Criteria pollutant and greenhouse gas emissions from CNG transit buses equipped with three-way catalysts compared to lean-burn engines and oxidation catalyst technologies

Yoon, Seungju; Collins, John; Thiruvengadam, Arvind; Gautam, Mridul; Herner, Jorn; Ayala, Alberto

doi:10.1080/10962247.2013.800170

Cited by 67 publications

(57 citation statements)

References 20 publications

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“…Despite higher CO emissions from the CNG compared to diesel vehicles, brake-specific emissions were at least three times below the engine dynamometer certification standards. Earlier chassis dynamometer testing of TWCequipped CNG buses with MY 2007-2011 Cummins 8.9-L engines reported CO emissions between 6 and 27 g/mi over various vocational and standard chassis dynamometer driving cycles [30,31]; per-mile emissions reported from the 12-L CNG engine in this study was 7.6-14.4 g/mi indicating comparable levels of control by stoichiometric combustion and TWC aftertreatment. Generally for both CNG and diesel-powered vehicles in this study, CO emissions were lower for routes with higher vehicle load and speeds, and emissions were slightly higher for lowerspeed driving in Near-Dock and Local Drayage Routes.…”

Section: Co Emissionsmentioning

confidence: 75%

“…While these THC results are an order of magnitude higher than the NMHC certification standard, they are unlikely to indicate an exceedance of the NMHC standard due to cross sensitivity of the THC detector to methane, which has been shown in previous studies to account for ∼95 % of the THC signal for stoichiometric CNG engines equipped with TWC [30]. …”

Section: Thc Emissionsmentioning

confidence: 93%

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Real-World Emissions from Modern Heavy-Duty Diesel, Natural Gas, and Hybrid Diesel Trucks Operating Along Major California Freight Corridors

Quiros

Thiruvengadam

Pradhan

et al. 2016

Emiss. Control Sci. Technol.

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Emissions were measured from seven heavy-duty (HD) on-road vehicles that were operated along six common route types used for freight transport in California. All vehicles had engines that were certified to the 0.01 g/bhp-h particulate matter (PM) and either a 0.2, 0.3, or 2.3 g/bhp-h nitrogen oxide (NOx) standard. Diesel vehicles had low carbon monoxide (CO) and total hydrocarbon (THC) emissions below brake-specific standards, with route averages ranging from 0.24 to 3.35 g CO/ mi and from 0.02 to 0.45 g THC/mi. Diesel vehicles equipped with selective catalytic reduction (SCR) had route average NOx emissions ranging from 0.58 to 3.99 g/mi (0.16 to 0.96 g/bhp-h). NOx emissions were less route-dependent for the one vehicle with a 12-L compressed natural gas (CNG) engine and threeway catalyst (TWC), with route averages ranging from 0.16 to 0.46 g/mi (0.06 to 0.13 g/bhp-h). The ranking of certification NOx emissions for the seven engines reported during enginedynamometer-based certification was not maintained during real-world testing; for example, highway driving NOx emissions were lower than certification values for some engine families and higher than certification values for others. Route-average gravimetric particulate matter (PM) emissions ranged from 4 to 12 mg/ mi, which on a brake-specific basis were at least two times below the 0.01 g/bhp-h standard. Ion speciation of PM emissions indicated that the most prevalent species were sulfate (SO 4 2− ) for the model year (MY) 2007 diesel vehicle equipped with a diesel particulate filter (DPF) and no SCR, nitrate (NO 3 − ) for conventional diesel vehicles with a DPF and SCR, and sodium (Na + ) was the most abundant species for the CNG vehicle. NOx and PM emissions were compared to, and show generally good agreement with, the latest California mobile source model (EMFAC2014).

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Section: Co Emissionsmentioning

confidence: 75%

Section: Thc Emissionsmentioning

confidence: 93%

Real-World Emissions from Modern Heavy-Duty Diesel, Natural Gas, and Hybrid Diesel Trucks Operating Along Major California Freight Corridors

Quiros

Thiruvengadam

Pradhan

et al. 2016

Emiss. Control Sci. Technol.

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“…We take the ratios between the emissions factors for diesel and CNG buses and apply them to diesel trucks and get CNG truck factors. Before doing so, as shown in Figure 3, we adjust CNG bus emissions factors based on vehicle test data (Yoon et al 2013;WVU 2014) to reflect recent advances in CNG vehicles such as stoichiometric engine equipped with a three-way catalyst (TWC) system. MOVES also provides no emissions factors for hybrid vehicles.…”

Section: Electric Grid (Average and Marginal)mentioning

confidence: 99%

“…Adjustment factors for MOVES2014-based tail-pipe emissions rates for CNG medium-duty truck. Two sets of vehicle test data(Yoon et al 2013; WVU 2014) for EPA Heavy-Duty Urban Dynamometer Driving Schedule (HD-UDDS) were used for reference (average of the two data sets).…”

mentioning

confidence: 99%

Parametric modeling approach for economic and environmental life cycle assessment of medium-duty truck electrification

