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The use of catalyzed diesel particulate filter (CDPF) systems in light duty diesel (LDD) vehicles is becoming increasingly common. The primary functions of the system are to remove carbon monoxide (CO) and hydrocarbons (HC) from the vehicle exhaust stream, while simultaneously reducing the level of particulate matter (PM) emissions to ambient background levels. These systems can comprise either a separate diesel oxidation catalyst (DOC) and a downstream CDPF, or a single unit CDPF with the DOC functions incorporated within the CDPF. The single CDPF unit provides higher regeneration efficiency as it is located nearer to the engine and also cost benefits, as only a single unit is required compared to the alternative separate DOC and CDPF arrangement. A model describing the performance of the single unit CDPF for emissions control has been developed, with particular emphasis on achieving predictions of the CO and HC emissions over transient vehicle drive cycles.

Empirical models for engine-out oxides of Nitrogen (NOx) and smoke emissions have been developed for the purpose of minimizing transient emissions while maintaining transient response. Three major issues have been addressed: data acquisition, data processing and modeling method. Real and virtual transient parameters have been identified for acquisition. Accounting for the phase shift between transient engine events and transient emission measurements has been shown to be very important to the quality of model predictions. Several methods have been employed to account for the transient transport delays and sensor lags which constitute the phase shift. Finally several different empirical modeling methods have been used to determine the most suitable modeling method for transient emissions. These modeling methods include several kinds of neural networks, global regression and localized regression.

A prototype 2007 ISL Cummins diesel engine equipped with a diesel oxidation catalyst (DOC), diesel particle filter (DPF), variable geometry turbocharger (VGT), and cooled exhaust gas recirculation (EGR) was tested at Southwest Research Institute (SwRI) under a high-load accelerated durability cycle for 1000 hours with B20 soy-based biodiesel blends and ultra-low sulfur diesel (ULSD) fuel to determine the impact of B20 on engine durability, performance, emissions, and fuel consumption. At the completion of the 1000-hour test, a thorough engine teardown evaluation of the overhead, power transfer, cylinder, cooling, lube, air handling, gaskets, aftertreatment, and fuel system parts was performed. The engine operated successfully with no biodiesel-related failures. Results indicate that engine performance was essentially the same when tested at 125 and 1000 hours of accumulated durability operation.

The definition of the energy management strategy for a hybrid electric vehicle is a key element to ensure maximum energy efficiency. The ability to optimally manage the on-board energy sources, i.e., fuel and electricity, greatly affects the final energy consumption of hybrid powertrains. In the case of plug-in series-hybrid architectures, such as Range-Extender Electric Vehicles (REEVs), fuel efficiency optimization alone can result in a stressful operation of the range-extender engine with an excessively high number of start/stops. Nonetheless, reducing the number of start/stops can lead to long periods in which the engine is off, resulting in the after-treatment system temperature to drop and higher emissions to be produced at the next engine start.

For better fuel economy and reduced emissions; fuel system plays a very important role. There are some major challenges related to development of suitable fuel system due to high static (~2000 bar) and fluctuating pressures in high pressure (HP) fuel lines. This enforces to design leak proof joints as they directly affect engine operation and can cause customer inconvenience. It is also critical from safety standpoint. Sealing capability of a joint is generally evaluated by sealing pressure, length of the sealing width and retaining capability of joint preload over time. Theoretically, it is known that preload loss at a joint is a combination of several factors such as; thread pitch, nut stiffness and friction at threads. In our current work the cause of leakage in HP fuel line joints is explored. Using fish bone diagram for RCA (Root Cause Analysis), probable causes are narrowed down and design parameters responsible for preload loss are identified.

Valve seat inserts (VSI) are installed in cylinder heads to provide a seating surface for poppet valves. Insert material is more heat and wear resistant than the base cylinder head material and hence it makes them better suited for valve seating and improved engine durability. Also use of inserts permits easier repair or rebuild of cylinder heads as only the wear surfaces need to be replaced. Desirable performance characteristics are appropriate sealing, heat-transfer and minimizing valve’s seating face to VSI wear and undesired outputs include valve seat dropping and cracking. With the downsizing trend of diesel engines, it leads to increasing power density and therefore higher cylinder pressure and temperatures. Hence the engine components are getting exposed to more severe loadings and hence to damage modes, which were heretofore not experienced. Among such possible damage modes are insert’s yielding and corresponding press-fit loss leading to either it’s cracking or drop-out.

This paper describes steady state, computationally rigorous, three-dimensional conjugate heat transfer 3D CFD analysis of an oil cooler. Thermal performance of an oil cooler is very significant from engine oil consumption, bearings performance etc. In an engine water jacket, coolant flows around and through the oil cooler making the flow three dimensional. Therefore, demanding the need of a 3D CFD analysis for capturing all the flow and heat transfer aspects and thereby accurate prediction of thermal performance. An oil cooler contains intricate turbulators in flow paths and have dimensions varying from as small as 0.25 mm to as large as 350 mm, therefore making the meshing and solution a formidable task. In current work an oil cooler with all the intricate details is modelled in a commercial CFD code. Objective is to develop a solution approach which can predict thermal performance of an oil cooler in an accurate way.

