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It is well known that ethanol can be used in spark-ignition (SI) engines as a pure fuel or blended with gasoline. High enthalpy of vaporization of alcohols can affect air-fuel mixture formation prior to ignition and may form thicker liquid films around the intake valves, on the cylinder wall and piston crown. These liquid films can result in mixture non-homogeneities inside the combustion chamber and hence strongly influence the cyclic variability of early combustion stages. Starting from these considerations, the paper reports an experimental study of the initial phases of the combustion process in a single cylinder SI engine fueled with commercial gasoline and anhydrous ethanol, as well as their blend (50%vol alcohol). The engine was optically accessible and equipped with the cylinder head of a commercial power unit for two-wheel applications, with the same geometrical specifications (bore, stroke, compression ratio).

This paper reports the study of the effects of alternative diesel fuel and the impact for the air-fuel mixture preparation. The injection process characterization has been carried out in a non-evaporative high-density environment in order to measure the fuel injection rate and the spatial and temporal distribution of the fuel. The injection and vaporization processes have been characterized in an optically accessible single cylinder Common Rail diesel engine representing evaporative conditions similar to the real engine. The tests have been performed by means of a Bosch second generation common rail solenoid-driven fuel injection system with a 7-holes nozzle, flow number 440 cc/30s @100bar, 148deg cone opening angle (minisac type). Double injection strategy (pilot+main) has been implemented on the ECUs corresponding to operative running conditions of the commercial EURO 5 diesel engine.

The present study proposes the use of a MLP neural network to model the relationship between the engine crankshaft speed and parameters derived from the in-cylinder pressure cycle. This allows to have an indirect measure of cylinder pressure permitting a real time evaluation of combustion quality. The structure of the model and the training procedure is outlined in the paper. The application of the model is demonstrated on a single-cylinder engine with data from a wide range of speed and load. Results confirm that a good estimation of combustion pressure parameters can be obtained by means of a suitable processing of crankshaft speed signal.

The match among the increasing performance demands and the stringent requirements of emissions and the fuel consumption reduction needs a strong evolution in the two-wheel vehicle technology. In particular, many steps forward should be taken for the optimization of modern small motorcycles and scooters at low engine speeds and high loads. To this aim, detailed understanding of thermo-fluid dynamic phenomena that occur in the combustion chamber is fundamental. In this work, low-cost solutions are proposed to optimize ported fuel injection spark ignition (PFI SI) engines for two-wheel vehicles. The solutions are based on the change of phasing and on the splitting of the fuel injection in the intake manifold. The experimental activities were carried out in the combustion chamber of a single-cylinder 4-stroke optical engine fuelled with European commercial gasoline. The engine was equipped with a four-valve head of a commercial scooter engine.

High spatial and temporal resolution optical techniques were applied in a spark ignition (SI) engine in order to investigate the thermal and fluid dynamic phenomena occurring during the combustion process. The experiments were realized in the combustion chamber of an optically accessible single-cylinder port-fuel injection (PFI) SI engine. The engine was equipped with a four-valve head and with an external boost device. Two fuel injection strategies at closed-valve and open-valve occurring at wide open throttle were tested. Cycle-resolved digital imaging was used to follow the flame kernel growth and flame front propagation. Moreover, the effects of an abnormal combustion due to the firing of fuel deposition near the intake valves and on the piston surface were investigated. Natural emission spectroscopy in a wide wavelength range from ultraviolet to infrared was applied to detect the radical species that marked the combustion phenomena in the selected operating conditions.

The flame front propagation in normal and abnormal combustion was investigated. Cycle-resolved flame emission imaging was applied in the combustion chamber of a port fuel injection boosted spark ignition engine. The engine was fuelled with a mixture of 90% iso-octane and 10% n-heptane by volume (PRF90). The effect of fuel injection phasing was studied. The combustion process was followed from the flame kernel formation until the opening of the exhaust valves. Different phenomena correlated to the abnormal combustion were analysed. Detailed information on ignition surfaces, end-gas auto-ignitions and knock were obtained. The appearance of autoignition centres in the end gas was evaluated in terms of timing, location and frequency of occurrence.

