fuel consumption per distance driven and per work performed. The 79 trucks had engine model years ranging from 2008 to 2015 and average (±standard deviation) miles per gallon of 5.5 ± 1.7, which is comparable to other large fleet studies. Engine output wor...

The effects of photochemical aging on exhaust emissions from two light-duty vehicles with gasoline direct injection (GDI) engines equipped with and without catalyzed gasoline particle filters (GPFs) were investigated using a mobile environmental chamber. Both vehicles with and without the GPFs were exercised over the LA92 drive cycle using a chassi...

This study examined the influence of low-, mid-, and high-ethanol fueling, as well as the influence of the aromatic hydrocarbons in the fuel blend, on the regulated and greenhouse gas emissions, the mobile source air toxic pollutants, and the particulate emissions from a current model flexible fuel vehicle equipped with a gasoline direct injection...

Particulate matter (PM) mass measurement methodologies were improved considerably with the application of Title 40 Code of Federal Regulations Part 1065 for the 2007 standards for heavy-duty engines that emphasized PM. However, there is still a need to improve the understanding of and the confidence in mass measurements for light-duty vehicles, whi...

On-road heavy-duty diesel vehicles are a major contributor of oxides of nitrogen (NOx) emissions. In the US, many heavy-duty diesel vehicles employ selective catalytic reduction (SCR) technology to meet the 2010 emission standard for NOx. Typically, SCR needs to be at least 200 °C before a significant level of NOx reduction is achieved. However, th...

We assessed the physical, chemical and toxicological characteristics of particulate emissions from four light-duty gasoline direct injection vehicles when operated over the LA92 driving cycle. Our results showed that particle mass and number emissions increased markedly during accelerations. For three of the four vehicles tested, particulate matter...

With the reduction in PM emission standards for light duty vehicles to 3 mg/mi for current Federal and California standards and subsequently to 1 mg/mi in 2025 for California, the required PM measurements are approaching the detection limits of the gravimetric method. A “filter survey” was conducted with 11 laboratories, representing industry, agen...

Hybrid engine technology is a potentially important strategy for reduction of tailpipe greenhouse gas (GHG) emissions and other pollutants that is now being implemented for off-road construction equipment. The goal of this study was to evaluate the emissions and fuel consumption impacts of electric-hybrid excavators using a Portable Emissions Measu...

Real-world vehicle and engine activity data were collected from 90 heavy-duty vehicles in California, United States, most of which have engine model year 2010 or newer and are equipped with selective catalytic reduction (SCR). The 90 vehicles represent 19 different groups defined by a combination of vocational use and geographic region. The data we...

Knowledge of black carbon (BC) emission factors from ships is important 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. Six analytical methods measured the BC emissions in the exhaust of the marine engine operated at two load...

We assessed the gaseous, particulate, and genotoxic pollutants from two current technology gasoline direct injection vehicles when tested in their original configuration and with a catalyzed gasoline particulate filter (GPF). Testing was conducted over the LA92 and US06 Supplemental Federal Test Procedure (US06) driving cycles on typical California...

Recently, there are discussions about whether current sampling and measurement practices for the regulated gravimetric PM measurement are sufficiently accurate in quantifying PM at the proposed 3 and 1 mg/mi emission standards for light-duty vehicles. In this study, a series of modifications were made to the existing gravimetric PM measurement meth...

The regulated emissions of five 2012 and newer, low-mileage, heavy-duty Class 8 diesel trucks 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. NOx emissions over the Urban Dynamometer Driving...

Emissions from eight heavy-duty diesel trucks (HDDTs) equipped with three different exhaust aftertreatment systems (ATS) for controlling nitrogen oxide (NOx) emissions were quantified on a chassis dynamometer using driving schedules representative of stop-and-go and free-flow driving in metropolitan areas. The three control technologies were: 1) co...

The emissions and the potential health effects of particulate matter (PM) were assessed from two heavy-duty trucks with and without emission control aftertreatment systems when operating on CARB ultra-low sulfur diesel (ULSD) and three different biodiesel blends. The CARB ULSD was blended with soy-based biodiesel, animal fat biodiesel, and waste co...

The use of biodiesel and renewable diesel fuels in compression ignition engines and aftertreatment technologies may affect vehicle exhaust emissions. In this study two 2012 light-duty vehicles equipped with direct injection diesel engines, diesel oxidation catalyst (DOC), diesel particulate filter (DPF), and selective catalytic reduction (SCR) were...

Traffic-related pollutants are an ever-growing concern. However, the composition of particle emissions from new vehicle technologies using relevant current and prospective fuel blends is not known. This study tested four current and up-and-coming vehicle technologies with nine fuel blends with various concentrations of ethanol and iso-butanol. Vehi...

The reduction of emissions from diesel engines has been one of the primary elements in obtaining improvements in air quality and greenhouse gas reduction goals. Dimethyl carbonate (DMC) is an oxygenate fuel that can be used in petroleum diesel that is been lightly studied, but could provide significant reductions in particulate matter (PM) emission...

Integrated particle size distribution (IPSD) is a promising alternative method for estimating particulate matter (PM) emissions at low levels. However, a recent light-duty vehicle (LDV) emissions study showed that particle mass estimated using IPSD (MIPSD) with the TSI Engine Exhaust Particle Sizer (EEPS) Default Matrix was 56–75% lower than mass d...

