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This review summarizes the latest developments in diesel emissions regarding regulations, engines, NOx (nitrogen oxides) control, particulate matter (PM) reductions, and hydrocarbon (HC) and CO oxidation. Regulations are advancing with proposals for PN (particle number) regulations that require diesel particulate filters (DPFs) for Euro VI in 2013-14, and SULEV (super ultra low emission vehicle) fleet average light-duty (LD) emissions likely to be proposed in California for ~2017. CO₂ regulations will also impact diesel engines and emissions, probably long into the future. Engine technology is addressing these needs. Heavy-duty (HD) research engines show 90% lower NOx at the same PM or fuel consumption levels as a reference 2007 production engine. Work is starting on HD gasoline engines with promising results. In light duty (LD), engine downsizing is progressing and deNOx is emerging as a fuel savings strategy.

The topic of CO₂ and fuel consumption reductions from vehicles is a very broad and complex issue, encompassing vehicle regulations, biofuel mandates, and a vast assortment of engine and vehicle technologies. This paper attempts to provide a high-level review of all these issues. Reducing fuel consumption appears not to be driven by the amount of hydrocarbon reserves, but by energy security and climate change issues. Regarding the latter, a plan was proposed by the United Nations for upwards of 80% CO₂ reductions from 1990 levels by 2050. Regulators are beginning to respond by requiring ~25% reductions in CO₂ emissions from light-duty vehicles by 2016 in major world markets, with more to come. The heavy-duty sector is poised to follow. Similarly, fuel policy is aimed at energy diversity (security) and climate change impacts. Emerging biofuel mandates require nominally 5-10% CO₂ life cycle emissions reductions by 2020.

This review paper summarizes major developments in vehicular emissions regulations and technologies from 2014. The paper starts with the key regulatory advancements in the field, including newly proposed Non-Road Mobile Machinery regulations for 2019-20 in Europe, and the continuing developments towards real driving emissions (RDE) standards. An expert panel in India proposed a roadmap through 2025 for clean fuels and tailpipe regulations. LD (light duty) and HD (heavy-duty) engine technology continues showing marked improvements in engine efficiency. Key developments are summarized for gasoline and diesel engines to meet both the emerging NOx and GHG regulations. HD engines are demonstrating more than 50% brake thermal efficiency using methods that can reasonably be commercialized. Next, NOx control technologies are summarized, including SCR (selective catalytic reduction), lean NOx traps, and combination systems. Emphasis is on durability and control.

This review paper summarizes major and representative developments in vehicular emissions regulations and technologies from 2015. The paper starts with the key regulatory advancements in the field, including newly proposed Euro 6 type regulations for Beijing, China, and India in the 2017-20 timeframe. Europe is continuing developments towards real driving emissions (RDE) standards with the conformity factors for light-duty diesel NOx ramping down to 1.5X by 2021. The California heavy duty (HD) low-NOx regulation is advancing and may be proposed in 2017/18 for implementation in 2023+. LD (light duty) and HD engine technology continues showing marked improvements in engine efficiency. Key developments are summarized for gasoline and diesel engines to meet both the emerging criteria and greenhouse gas regulations. LD gasoline concepts are achieving 45% BTE (brake thermal efficiency or net amount of fuel energy gong to the crankshaft) and closing the gap with diesel.

A production calibrated GTDI 1.6L Ford Fusion was used to demonstrate low HC, CO, NOx, PM (particulate mass), and PN (particulate number) emissions using advanced catalyst technologies with newly developed high porosity substrates and coated GPFs (gasoline particulate filters). The exhaust system consisted of 1.2 liters of TWC (three way catalyst) in the close-coupled position, and 1.6L of coated GPF in the underfloor position. The catalysts were engine-aged on a dynamometer to simulate 150K miles of road aging. Results indicate that ULEV70 emissions can be achieved at ∼$40 of PGM, while also demonstrating PM tailpipe performance far below the proposed California Air Resources Board (CARB) LEV III limit of 1 mg/mi. Along with PM and PN analysis, exhaust system backpressure is also presented with various GPF designs.

Diesel particle filters (DPF) have become a standard aftertreatment component for all current and future on-road diesel engines used in the US. In Europe the introduction of EUVI is expected to also result in the broad implementation of DPF's. The anticipated general trend in engine technology towards higher engine-out NOx/PM ratios results in a somewhat changing set of boundary conditions for the DPF predominantly enabling passive regeneration of the DPF. This enables the design of a novel filter concept optimized for low pressure drop, low thermal mass for optimized regeneration and fast heat-up of a downstream SCR system, therefore reducing CO₂ implications for the DPF operation. In this paper we will discuss results from a next-generation cordierite DPF designed to address these future needs.

