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Two different modifications of the baseline cylinder head configuration have been designed and experimentally tested on a MultiAir turbocharged gasoline engine, in order to address the issue of the poor in-cylinder turbulence levels which are typical of the Early-Intake-Valve-Closing (EIVC) strategies which are adopted in Variable Valve Actuation systems at part load to reduce pumping losses. The first layout promotes turbulence by increasing the tumble motion at low valve lifts, while the second one allows the addition of a swirl vortex to the main tumble structure. The aim for both designs was to achieve a proper flame propagation speed at both part and full load. The experimental activity was initially focused on the part load analysis under high dilution of the mixture with internal EGR, which can allow significant further reductions in terms of pumping losses but, on the other hand, tends to adversely affect combustion stability and to increase cycle-to-cycle variations.

The effects of using blended renewable diesel fuel (30% vol.), obtained from Rapeseed Methyl Ester (RME) and Hydrotreated Vegetable Oil (HVO), in a Euro 5 small displacement passenger car diesel engine have been evaluated in this paper. The hydraulic behavior of the common rail injection system was verified in terms of injected volume and injection rate with both RME and HVO blends fuelling in comparison with commercial diesel. Further, the spray obtained with RME B30 was analyzed and compared with diesel in terms of global shape and penetration, to investigate the potential differences in the air-fuel mixing process. Then, the impact of a biofuel blend usage on engine performance at full load was first analyzed, adopting the same reference calibration for all the tested fuels.

A 2007 Cummins ISL 8.9L direct-injection common rail diesel engine rated at 272 kW (365 hp) was used to load the filter to 2.2 g/L and passively oxidize particulate matter (PM) within a 2007 OEM aftertreatment system consisting of a diesel oxidation catalyst (DOC) and catalyzed particulate filter (CPF). Having a better understanding of the passive NO2 oxidation kinetics of PM within the CPF allows for reducing the frequency of active regenerations (hydrocarbon injection) and the associated fuel penalties. Being able to model the passive oxidation of accumulated PM in the CPF is critical to creating accurate state estimation strategies. The MTU 1-D CPF model will be used to simulate data collected from this study to examine differences in the PM oxidation kinetics when soy methyl ester (SME) biodiesel is used as the source of fuel for the engine.

A quasi-dimensional multizone combustion model, that was previously developed by the authors, has been refined and applied for the analysis of combustion and emission formation in a EURO V diesel engine equipped with a piezo indirect-acting injection system. The model is based on the integration of the predictive non-stationary variable-profile 1D spray model recently presented by Musculus and Kattke, with a diagnostic multizone thermodynamic model specifically developed by the authors. The multizone approach has been developed starting from the Dec conceptual scheme, and is based on the identification of several homogeneous zones in the combustion chamber, to which mass and energy conservation laws have been applied: an unburned gas zone, made up of air, EGR (Exhaust Gas Recirculation) and residual gas, several fuel/unburned gas mixture zones, premixed combustion burned gas zones and diffusive combustion burned gas zones.

The present work has the aim of developing a fast approach for the predictive calculation of in-cylinder combustion temperatures and NOx formation in diesel engines, under steady state and transient conditions. The model has been tested on a PC, and found to require very little computational time, thus suggesting it could be implemented in the ECU (Engine Control Unit) of engines for model-based control tasks. The method starts with the low-throughput predictive combustion model that was previously developed by the authors, which allows the predictive estimation of the heat-release rate and of the in-cylinder pressure trace to be made on the basis of the injection parameters and of a few quantities measured by the ECU, such as the intake manifold pressure and temperature.

The aim of this work was to obtain a reduction in pollutant emissions, in particular for NOx and Soot, in an “Off-Road” DI Diesel Engine, equipped with a common rail injection system, by means of exhaust gas recirculation (EGR). First, an engine simulation was performed using a one-dimensional code, and the model was then calibrated with experimental results obtained from a previous research work conducted on bench tests. Thanks to the engine model, specific emissions were then determined in all conditions, that is, in “eight modes” pertaining to engine loads and speeds. Both the injection advance and EGR amount were changed for all of these conditions in order to obtain the best compromise between fuel consumption and emissions and to respect standard regulations. The investigation was performed using both the Wiebe and a more complex combustion models; this latter allows in fact to determine the soot emission through the Nagle-Strickland model.