One field-returned DPF loaded with a high amount of ash is examined using experimental and modeling approaches. The ash-related design factors are collected by coupling the inspection results from terahertz spectroscopy with a calibrated DPF model. The obtained ash packing density, ash layer permeability and ash distribution profile are then used in the simulation to assess the ash impact on DPF backpressure and regeneration behaviors. The following features have been observed during the simulation: 1 The ash packing density, ash layer permeability and ash distribution profile should be collected at the same time to ensure the accurate prediction of ash impact on DPF backpressure. Missing one ash property could mislead the measurement of the other two parameters and thus affects the DPF backpressure estimation. 2 The ash buildup would gradually increase the frequency for the backpressure-based active soot regeneration.

Gasoline direct injection (GDI) engines have become very attractive in transportation due to several benefits over preceding engine technologies. However, GDI engines are associated with higher levels of particulate matter (PM) emissions, which is a major concern for human health. The aim of this work is to broaden the understanding of the effect of hydrogen combustion and the influence of the three way catalytic converter (TWC) on PM emission characteristics. The presence of hydrogen in GDI engines has been reported to reduce fuel consumption and improve the combustion process, making it possible to induce higher rates of EGR. A prototype exhaust fuel reformer build for on-board vehicle hydrogen-rich gas (reformate) production has been integrated within the engine operation and studied in this work.

To investigate free floating piston pin behavior in a heavy duty diesel engine, an unused piston-pin-rod joint was instrumented. Combining telemetry systems with inductively powered transducers, piston pin subsurface temperature and pin rotation with respect to the piston were measured over a 30 minute steady state engine test.

In this work, an alternative method is proposed and validated for quantifying the axial performance of a state-of-the-art Cu zeolite SCR catalyst. Catalyst cores of a standard length, with varying lengths of wash-coated regions were used to axially resolve the functional performance of the SCR catalyst. This proposed method was validated by quantifying the catalyst entrance and exit effects, as well as the effect of non-uniform wash-coat loading densities. This method is less susceptible to some of the complications highlighted in the previous studies, such as flow uniformity between channels, as well as radiative heating effects, since the product gases are sampled across the entire monolith cross-section rather than through a single catalyst channel. The specific catalyst functions quantified include: NO and NH₃ oxidation, NH₃ storage capacity, as well as NOx conversion efficiency.

In this study we investigated the interaction of short- and long-chain hydrocarbons (HCs), represented by propene (C₃H₆) and n-dodecane (n-C₁₂H₂₆), respectively, with a state-of-the-art small-pore Cu-Zeolite SCR catalyst. By varying HC adsorption conditions, we determined that physisorption was the primary mechanism for some minor HC storage at low temperatures (≺ 200°C), while chemical transformation was involved in more substantial HC storage at higher temperatures (200-400°C). The latter was evidenced by the oxygen-dependent and thermally activated nature of the storage process, and further confirmed by the carbon-rich composition of the deposits. The nature of HC-derived deposits of different origins and amounts was further probed using the standard SCR reaction at kinetically challenging conditions (at 200°C), as well by ammonia adsorption/desorption experiments.

The use of vanadia selective catalytic reduction (V-SCR) catalysts for NOX reduction from diesel engine exhaust is well known. These catalysts are also active for hydrocarbon (HC) and particulate matter (PM) oxidation. This dual functionality (oxidation and reduction) of V-SCR catalysts can help certain applications achieve the legislative limits with an improved margin. In this work, NOX reduction, HC and CO oxidation over V-SCR were studied independently and simultaneously in microreactor tests. The effect of various parameters (HC speciation, concentration, ANR, and NO₂/NOX ratio) was investigated and the data was used to develop a kinetic model. Oxidation of CO, C₃H₆, and n-C₁₀H₂₂ is first order in CO/HC, while C₇H₈ oxidation is less than first order in C₇H₈. All these reactions were zero order in O₂. Oxidation activity decreased in order: C₇H₈ ≻ n-C₁₀H₂₂ ≻ C₃H₆ ≻ CO. HC oxidation was inhibited by NH₃.

Mitigation of ammonia slip from SCR system is critical to meeting the evolving NH₃ emission standards, while achieving maximum NOx conversion efficiency. Ammonia slip catalysts (ASC) are expected to balance high activity, required to oxidize ammonia across a broad range of operating conditions, with high selectivity of converting NH₃ to N₂, thus avoiding such undesirable byproducts as NOx or N₂O. In this work, new insights into the behavior of an advanced ammonia slip catalyst have been developed by using accelerated progressive catalyst aging as a tool for catalyst property interrogation. The overall behavior was deconstructed to several underlying functions, and referenced to an active but non-selective NH₃ oxidation function of a diesel oxidation catalyst (DOC) and to the highly selective but minimally active NH₃ oxidation function of an SCR catalyst.