This review paper summarizes major developments in vehicular emissions regulations and technologies (light-duty, heavy-duty, gasoline, diesel) in 2011. First, the paper covers the key regulatory developments in the field, including proposed criteria pollutant tightening in California; and in Europe, the newly proposed PN (particle number) regulation for direct injection gasoline engines, test cycle development, and in-use testing discussions. The proposed US LD (light-duty) greenhouse gas (GHG) regulation for 2017-25 is reviewed, as well as the finalized, first-ever, US HD (heavy-duty) GHG rule for 2014-17. The paper then gives a brief, high-level overview of key emissions developments in LD and HD engine technology, covering both gasoline and diesel. Emissions challenges include lean NOx remediation for diesel and lean-burn gasoline to meet both the emerging NOx and GHG regulations.

Examination of field-fractured windshields was conducted for purposes of determining the principle fracture mechanisms experienced in-use. Samples for the study were gathered both in the United States (New York) and in Europe (France) to explore whether the primary causes of failure were similar for the different geographic regions. In total, over two hundred individual field-fractures were obtained and examined for the study. Detailed fracture analysis of the parts was performed, and multiple fracture mechanisms were identified and quantified. It was found that the two most frequently observed failure modes were common for both regions with the most frequent cause (~70%) of fractures being due to sharp contact of the exterior ply, while Hertzian cone cracking of the outer ply was the second leading cause (~20%). Several other modes were also identified. Given that sharp impact fracture was the dominant observed failure mode, a high-speed, sharp impact test method was developed.

ExxonMobil, Corning and Toyota have collaborated on an Onboard Separation System (OBS) to improve gasoline engine efficiency and performance. OBS is a membrane based process that separates gasoline into higher and lower octane fractions, allowing optimal use of fuel components based on engine requirements. The novel polymer-ceramic composite monolith membrane has been demonstrated to be stable to E10 gasoline, while typically providing 20% yield of ∼100 RON product when using RUL 92 RON gasoline. The OBS system makes use of wasted exhaust energy to effect the fuel separation and provides a simple and reliable means for managing the separated fuels that has been demonstrated using several generations of dual fuel test vehicles. Potential applications include downsizing to increase fuel economy by ∼10% while maintaining performance, and with turbocharging to improve knock resistance.

Particulate emission from diesel engines is one of the most important pollutants in urban areas. As a result, particulate emission control from urban bus diesel engines using particle filter technology is being evaluated at several locations in the US. A project entitled “Clean Diesel Demonstration Program” has been initiated by NY City Transit under the supervision of NY State DEC and with active participation from several industrial partners. Under this program, several NY City transit buses with DDC Series 50 engines have been equipped with continuously regenerating diesel particulate filter system and are operating with ultra low sulfur diesel (< 30 ppm S) in transit service in Manhattan since February 2000. These buses are being evaluated over a 8-9 month period for operations, maintainability and durability of the particulate filter.

This paper gives a comprehensive overview of the current state-of-the-art in diesel emission control. The nature of diesel particulates is summarized. The variety of diesel particulate filter regeneration strategies that will become so important to filter application are reviewed. Filter retrofit and durability issues are addressed. DeNOx catalysts, SCR, NOx traps for diesel, and non-thermal plasma methods are summarized. Integrated NOx/PM systems are described. And reduction of exhaust toxics is discussed. The paper covers all major conferences in the year 2000 that occurred in the US and Europe. US and Europe.

To establish performance trends in ultra thin wall substrates and help support their selection criteria for designing catalytic converter systems, the light-off behavior of five Ultra Thin Wall ceramic substrates and two catalysts on an engine dynamometer are hereby examined. Modeling predictions are also compared to the engine results and the trends and implications are discussed. To quantify the performance of these different systems, light-off tests were performed on an engine dynamometer using a simulated FTP cycle. Five systems were evaluated (600/4, 600/3, 600/2, 900/2 and 1200/2) each with two different catalyst formulations. Engine bench aging was used to simulate typical aged conditions in the converter systems. Second by second emissions data for temperature, hydrocarbons and carbon monoxide, were used to evaluate the relative performances of the substrates.

In urban areas, particulate emission from diesel engines is one of the pollutants of most concern. As a result, particulate emission control from urban bus diesel engines using particle filter technology is being evaluated at several locations in the US. A project entitled, “Clean Diesel Vehicle Air Quality Project” has been initiated by NY City Transit under the supervision of NYSDEC and with active participation from several industry partners. Under this program, 25 NY City transit buses with DDC Series 50 engines have been equipped with continuously regenerating diesel particulate filter systems and have been operating with ultra low sulfur diesel (< 30 ppm S) in transit service in Manhattan since February 2000. These buses were evaluated over a 9 month period for operations, maintainability and durability of the particulate filter.

