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As greenhouse gas regulations continue to tighten, more opportunities to improve engine efficiency emerge, including exhaust gas heat recovery. Upon cold starts, engine exhaust gases downstream of the catalysts are redirected with a bypass valve into a heat exchanger, transferring its heat to the coolant to accelerate engine warm-up. This has several advantages, including reduced fuel consumption, as the engine’s efficiency improves with temperature. Furthermore, this accelerates readiness to defrost the windshield, improving both safety as well as comfort, with greater benefits in colder climates, particularly when combined with hybridization’s need for engine on-time solely for cabin heating. Such products have been in the market now for several years; however they are bulky, heavy and expensive, yielding opportunities for competitive alternatives.

Stringent global emissions legislations demand effective NOx reduction strategies for both the engine as well as the aftertreatment. Diesel applications have previously applied Lean NOx Catalysts (LNCs) [1, 2], but their reduction efficiency and longevity have been far less than that of the competing ammonia-based SCR systems, such as urea [3]. A catalyst has been developed to significantly reduce NOx emissions, approaching 60% with ULSD and exceeding 95% with E85. Both thermal and sulfur aging are applied, as well as on-engine aging, illustrating resilient performance to accommodate necessary life requirements. A robust system is developed to introduce both ULSD from the vehicle's tank as well as E85 (up to 85% ethanol with the balance being gasoline) from a moderately sized supplemental tank, enabling extended mileage service intervals to replenish the reductant, as compared with urea, particularly when coupled with an engine-out based NOx reduction technology, such as EGR.

Establishing a certain maintenance-free time period regarding modern diesel exhaust emission control systems is of major importance nowadays. One of the most serious problems Diesel Particulate Filter (DPF) manufacturers face concerning system's durability is the performance deterioration due to the filter aging because of the accumulation of the ash particles. The evaluation of the effect of the ash aging on the filter performance is a time and cost consuming task that slows down the process of manufacturing innovative filter structures and designs. In this work we present a methodology for producing filter samples aged by accumulating ash produced by the controlled pyrolysis of oil-fuel solutions. Such ash particles bear morphological (size) and compositional similarity to ash particles collected from engine aged DPFs. The ash particles obtained are compared to those from real engine operation.

Although engine emissions per vehicle have been reduced for twenty years with technical developments in the fields of engine, after-treatment technologies and fuels the urban air pollution problem still exists in many cities around the world. Forthcoming emission regulations will require further development of new complex technologies to reach low emissions. On-board driving assessment of such technologies offers significant advantages in the development phase of novel emission reduction. In this paper we present the design, development and commissioning of a mobile laboratory able to monitor on-board along the exhaust line gaseous and particulate pollutants as well as measure these pollutants in the ambient environment around the vehicle.

In this paper a fast DPF screening procedure is proposed using small-scale filter samples of different technologies in a well-controlled environment but under realistic engine exhaust conditions. The DPF samples are evaluated in a specially built Multi-Reactor Assembly (MRA) with respect to their flow resistance, filtration efficiency, soot loading behavior, soot oxidation behavior, as well as their ash induced ageing behavior.

The objective of this study is the design, construction and evaluation of a Selective Particle Size (SPS) sampler able to provide continuous delivery of diesel soot particles of specific size ranges. The design of the sampler combines principles of aerosol transport phenomena and separation technologies. Particles smaller than a given size are removed from the exhaust by diffusional deposition, while removal of particles above a given size is achieved by low pressure inertial impaction. The main application of the developed sampler is the exposure of biological samples such as cell and tissue cultures to selected sizes of diesel exhaust particles. By applying the SPS sampler to diesel exhaust it is demonstrated that it is possible to obtain two aerosol streams with widely separated particle size distributions (of nanometric dimensions), suitable for biological exposure studies.

A computational lumped parameter model (MTU-Filter-Lumped) was developed to describe the performance of diesel particulate filters (DPFs) during loading and regeneration processes. The model was formulated combining three major sub-models: a filtration model, a pressure drop model, and a mass and an energy balance equation for the total filter volume. The first two sub-models have been widely validated in the literature, while the third sub-model is introduced and combined with the first two sub-models in the present study. The three sub-models combined can give a full description of diesel particulate filter behavior during loading and regeneration processes, which was the objective of the present work. The total combined lumped parameter model was calibrated using experimental data from the literature covering a range of experimental conditions, including different catalytic regeneration means and engine operating conditions.