A one-dimensional model of a NOx trap system was developed to describe NOx storage during the lean operation, and NOx release and subsequent reduction during the rich regeneration process. The development of a NOx trap model potentially enables the optimisation of catalyst volume, precious metal loading, substrate type and regeneration strategy for these complex systems. To develop a fundamental description of catalytic activity, experiments were conducted to investigate the key processes involved in isolation (as far as possible), using a Pt/Rh/BaO/Al2O3 model catalyst. A description of the storage capacity as a function of temperature was determined using NOx breakthrough curves and the storage portion of more dynamic lean-rich cycling experiments. NOx breakthrough curves were also used for determination of rate of NOx storage. Kinetics for NOx reduction, as well as CO and HC oxidation, were determined using steady state reactor experiments.

For renewable fuels to displace petroleum, they must be compatible with emissions control devices. Pure biodiesel contains up to 5 ppm Na + K and 5 ppm Ca + Mg metals, which have the potential to degrade diesel emissions control systems. This study aims to address these concerns, identify deactivation mechanisms, and determine if a lower limit is needed. Accelerated aging of a production exhaust system was conducted on an engine test stand over 1001 h using 20% biodiesel blended into ultra-low sulfur diesel (B20) doped with 14 ppm Na. This Na level is equivalent to exposure to Na at the uppermost expected B100 value in a B20 blend for the system full-useful life. During the study, NOx emissions exceeded the engine certification limit of 0.33 g/bhp-hr before the 435,000-mile requirement.

A simple 1-dimensional filter model, with symmetric and asymmetric channels, has been developed to investigate the fundamental behavior and performance of ceramic partial diesel particulate filters (PFs). The governing equations of mass and momentum are similar to those of a full DPF [7, 15]. A standard DPF with the plugs at its inlet face removed has been referred to as a ‘rear-plugged PF’ while, one with the plugs at the outlet face removed has been referred to as a ‘front-plugged PF’ in the present study. Removal of some of the plugs from a standard ceramic DPF reduces the (i) overall pressure drop (ΔP) across the filter, (ii) filtration efficiency (FE) of the DPF, and (iii) manufacturing cost. Partial filters stand a high chance of being deployed in diesel exhaust after-treatment systems for the emerging markets (Brazil, Russia, India, China) that follow Euro 4 emission regulations.

Two approaches were adopted to study soot oxidation by NO₂; firstly microreactor tests were performed on soot produced by a soot generator over a range of NO₂ concentrations and temperatures. This enabled measurement to be made under well-controlled conditions. Secondly, soot oxidation measurements were made on an engine bench to obtain data under more realistic, if less controlled, conditions. In the microreactor work NO₂ consumption by soot oxidation and the selectivity of the soot oxidation to CO and CO₂ were measured. The latter was found to vary only slightly with temperature and to be independent of NO₂ concentration. By modeling this data using a 1-dimensional model, rate equations for the soot-NO₂ reaction were determined. These were then tested against the engine data. The soot used in this study was characterized by thermogravimetric analysis, N₂ physisorption and transmission electron microscopy.

In this contribution, nuanced changes of a commercial Cu-SSZ-13 catalyst with hydrothermal aging, which have not been previously reported, as well as their corresponding impact on SCR functions, are described. In particular, a sample of Cu-SSZ-13 was progressively aged between 550 to 900°C and the changes of performance in NH3 storage, oxidation functionality and NOx conversion of the catalyst were measured after hydrothermal exposure at each temperature. The catalysts thus aged were further characterized by NH3-TPD, XRD and DRIFTS techniques for structural changes. Based on the corresponding performance and structural characteristics, three different regimes of hydrothermal aging were identified, and tentatively as assigned to “mild”, “severe” and “extreme” aging. Progressive hydrothermal aging up to 750°C decreased NOx conversion to a small degree, as well as NH3 storage and oxidation functions.

In this work fuel dilution of engine oil, and the impact of biodiesel fuel on dilution, were examined. New emissions requirements have driven the adoption of a range of aftertreatment systems for diesel engines. These aftertreatment devices in many cases have specific requirements for exhaust composition and temperature. Meeting these requirements can lead to fuel dilution of the engine oil. Measurement of fuel dilution of engine oil can be challenging, and in this study a new strategy for utilizing Fourier Transform Infrared Spectroscopy (FTIR) was examined. A synthetic component of aviation oil, pentaerythritol ester (PE), was found to be a very useful tracer for measuring dilution with ultra low sulfur diesel (ULSD), but not useful for measuring dilution with B20. Fuel dilution and evaporation rates were measured for both ULSD and for a blend of biodiesel and ULSD (B20).