Lee

Thomas

2017

Journal of Cleaner Production

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Using a parametric modeling approach, we evaluate economic and environmental life cycle trade-offs of medium-duty electric trucks in comparison with nine non-electric technologies (e.g., conventional diesel, biodiesel, compressed natural gas, etc.) for U.S. model year 2015. Life cycle results for electric trucks vary strongly with weighted positive kinetic energy, whereas those for non-electric trucks vary the most with average trip speed. Our parametric life cycle assessment models explain 91%-98% of the variability in life cycle inventory and impact assessment results, revealing "how" and "why" the tradeoffs of truck electrification change with different input conditions. In terms of cost, whether total cost of ownership or also including health and climate impact costs, model year 2015 battery electric trucks in severe applications such as urban driving provide positive and robust net benefits in many areas of the U.S. However, for typical operations, petroleum diesel with idle reduction or hybrid-electric technology provide the largest overall life cycle cost benefit. Battery electric, idle reduction, and hybrid trucks emit lower life cycle greenhouse gas emissions across the board in comparison with the other technologies. Despite lower carbon-intensity, electric trucks tend to be water-intensive because of cooling water consumption for thermo-electric power plants. Hybrid trucks create higher NOx emissions and thus larger associated environmental impacts. Idle reduction is beneficial to urban-type applications. Compressed natural gas trucks are the least waterintensive but may not reduce greenhouse gas emissions. Using marginal rather than average factors for electric grid emissions calculations doesn't change the overall life cycle comparisons. Improving driving behavior has universally positive effects for which the exact magnitude and sensitivity depend on environmental impact indicators and technologies.

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“…However, stoichiometric engines with TWCs produce higher CO emissions than lean-burn engines [14]. Particulate Matter (PM) emissions from both stoichiometric and lean-burn combustion NG engines are very low due to the almost homogeneous combustion of the air-gas mixture, and the absence of large hydrocarbon chains and aromatics in the fuel [15]. For NGVs, one issue that has been shown to be important with respect to emissions is the effect of changing the composition of the fuel.…”

Section: Objectivementioning

confidence: 99%

Investigation of Combustion Phenomena in a Single-Cylinder Spark-Ignited Natural Gas Engine with Optical Access

Padmanaban¹

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More demanding efficiency and emissions standards for internal combustion (IC) engines require novel combustion strategies, alternative fuels, and improved after-treatment systems. However, their development depends on improved understanding of in-cylinder processes. For example, the lower efficiency of conventional spark-ignited (SI) natural-gas (NG) engines reduces their utilization in the transportation sector. Single-cylinder optical-access research engines allow the use of non-intrusive visualization techniques that study in-cylinder flow, fuel-oxidizer mixing, and combustion and emissions phenomena under conditions representative of production engines. These visualization techniques can provide qualitative and quantitative answers to fundamental combustion-phenomena questions such as the effects of engine design, operating conditions, fuel composition, fuel delivery strategy, and ignition techniques. The thesis is divided in two main parts. The first part focuses on the setup of a single-cylinder research engine with optical access including the design of its control system and the acquisition of in-cylinder pressure data and high-speed combustion images. The second part focuses on measurements of the turbulent flame speed using the high-speed combustion images. Crank-angle-resolved images of methane combustion were taken with a high-speed CMOS camera at a rate of 15,000 Hz. The optical engine was operated in a skip-firing mode (one fired cycle followed by 5 motored cycles) at 900 RPM and a load of 5.93 bar IMEP. The images show that flow turbulence and flame stretch resulted in flame velocities several order of magnitude higher compared to the laminar flame velocity. In addition, both in-cylinder pressure and optical data were used to determine the cycle-to cycle variability of the combustion phenomena. iii Dedication This thesis is dedicated to my beloved parents, Dr.Padmanaban, and Beena Padmanaban First and foremost, I would like to thank my research advisor Dr. Cosmin Dumitrescu for his support, knowledge and all the friendship he shared with me right from the beginning. Everything he taught me both, in academics and building me as a person will surely stay with me and help me progress in my future career. His perseverance in work have always strongly motivated me to put in a lot of efforts and set an example to my colleagues in the laboratory. I am very grateful to him for teaching me the difference between a scientific and an engineering work, helping me start transforming into a good researcher. On a lighter note, I am very thankful to him for having funded me three long semesters in my master's study. I would like to express my gratitude to Dan Carder for having initially hired me to the CAFEE, and help me settle down to work with optical engines research project. My heartfelt thanks are due to my committee member Dr. Arvind Thiruvengadam for having been a good friend and a wonderful source of inspiration. With his stature and knowledge, nobody I could think of to have been this modest, helpful and...

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Criteria pollutant and greenhouse gas emissions from CNG transit buses equipped with three-way catalysts compared to lean-burn engines and oxidation catalyst technologies

Cited by 67 publications

References 20 publications

Real-World Emissions from Modern Heavy-Duty Diesel, Natural Gas, and Hybrid Diesel Trucks Operating Along Major California Freight Corridors

Real-World Emissions from Modern Heavy-Duty Diesel, Natural Gas, and Hybrid Diesel Trucks Operating Along Major California Freight Corridors

Parametric modeling approach for economic and environmental life cycle assessment of medium-duty truck electrification

Investigation of Combustion Phenomena in a Single-Cylinder Spark-Ignited Natural Gas Engine with Optical Access

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