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This review paper summarizes major developments in vehicular emissions regulations and technologies (light-duty, heavy-duty, gasoline, diesel) in 2012. First, the paper covers the key regulatory developments in the field, including finalized criteria pollutant tightening in California; and in Europe, the development of real-world driving emissions (RDE) standards. The US finalized LD (light-duty) greenhouse gas (GHG) regulation for 2017-25. The paper then gives a brief, high-level overview of key developments in LD and HD engine technology, covering both gasoline and diesel. Marked improvements in engine efficiency are summarized for gasoline and diesel engines to meet both the emerging NOx and GHG regulations. HD engines are just starting to demonstrate 50% brake thermal efficiency. NOx control technologies are then summarized, including SCR (selective catalytic reduction) with ammonia, and hydrocarbon-based approaches.

The destruction of low concentrations (<600 ppm) of nitric oxide using a low-temperature, dielectric barrier/packed-bed corona reactor has been studied. We compare the chemistry and energy efficiencies observed using various packing materials in warm moist air under oxidative (lean-burn) conditions. Measurements of NO and NOx removal in the effluent gas were made as a function of energy dissipated in the reactor. Changes in the observed fate of NO as a function of the packing material are discussed.

China 6 (CN6) emission legislation for light duty vehicles was published in 2016, which introduced real driving emissions (RDE) requirements for new type-approval content. Nitrogen oxides (NOx) and particle number (PN) of RDE test are required to be monitored and reported from July 2020 in CN6a phase, fulfilled from July 2023 in CN6b phase. To meet the PN limitation of CN6 RDE, the optimized engine combustion and advanced emission control system like gasoline particle filter (GPF) are encouraged. Compared to traditional vehicle platform emission compliance which could be done in lab, much more vehicle development and validation efforts are expected on the open road for RDE compliance. High cost and complexity are expected to conduct a complete validation test matrix covering all the RDE critical boundary conditions on the open road.

This paper examines the relative thermal shock requirements for ceramic catalysts in underbody vs. close-coupled positions. The higher operating temperature in the latter position may imply higher coefficient of thermal expansion and higher thermal stresses, depending on substrate/washcoat interaction, than those for underbody position. An analysis of thermal stresses, using relevant physical properties and temperature gradients, is presented for both close-coupled and underbody catalysts. Three different high temperature close-coupled catalysts, employing advanced ceramic substrates with 600/3, 600/4 and 900/2 cell structure, and an underbody catalyst with 400/6.5 standard ceramic substrate are examined. Such an analysis is valuable for designing the optimum aspect ratio (length/diameter) and packaging system, which will minimize thermal and mechanical stresses over the desired lifetime of 120K vehicle miles.

The hole stretchability of two Aluminum Alloys (AA6111 and AA6022) are studied by using a two stages integrated finite element framework where the edge geometry and edge damages from the hole piercing processes were considered in the subsequent hole expansion processes. Experimentally it has been found that AA6022 has higher hole expansion ratios than those of AA6111. This observation has been nicely captured by finite element simulations. The main cause of differences have been identified to the volume fractions of the random distributed second phase hard particles which play a critical role in determining the fracture strains of the materials.

Automobile body and truck cab structures are composed primarily of stampings formed from monolithic and constant gage blanks. Cost and weight penalties can arise when strength or other requirements in one small area of the part leads to the use of a material or gage that is overmatched to the needs of the rest of the stamping. Tailor Welded Blanks (TWBs) are hybrid sheet products composed of either different materials or different thickness sheets that are joined together, then subjected to a stamping operation to create a formed assembly. The strategy is employed generally to save weight and material costs in the formed assembly by placing higher strength or thicker sections only where needed. The forming or stamping process requires the joint to be severely deformed along with the parent sheets. Aluminum TWBs for automotive applications are particularly problematic because of the low formability of aluminum weld metal.

The effect of hydroforming on the mechanical properties and dynamic crush behaviors of tapered aluminum 6063-T4 tubes with octagonal cross section are investigated by experiments. First, the thickness profile of the hydroformed tube is measured by non-destructive examination technique using ultrasonic thickness gauge. The effect of hydroforming on the mechanical properties of the tube is investigated by quasi-static tensile tests of specimens prepared from different regions of the tube based on the thickness profile. The effect of hydroforming on the dynamic crush behaviors of the tube is investigated by axial crush tests under dynamic loads. Specimens and tubes are tested in two different heat treatment conditions: hydroformed-T4 (as-received) and T6. The results of the quasi-static tensile tests for the specimens in hydroformed-T4 condition show different amounts of work hardening depending on the regions, which the specimens are prepared from.