Molybdenum sulfide nanoparticles have been successfully obtained, for lubricant applications, by means of a wet chemical synthesis in an aqueous solution employing ammonium molybdate, citric acid and ammonium sulfide as the reactants. Some molybdenum-citrate complexes were formed and they reacted with the ammonium sulfide to form MoS₂ nanoparticles. Mo:citrate molar ratio was identified as being the most relevant of the synthesis parameters that affected the phase and morphology of the final products. The optimized nanopowders were softly agglomerated and amorphous, with a mean size of the primary particles of about 30 nm. The compatibility between the thus obtained MoS₂ nanopowders and some commercial after-treatment catalysts for diesel vehicle engines was tested. Diesel oxidation, soot combustion and ammonia-SCR de-NOx catalysts were considered as were the possible effects on the catalytic activity and their possible reaction to the MoS₂ additive.

A new procedure for the real-time estimation of the EGR rate and charge oxygen concentration has been developed, assessed and applied to a low-compression ratio GMPT-E EURO V diesel engine. High EGR rates are usually employed in modern diesel engines to reduce combustion temperatures and NOx emissions, especially at medium-low load and speed conditions. The EGR rate is usually calibrated in steady-state conditions, but, under transient conditions, it can be responsible for misfire occurrence or non optimal combustion cycles, if not properly controlled. In other words, combustion instabilities can occur, especially during tip-in maneuvers, which imply transition from high EGR (low load) to low EGR (high load) rates. Misfire is determined by a temporary reduction in the intake charge oxygen concentration during the closure of the EGR valve.

An innovative approach to the study of combustion and emission formation in modern diesel engines has been applied to a EURO V diesel engine equipped with an indirect-acting piezo injection system. The model is based on the joint use of a predictive non-stationary 1D spray model, which has recently been presented by Musculus and Kattke, and a diagnostic multizone thermodynamic model developed by the authors. The combustion chamber content has been split into homogeneous zones, to which mass and energy conservation laws have been applied: an unburned gas zone, made up of air, EGR and residual gas, several fuel/unburned gas mixture zones, premixed combustion burned gas zones and diffusive combustion burned gas zones. The 1D spray model enables the mixing process dynamics of the different fuel parcels with the unburned gas to be estimated for each injection pulse; therefore, the equivalent ratio time-history of each mixture zone can be estimated.

In this work different internal and external EGR strategies, combined with extreme Miller cycles, were analyzed by means of a one-dimensional CFD simulation code for a Wärtsilä 6-cylinder, 4-strokes, medium-speed marine diesel engine, to evaluate their potential in order to reach the IMO Tier 3 NOx emissions target. By means of extreme Miller cycles, with Early Intake Valve Closures (up to 100 crank angle degrees before BDC), a shorter compression stroke and lower charge temperatures inside the cylinder can be achieved and thanks to the cooler combustion process, the NOx-specific emissions can be effectively reduced. EIVC strategies can also be combined with reductions of the scavenging period (valve overlap) to increase the amount of exhaust gases in the combustion chamber. However, the remarkably high boost pressure levels needed for such extreme Miller cycles, require mandatorily the use of two-stage turbocharging systems.

As in the standard American Society for Testing and Materials (ASTM) procedure which is used to evaluate the fuel Octane Number (ON), some signal properties are considered, while others are neglected, it happens that different pressure signals of the sensor, obtained from different fuels and operating conditions, can lead to the same Knock Intensity index (KI) value, even though the knock behavior is not the same. Therefore the aim of this work was to analyze the standard signal processing chain of the Cooperative Fuel Research engine (CFR) (from the pressure sensor to the knock-meter display) and its effects on the value of the KI, for different fuels and operating conditions.

In diesel engines the optimization of engine-out emissions, combustion noise and fuel consumption requires the experimental investigation of the effects of different injection strategies as well as of a large number of engine operating variables, such as scheduling of pilot and after pulses, rail pressure, EGR rate and swirl level. Due to the high number of testing conditions involved full factorial approaches are not viable, whereas Design of Experiment techniques have demonstrated to be a valid methodology. However, the results obtained with such techniques require a subsequent critical analysis, so as to investigate the cause and effect relationships between the set of engine operating variables and the combustion process characteristics that affect pollutant formation, noise of combustion and engine efficiency.

Different hybrid powertrains for a European mid-size passenger car were evaluated in this paper through numerical simulation. Different degrees of hybridizations, from micro to mild hybrids, and different architectures and power sources management strategies were taken into account, in order to obtain a preliminary assessment of the potentialities of different hybrid systems for the European passenger car market. Both diesel and gasoline internal combustion engines were considered: a 1.6 dm₃ Common Rail turbocharged diesel, and a 1.4 dm₃ spark ignition turbocharged engine, equipped with an innovative Variable Valve Actuation system. Diesel hybrid powertrains, although being subject to NOx emissions constraints that could jeopardize their benefits, offered substantial advantages in comparison with gasoline hybrid powertrains. Potentialities for fuel consumption reductions up to 25% over the NEDC were highlighted, approaching the 2020 EU 95 g/km CO₂ target.