Novel catalytic coatings with a variety of methods based on conventional and novel synthesis routes are developed for Diesel Particulate Filters (DPFs). The developed catalytic composition exhibits significant direct soot oxidation as evaluated by reacting mixtures of diesel soot and catalyst powders in a thermogravimetric analysis apparatus (TGA). The catalyst composition was further deposited on oxide and non-oxide porous filter structures that were evaluated on an engine bench with respect to their filtration efficiency, pressure drop behavior and direct soot oxidation activity under realistic conditions. The effect of the catalyst amount on the filtration efficiency of non-oxide filters was also investigated. Evaluation of the indirect soot oxidation was conducted on non-oxide catalytic filters coated with precious metal.

A new platform of advanced ceramic composite filter materials for diesel particulate matter and exhaust gas emission control has been developed. These materials exhibit high porosity, narrow pore-size distribution, robust thermo-mechanical strength, and are extruded into high cell density honeycomb structures for wall-flow filter applications. These new high porosity filters provide a structured filtration surface area and a highly connected wall pore space which is fully accessible for multi-phase catalytic reactions. The cross-linked microstructure (CLM™) pore architecture provides a large surface area to host high washcoat/catalyst loadings, such as those required for advanced multi-functional catalysts (4-way converter applications).

Asymmetric and Variable Cell (AVC) geometry Diesel Particulate Filters (DPF) occupy an increasing portion of the DPFs currently offered by various DPF manufacturers, aiming at providing higher filtration area in the same filter volume to meet demanding emission control applications for passenger cars but also for heavy duty vehicles. In the present work we present an approach for designing and optimizing such DPFs by providing a quantitative description of the flow and deposition of soot in these structures. Soot deposit growth dynamics in AVC DPFs is studied computationally, primary and secondary flows over the inlet channels cross-sectional perimeters are analyzed and their interactions are elucidated. The result is a rational description of the observed growth of soot deposits, as the flow readjusts to transport the soot particles along the path of least resistance (which is not necessarily the shortest geometric path between the inlet and outlet channel, i.e. the wall thickness).

To meet EPA Tier IV large diesel engine emission targets, intensive development efforts are necessary to achieve NOx reduction and Particulate Matter (PM) reduction targets [1]. With respect to NOx reduction, liquid urea is typically used as the reagent to react with NOx via SCR catalyst [2]. Regarding to PM reduction, additional heat is required to raise exhaust temperature to reach DPF active / passive regeneration performance window [3]. Typically the heat can be generated by external diesel burners which allow diesel liquid droplets to react directly with oxygen in the exhaust gas [4]. Alternatively the heat can be generated by catalytic burners which enable diesel vapor to react with oxygen via DOC catalyst mostly through surface reactions [5].

Diesel Particulate Filters (DPFs) need to be periodically regenerated in order to achieve efficient and safe vehicle operation. Under typical diesel exhaust conditions, this invariably requires the raising of the exhaust gas temperature by active means, up to the point that particulate (soot) oxidation can be self-sustained in the filter. In the present work the development path of an advanced catalytic filter technology is presented. Full scale optimized Catalytic Diesel Particulate Filters (CDPFs) are tested in the exhaust of a light-duty modern diesel engine in line with a Diesel Oxidation Catalyst (DOC). The management of the DOC-CDPF emission control system is facilitated by a virtual soot sensor in order to ensure energy-efficient operation of the emission control system.

The increasing need for controlled diesel engine emissions and the strict regulations in the abatement of diesel exhaust products lead to an ever increasing use of Diesel Particulate Filters (DPFs) in OEM applications. The periodic regeneration of DPFs (oxidation of soot particles) demands temperatures that rarely appear during engine operation. It is therefore necessary to employ direct or indirect catalytic measures. In the present work, the development and synthesis via aerosol-based routes, of nanostructured base metal oxides for direct soot oxidation, along with their characterization and their evaluation in engine exhaust is described. The synthesized powders were characterized with respect to their phase composition and morphology. XRD, SEM and TEM analysis have shown the nanostructured character of the powders, while Raman spectroscopy was employed for the preliminary characterization of the materials surface chemistry.

Catalysts that have been extensively investigated for direct soot oxidation in Catalyzed Diesel Particulate Filters (CDPFs) are very often based on mixed oxides of ceria with zirconia, materials known to assist soot oxidation by providing oxygen to the soot through an oxidation-reduction catalytic cycle. Besides the catalyst composition that significantly affects soot oxidation, other parameters such as morphological characteristics of the catalyst largely determined by the synthesis technique followed, as well as the reagents used in the synthesis may also contribute to the activity of the catalysts. In the present work, two ceria-zirconia catalyst samples with different zirconia content were subjected to different milling protocols with the aim to shift the catalyst particle size distribution to lower values. The produced catalysts were then evaluated with respect to their soot oxidation activity following established protocols from previous works.