Diesel fuels derived from different types of crude oil can exhibit different chemistry while still meeting market requirements and specifications. Oil sands derived fuels typically contain a larger proportion of cycloparaffinic compounds, which result from the cracking and hydrotreating of bitumens in the crude. In the current study, 17 refinery streams consisting of finished fuels and process streams were obtained from a refinery using 100% oil sands derived crude oil. All samples except one met the ULSD standard of 15 ppm sulfur. The samples were characterized for properties and chemistry and run in a simple premixed HCCI engine using intake heating for combustion phasing control. Results indicate that the streams could be equally well characterized by chemistry or properties, and some simple correlations are presented. Cetane number was found to relate mainly to mono-aromatic content and the cycloparaffins did not appear to possess any unique diesel related chemical effects.

Sustained NOx reduction at low temperatures, especially in the 150-200 °C range, shares some similarities with the more commonly discussed cold-start challenge, however, poses a number of additional and distinct technical problems. In this project, we set a bold target of achieving and maintaining 90% NOx conversion at the SCR catalyst inlet temperature of 150 °C. This project is intended to push the boundaries of the existing technologies, while staying within the realm of realistic future practical implementation. In order to meet the resulting challenges at the levels of catalyst fundamentals, system components, and system integration, Cummins has partnered with the DOE, Johnson Matthey, and Pacific Northwest National Lab and initiated the Sustained Low-Temperature NOx Reduction program at the beginning of 2015 and completed in 2017.

Sub-23nm particles emission from the light-duty vehicle is widely discussed now and possible to be counted into the next stage emission legislation, such as Euro7. In this article, 16 China6 gasoline vehicles were tested over the WLTC and two surrogate RDE lab cycles for particulate number (PN) emission, the difference between PN23 (particle size >23nm) and PN10 (particle size>10nm) emission was analyzed. Testing results showed that the average PN10 emission increased 59% compared to PN23, which will bring great challenges for those vehicles to meet the future regulation requirement if sub-23nm particle is counted. The sub-23nm particles emission was proportional to the PN23 particles emission and generated mostly from the cold start or the transient engine conditions with rich combustion. Compared to the proposal of Euro 7, PN10 emission from some tested vehicles will need further two orders of magnitude reduction.

We developed a non-destructive and non-contact method for measuring stress at the mid-plane of tempered glass plates that uses Bragg scattering from a pair of thermal gratings. These gratings are formed by 1064 nm beams from a seeded Nd:YAG laser and we measure the polarization state of light from a 532 nm beam that scatters from both these thermal gratings. The change in polarization of the doubly scattered light with separation between the two gratings allows measurement of the in-plane stress. Stress measurements are reported.

A slipstream of exhaust from a Caterpillar 3126B engine was diverted into a plasma-catalytic NOx control system in the space velocity range of 7,000 to 100,000 hr-1. The stream was first fed through a non-thermal plasma that was formed in a coaxial cylinder dielectric barrier discharge reactor. Plasma treated gas was then passed over a catalyst bed held at constant temperature in the range of 573 to 773 K. Catalysts examined consisted of γ-alumina, indium-doped γ-alumina, and silver-doped γ-alumina. Road and rated load conditions resulted in engine out NOx levels of 250 - 600 ppm. The effects of hydrocarbon level, catalyst temperature, and space velocity are discussed where propene and in one case ultra-low sulfur diesel fuel (late cycle injection) were the reducing agents used for NOx reduction. Results showed NOx reduction in the range of 25 - 97% depending on engine operating conditions and management of the catalyst and slipstream conditions.

Recently, SiC has been investigated and pursued as an alternative material for diesel particulate filter (DPF) applications. SiC has acceptable physical properties such as good thermal conductivity, refractoriness, and chemical durability. Materials for DPF applications require a particular mean pore size, porosity, and permeability. In addition, these material attributes must be coupled to an appropriate thermal design so that the filter can survive the extreme temperature gradients generated during the regeneration process. In this report several approaches to making porous SiC will be discussed and performance data based on material properties and thermal design will be presented.