To meet the future emission targets for Diesel engines, one trend is the use of Catalyzed Diesel Particulate Filters (CDPF). Catalyzing the filter, however, alters filter behavior. In particular, alteration in filter permeability imparts a significant change in the filter's performance. To understand the impact of the catalyst coating on a DPF, engine tests have been conducted to measure the pressure drop across DPFs with different catalyst coatings, cell densities, and soot loadings. The tests were performed over a range of engine speeds and loads, with a corresponding range in exhaust flow rates and temperatures. A pressure drop model based on previous work for uncatalyzed filters has been modified and validated for CDPFs. To achieve optimum design for DPF's, a parametric study comparing the influence of catalyst, cell density, wall thickness, filter length and diameter was done.

This review paper summarizes major and representative developments in vehicle engine efficiency and emissions regulations and technologies from 2016. The paper starts with the key regulatory developments in the field, including newly proposed European RDE (real driving emissions) particle number regulations, and Euro 6 type regulations for China and India in the 2020 timeframe. China will be tightening 30-40% relative to Euro 6 in 2023. The California heavy duty (HD) low-NOx regulation is advancing and the US EPA is anticipating developing a harmonized proposal for implementation in 2023+. The US also finalized the next round of HD GHG (greenhouse gas) regulations for 2021-27, requiring 5% engine CO2 reductions. LD (light duty) and HD engine technology continues showing marked improvements in engine efficiency. Key developments are summarized for gasoline and diesel engines to meet both the emerging criteria and greenhouse gas regulations.

With the introduction of the current EU5 standards the diesel particulate filter has become a key element in the aftertreatment of diesel passenger cars. The upcoming future emission standards target primarily a further reduction in NOx emission as well as reduced fleet average CO₂ emissions. Although the particulate filter has no direct influence on the reduction of these species, the needs of future aftertreatment systems impose additional requirements on advanced filter technologies. In this paper we are introducing two new filter products based on a new low porosity aluminum titanate family that complement the current DuraTrap® AT filter products. The new products offer the potential for an increased soot mass limit or a significant reduction in pressure drop. The enhanced performance of the new filter products is discussed and demonstrated in a large number of experimental data obtained in engine bench tests.

The motorcycle emissions regulations for both two-stroke and four-stroke engines, which are receiving worldwide attention, will go into effect in the very near future. To meet these regulations, the motorcycles will require a catalyst in conjunction with the muffler due to space limitations. The combination of high engine speeds, high vibrational acceleration, high HC and CO emissions, high oxidation exotherms, and stringent durability requirements, points to cordierite ceramic substrate as an ideal catalyst support. However, as an integral unit within the muffler, its packaging design must be capable of withstanding isothermal operating conditions which may exceed the upper intumescent temperature limit of the ceramic mat. This paper describes a durable packaging design for the ceramic catalyst which employs a hybrid ceramic mat, special end rings and gaskets, and high strength stainless steel can.

Improved designs of extruded metal electrically heated catalysts (EHC) in combination with a traditional converter achieved the California ultra-low emission vehicle (ULEV) standard utilizing 50% less electrical energy than previous prototypes. This energy reduction is largely achieved by reducing the mass of the EHC. In addition to energy reduction, the battery voltage is reduced from 24 volts to 12 volts, and the power is reduced from 12 kilowatts to 3 kilowatts. Also discussed is the impact EHC mass, EHC catalytic activity, and no EHC preheating has on non-methane hydrocarbon emissions, energy requirements, and power requirements.

The design, performance and optimization of the extruded electrically heated metal converter have recently been published(1,2). The present paper focuses on the physical durability of extruded metal EHC support at high temperature representative of operating conditions. The mechanical, thermal, creep and fatigue properties of Fe-Cr-Al honeycomb structure over 25°-1000°C temperature range are reported. In addition, the stresses arising from mounting and thermal loads are computed via finite element analysis and compared with the high temperature strength of extruded metal EHC support. A safe design stress which predicts 192,000 kilometer durability is estimated from high temperature fatigue behavior of extruded Fe-Cr-Al honeycomb structure.

Low mass extruded electrically heated catalysts (EHC) followed directly by light-off and main converters resulted in non-methane hydrocarbon emissions (NMHC) between .020 and .023 g/mi at power levels as low as 1 kw and energy levels as low as 4 whr. These results were achieved on a 1993, 2.2 liter vehicle. The success of this system is due to rapid heat up of the catalyzed surface areas of both the heater and light-off converter. The energy added to the exhaust from both the heater and the light-off is then efficiently transferred to the main converter. In addition, the impact of power and energy on NMHC levels was determined. The Ultra-Low Emissions Vehicle (ULEV) standard was also achieved with uncatalyzed heaters and on a 1990, 3.8 L vehicle. The new California Low Emission Vehicle (LEV) and Ultra Low Emission Vehicle (ULEV) standards require a significant reduction in tail pipe emissions compared to current standards.