External Exhaust Gas Recirculation (EGR) has been used on diesel engines for decades and has also been used on gasoline engines in the past. It is recently reintroduced on gasoline engines to improve fuel economy at mid and high engine load conditions, where EGR can reduce throttling losses and fuel enrichment. Fuel enrichment causes fuel penalty and high soot particulates, as well as hydrocarbon (HC) emissions, all of which are limited by emissions regulations. Under stoichiometric conditions, gasoline engines can be operated at high EGR rates (> 20%), but more than diesel engines, its intake gas including external EGR needs extreme cooling (down to ~50°C) to gain the maximum fuel economy improvement. However, external EGR and its problems at low temperatures (fouling, corrosion & condensation) are well known.

In the present work we derive analytical solutions for the problem of convection, diffusion and chemical reaction in wall-flow monoliths. The advantage of having analytical instead of numerical treatments is clear as the analytical solutions not only can be exploited to bring full scale simulations of diesel particulate filters to the real time domain, but also they enable efficient implementations on computationally limited engine control units (ECUs) for on-board management and control of emission control systems. The presentation describes the mathematical problem formulation, the governing dimensionless parameters and the corresponding assumptions. Then the analytical solution is derived and several asymptotic (for limiting values of the parameters) and approximating solutions are developed, corresponding to different physical situations. Reactant distributions in the filter are presented and discussed for several values of the parameters.

Diesel Particulate Filters (DPFs) have been successfully applied for several years to reduce Particulate Matter (PM) emissions from on-highway applications, and similar products are now also applied in off-highway markets and retrofit solutions. Most solutions are catalytically-based, necessitating minimum operating temperatures and demanding engine support strategies to reduce risks [1, 2, 3, 4, 5, 6, 7, 8]. An ignition-based thermal combustion device is applied with Cordierite and SiC filters, evaluating various DPF conditions, including effects of soot load, exhaust flow rates, catalytic coatings, and regeneration temperatures. System designs are described, including flow and temperature uniformity, as well as soot load distribution and thermal gradient response.

It is important to quantitatively characterize the automotive events in order to not only accurately interpret their past but also to reliably predict and forecast their short-term, medium-term, and even long-term future. In this paper, several automotive industry related events, i.e. vehicle safety, vehicle weight/HP ratio, the emissions of CO2, HC, CO, and NOx, are analyzed to find their general trends. Exponential and power law functions are used to empirically fit and quantitatively characterize these data with an emphasis on the two functions’ effectiveness in predictability. Finally, three empirical emission laws based on the historical HC, CO, and NOx data are proposed and the impact of these laws on emission control is discussed.

To meet the 2010 diesel engine emission regulations, an aftertreatment system was developed to reduce HC, CO, NOx and soot. In NOx reduction, a baseline SCR module was designed to include urea injector, mixing decomposition tube and SCR catalysts. However, it was found that the baseline decomposition tube had unacceptable urea mixing performance and severe deposit issues largely because of poor hardware design. The purpose of this article is to describe necessary development work to improve the baseline system to achieve desired mixing targets. To this end, an emissions Flow Lab and computational fluid dynamics were used as the main tools to evaluate urea mixing solutions. Given the complicated urea spray transport and limited packaging space, intensive efforts were taken to develop pre-injector pipe geometry, post-injector cone geometry, single mixer design modifications, and dual mixer design options.

EPA 2015 Tier IV emission requirements pose significant challenges to large diesel engine aftertreatment system (EAS) development aimed at reducing exhaust emissions such as NOx and PM. An EAS has three primary subsystems, Aftertreatment hardware, controls and fluid delivery. Fluid delivery is the subsystem which supplies urea into exhaust stream to allow SCR catalytic reaction and/or periodic DOC diesel dosing to elevate exhaust temperatures for diesel particulate filter (DPF) soot regeneration. The purpose of this paper is to discuss various aspects of fluid delivery system development from flow and pressure perspective. It starts by giving an overview of the system requirements and outlining theoretical background; then discusses overall design considerations, injector and pump selection criteria, and three main injector layouts. Steady state system performance was studied for manifold layout.