The catalytic activity of selected materials (BaY and NaY zeolites, and γ-alumina) for selective NOx reduction in combination with a non-thermal plasma was investigated. Our studies suggest that aldehydes, formed during the plasma treatment of simulated diesel exhaust, are the important species for the reduction of NOx to N2. Indeed, all materials that are active in plasma-assisted catalysis were found to be very effective for the thermal reduction of NOx in the presence of aldehydes. For example, the thermal catalytic activity of a BaY zeolite with aldehydes gives 80-90% NOx removal at 250°C with 200ppm NOx at the inlet and a VHSV=12,000 h-1. The hydrocarbon reductants, n-octane and 1-propyl alcohol, have also shown high thermal catalytic activity for NOx removal over BaY, NaY and γ-alumina.

We describe a study to identify potential biofuels that enable advanced spark ignition (SI) engine efficiency strategies to be pursued more aggressively. A list of potential biomass-derived blendstocks was developed. An online database of properties and characteristics of these bioblendstocks was created and populated. Fuel properties were determined by measurement, model prediction, or literature review. Screening criteria were developed to determine if a bioblendstock met the requirements for advanced SI engines. Criteria included melting point (or cloud point) < -10°C and boiling point (or T90) <165°C. Compounds insoluble or poorly soluble in hydrocarbon were eliminated from consideration, as were those known to cause corrosion (carboxylic acids or high acid number mixtures) and those with hazard classification as known or suspected carcinogens or reproductive toxins.

Mixing controlled compression ignition, i.e., diesel engines are efficient and are likely to continue to be the primary means for movement of goods for many years. Low-net-carbon biofuels have the potential to significantly reduce the carbon footprint of diesel combustion and could have advantageous properties for combustion, such as high cetane number and reduced engine-out particle and NOx emissions. We developed a list of over 400 potential biomass-derived diesel blendstocks and populated a database with the properties and characteristics of these materials. Fuel properties were determined by measurement, model prediction, or literature review. Screening criteria were developed to determine if a blendstock met the basic requirements for handling in the diesel distribution system and use as a blend with conventional diesel. Criteria included cetane number ≥40, flashpoint ≥52°C, and boiling point or T90 ≤338°C.

In order to effectively use CAE to meet wind noise NVH targets, it is important to understand the main wind noise transfer paths. Testing confirmation of these paths by means of acoustic wind tunnel test is expensive and not always available. An on-road test procedure including a “windowing” method (using barriers) was developed to measure wind noise contribution at important higher frequencies through the main transfer paths, which were shown by test to be the glasses at a typical operating condition in which wind noise was dominant. The test data was used to correlate a full-vehicle SEA (Statistical Energy Analysis) model that placed emphasis on the glass properties, main noise transfer paths, and interior acoustic spaces while simplifying all other transmission paths. A method for generating wind noise loads was developed using measured glass vibration data, exterior pressure data, and interior acoustic data.

Driven by the worldwide automotive emission regulations, ceramic substrates were developed to serve as catalyst support. Since the introduction of Standard wall substrates in 1974, substrates with thinner walls and higher cell densities have been developed to meet the tighter emission requirements; Worldwide, the amount of Thinwall and Ultrathinwall substrates in series applications is increasing continuously. The properties of the substrates determine their performance regarding pressure drop, heat-up and conversion efficiency. These properties are analyzed, as well as the packaging process for Thinwall and Ultrathinwall substrates; A new packaging technique with lower pressure load is described.

Continuous improvement in vehicle emissions is necessary to meet ever tightening regulations. These regulations are advancing in both passenger and light truck vehicle markets, currently at different rates. Divergent design requirements and target markets for these platforms create unique conditions for aftertreatment needs. To understand the performance of various products in these categories and the potential for optimization, we examine various ultrathin-wall products in the context of a close-coupled configuration in a SULEV vehicle. In addition, these comparisons are carried over to a larger platform to show the performance trends in the context of the sport utility vehicle category. This study considers converter performance in FTP tests, examining bag data, light-off behavior, pressure drop comparisons and front and rear converter contributions. Conclusions are drawn regarding the optimization of converter substrate selection for various target design criteria

A noticeable degree of inconsistent forming behaviors has been observed for the 1st generation advanced high strength steels (AHSS) in production, and they appear to be associated with the inherent microstructural-level inhomogeneities for various AHSS. This indicates that the basic material property requirements and screening methods currently used for the mild steels and high strength low alloys (HSLA) are no longer sufficient for qualifying today's AHSS. In order to establish more relevant material acceptance criteria for AHSS, the fundamental understandings on key mechanical properties and microstructural features influencing the local formability of AHSS need to be developed. For this purpose, in this study, DP980 was selected as model steels and eight different types of DP980 sheet steels were acquired from various steel suppliers.