In this paper, we report on TDL HCl measurements obtained at a coal-fi red power plant which indicate that there is a significant perturbation of the HCl absorption feature. A methodology was also developed to remediate this effect and provide accurate measurement that will meet the EPA precision and detection limits currently being developed for H...

Gaseous and particle emissions from construction engines contribute an important fraction of the total air pollutants released into the atmosphere and are gaining increasing regulatory attention. Robust quantification of nitrogen oxides (NOx) and particulate matter (PM) emissions are necessary to inventory the contribution of construction equipment...

In-lab and on-road emission comparisons are made between AVL’s M.O.V.E GAS PEMS 493 system and the UCR mobile emissions laboratory (MEL), which served as a Federal Reference Method (FRM) for comparison and validation. These comparisons are made for three different heavy-duty engines with NOx emission certification levels ranging from 0.27 g/kWh (0....

Gaseous and particulate matter (PM) emissions were assessed from two current technology heavy-duty vehicles operated on CARB ultra-low sulfur diesel (ULSD), hydrotreated vegetable oil (HVO) blends, and a biodiesel blend. Testing was performed on a 2014 model year Cummins ISX15 vehicle and on a 2010 model year Cummins ISB6.7 vehicle. Both vehicles w...

Implications: This study provides an evaluation of the operational performance of three methods/instruments, including TDL absorption spectroscopy (TDLAS), cavity ring down spectroscopy (CRDS), and FTIR spectroscopy, for the measurement of hydrochloric acid (HCl) over a range of real-world operating environments. The results showed good instrument...

The market for renewable fuels for transportation applications has grown significantly in recent years due to governmental regulations at the local, regional, and national levels throughout the world. One of the most important requirements for expanding the use of alternative fuels in transportation applications is to understand how these fuels mig...

The physical and chemical properties of aerosols emitted from vehicles can vary in composition under different driving conditions. Thus, characterizing ephemeral changes in aerosol cloud condensation nuclei (CCN) activity and apparent hygroscopicity for vehicle-testing procedures conducted over transient drive cycles can be challenging. To evaluate...

With funding from the California Energy Commission, the California Hybrid, Efficient and Advanced Truck Research Center, contracted with the University of California, Riverside's College of Engineering to evaluate the performance of a Class 5 battery electric urban delivery vehicle over two standardized driving cycles and a steady state range test...

Fast-sizing spectrometers, such as the TSI Engine Exhaust Particle Sizer (EEPS), have been widely used to measure transient particle size distributions of vehicle exhaust. Recently, size distributions measured during different test cycles have begun to be used for calculating suspended particulate mass; however, several recent evaluations have show...

Typical gasoline consists of varying concentrations of aromatic hydrocarbons and octane ratings. However, their impacts on Particulate Matter (PM) such as Black Carbon (BC) and water-soluble and insoluble particle compositions are not well defined. This study tests seven 2012 model year vehicles, which include one Port Fuel Injection (PFI) configur...

We assessed the emissions response of a fleet of seven light-duty gasoline vehicles to gasoline fuel aromatic content while operating over the LA92 driving cycle. The test fleet consisted of model year 2012 vehicles equipped with either port fuel injection (PFI) or direct injection (DI) technology. Three gasoline fuels were blended to meet a range...

Biofuels, such as ethanol and butanol, have been the subject of significant political and scientific attention, owing to concerns about climate change, global energy security, and the decline of world oil resources that is aggravated by the continuous increase in the demand for fossil fuels. This study evaluated the potential emissions impacts of d...

Emissions, fuel economy, and performance are determined over a light and a heavy driving cycle designed to represent the vehicles in-use driving patterns. The vehicles are 2010 class 8 Freightliner tractor trucks equipped with Cummins engines with Selective Catalytic Reduction and Diesel Particulate Filter emission control systems. The hybrid has l...

Vehicular emissions of particulate matter (PM) will change under different driving conditions and as higher levels of alternative fuels are blended with gasoline. In particular, the chemical composition and water-soluble components of PM below 2.5 μm can be modified. In this study, the emissions of three light-duty port-fuel injection (PFI) and two...

We examined the effects of different ethanol and iso-butanol blends on the gaseous and particulate emissions from two passenger cars equipped with spark ignition direct injection engines and with one spray-guided and one wall-guided configuration. Both vehicles were tested over triplicate FTP (Federal Test Procedure) and UC (Unified Cycles) using a...

This study investigated the effects of higher ethanol blends and an iso-butanol blend on the criteria emissions, fuel economy, gaseous toxic pollutants, and particulate emissions from two flexible-fuel vehicles equipped with spark ignition engines, with one wall-guided direct injection and one port fuel injection configuration. Both vehicles were t...

The relationship between ethanol and iso-butanol fuel concentrations and vehicle particulate matter emissions was investigated. This study utilized a gasoline direct injection (GDI) flexible fuel vehicle (FFV) with wall-guided fueling system tested with four fuels, including E10, E51, E83, and an iso-butanol blend at a proportion of 55% by volume....

Unlabelled: Continuous monitoring of exhaust flue gas has become a common practice in power plants in response to Federal Mercury and Air Toxics Standards (MATS) standards. Under the current rules, hydrochloric acid (HCl) is not continuously measured at most plants; however, MATS standards have been proposed for HCl, and tunable diode laser (TDL)...