Different EGR system layouts (a Long Route, a Short Route, and a combination of the two) were evaluated by means of both numerical simulation and experimental tests. In particular, a one-dimensional fluid-dynamic engine model was built in order to evaluate the potential of a Long Route EGR system as well as the potential of different EGR combinations between Long and Short Route. By means of the one-dimensional model, used as a virtual test bench, the estimations of the NOx emissions, based on the Extended Zeldovich Mechanism (EZM), for the different solutions, were compared and valuable information for the calibration of the coordinated EGR LR, EGR SR and Variable Geometry Turbine (VGT) control systems was obtained.

La1-xAxNi1-yByO3 nanostructured perovskite-type oxides catalysts (where A = Na, K, Rb and B = Cu; x = 0, 0.2 and y = 0, 0.05, 0.1), also supporting 2% in weight of gold, were prepared via the so-called “Solution Combustion Synthesis (SCS)” method, and characterized by means of XRD, BET, FESEM-EDS and TEM analyses. The performance of these catalysts evaluated. The 2 wt.% Au-La0.8K0.2Ni0.9Cu0.1O3 showed the best performance with a peak carbon combustion temperature of 367°C and the half conversion of CO reached at 141°C. The same nanostructured catalyst, deposited by in situ SCS directly over a SiC filter and tested on real diesel exhaust gases, fully confirmed the encouraging results obtained on the powder catalyst.

La1-xAxNi1-yByO3 nanostructured perovskite-type oxides catalysts (where A = Na, K, Rb and B = Cu; x = 0, 0.2 and y = 0, 0.05, 0.1), also supporting 2% in weight of gold, were prepared via the so-called “Solution Combustion Synthesis (SCS)” method, and characterized by means of XRD, BET, FESEM-EDS and TEM analyses. The performance of these catalysts towards the simultaneous oxidation of soot and CO was evaluated. The 2 wt.% Au-La0.8K0.2Ni0.9Cu0.1O3 showed the best performance with a peak carbon combustion temperature of 367 °C and the half conversion of CO reached at 141 °C. The same nanostructured catalyst, deposited by in situ SCS directly over a SiC filter and tested on real diesel exhaust gases, fully confirmed the encouraging results obtained on the powder catalyst.

In this study, a new EGR control technique, based on the estimate of the oxygen concentration in the intake manifold, was firstly investigated through numerical simulation and then experimentally tested, both under steady state and transient conditions. The robustness of the new control technique was also tested and compared with that of the conventional EGR control technique by means of both numerical simulation and experimental tests. Substantial reductions of the NOx emissions under transient operating conditions were achieved, and useful knowledge for controlling the EGR flow rate more accurately was obtained.

Diesel engines continue to be widely used in heavy-duty commercial applications around the world, and they are also gaining popularity in light-duty applications such as passenger cars. With this comes increased concern for and regulation of diesel emissions - most notably particulate matter (PM) and nitric oxide (NOx) emissions. As the restrictions grow tighter, exhaust aftertreatment technologies must become more efficient and reliable. The 55 SAE technical papers in this compilation will guide engineers in their efforts to meet these new regulations, by summarizing the latest diesel exhaust aftertreatment technology for both light- and heavy-duty applications.

Nano-structured perovskite-type oxides catalysts La1-xAxFe1-yByO3 (where A = Na, K, Rb and B = Cu), prepared by the Solution Combustion Synthesis (SCS) method and characterized by BET, XRD, FESEM, AAS and catalytic activity tests in microreactors and engine bench, proved to be effective in the simultaneous removal of soot and NO, the two prevalent pollutants in diesel exhaust gases in the temperature range 350-450°C. The best compromise between soot and nitrogen oxide abatement was shown by La-K-Cu-FeO3 catalyst which displayed the highest catalytic activity towards carbon combustion and the highest NO conversion activity.

Although the use of Exhaust Gas Recirculation (EGR) is nowadays mandatory for automotive diesel engines to achieve NOx emissions levels complying with more and more stringent legislation requirements, electronically controlled EGR systems still represent an expensive technology, often unsuitable for small diesel engines for off-road applications or for two/three wheelers. An interesting option for these categories of small diesel engines is the so-called “internal EGR”, which is obtained by modifying the intake or the exhaust valve lift profile, in order to increase the fraction of exhaust residuals at the end of the intake stroke. Different valve lift profiles were therefore evaluated for a 2 cylinders, 700 cc, Lombardini IDI diesel engine, equipping a light 4 wheelers vehicle.