Electronic engine controls based on non-intrusive diagnostics can significantly help in complying with the stricter and stricter regulations on pollutants emissions and fuel consumption. The aim of this paper is the use of a low-cost linear capacitive accelerometer placed on the engine block for non-intrusive diagnosis of combustion process in spark ignition engines. In particular, good correspondences between the engine block vibrations and the combustion pressure signal were obtained. The angular position of pressure peak evaluated by accelerometer data can be used in a closed-loop control system for real time control of spark advance.

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.

A satisfactory answer to the future severe normative on emissions and to the market request for spark ignition engines seems to be the use of downsized engines for passenger cars. Downsizing permits the increase in engines power and torque without the increase in cylinder capacity. The downsizing benefits are evident at part loads; on the other hand, more work should be done to optimize boosted engines at higher and full load. To this goal, a detailed knowledge of the thermo-fluid dynamic processes that occur in the combustion chamber is fundamental. The aim of this paper is the experimental investigation of the effect of the fuel injection in the intake manifold on the combustion process and pollutant formation in a boosted spark ignition (SI) engine. The experiments were performed on a partially transparent single-cylinder port fuel injection (PFI) SI engine, equipped with a four-valve head and boost device.

Four perovskite catalysts LaBO3 (B = Cr, Mn, Fe, Ni), 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, TEM, O2-TPD and CO-TPR analyses. The performance of these catalysts towards the simultaneous oxidation of soot and CO was evaluated. The 2 wt.% Au-LaNiO3 showed the best performance with a peak carbon combustion temperature of 431 °C and the half conversion of CO reached at 156 °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.

Several Li-Cr delafossite catalysts were prepared via the so-called “Solution Combustion Synthesis (SCS)” method, characterized and tested as catalysts for the combustion of diesel soot. These catalysts already showed appreciable activity at 350 °C even under loose contact conditions. An in situ SCS method was tailored to the preparation of a LiCr0.9O2 -catalyzed trap based on a SiC wall-flow monolith. Engine bench tests on these catalytic traps showed that the presence of the catalyst enabled both a more complete regeneration and a one-third fold reduction of the regeneration time compared to the case of a non-catalytic trap.

The growing demands on fuel economy and always stricter limitations on pollutant emissions has increased the interest in the ignition phenomena to guarantee successful flame development for all the spark ignition (SI) engine operating conditions. The initial size and the growth of the flame have a strong influence on the further development of the combustion process. In particular, for the new FIAT generation of turbocharged SI engines, the first times of spark ignition combustion are not yet fully understood. This is mainly due to the missing knowledge concerning the detailed physical and chemical processes taking place during the all set of the flame propagation. These processes often occur simultaneously, making difficult the interpretation of measurements. In the present paper, flame dynamic was followed by UV-visible emission imaging in an optical SI engine.

Aim of this work is to develop a general purpose model for combustion and knocking prediction in SI engines, by coupling a thermo-fluid dynamic model for engine simulation with a general detailed kinetic scheme, including the low-temperature oxidation mechanism, for the prediction of the auto-ignition behavior of hydrocarbons. A quasi-D approach is used to describe the in-cylinder thermodynamic processes, applying the conservation of mass and energy over the cylinder volume, modeled as a single open system. The complex chemistry model has been embedded into the code, by using the same integration algorithm for the conservation equations and the reacting species, and taking into account their mutual interaction in the energy balance. A flame area evolution predictive approach is used to evaluate the turbulent flame front propagation as function of the engine operating parameters.

Two different optical techniques for detection, sizing and counting nanoparticles were applied to undiluted exhaust from 16 v–1900 cc Common Rail diesel engine upstream and downstream a Catalyzed Diesel Particulate Filter (CDPF): Broadband Ultraviolet–Visible Extinction and Scattering Spectroscopy (BUVESS) and Laser Induced Incandescence (LII). They are powerful “in situ” and non-intrusive techniques; they are able to measure mass concentration and size of particles, considering their chemical properties. BUVESS overcomes the intrinsic limitations of single wavelength techniques because it takes advantage of data at several wavelengths to retrieve primary particle size distribution. LII measures mean size of primary particles with a large dynamic range, not limited by aggregate size and by complex retrieving procedure.

Nano-structured bulk Li-substituted La-Cr perovskites were prepared, characterized, tested in comparison with the reference LaCrO3. The progressive increase in the Li content of the catalysts induces an increase in the catalytic activity owing to the enhancement of the amount of weakly chemisorbed oxygen O-species, key players in the soot oxidation mechanism. However, beyond 20% Cr substitution with Li, part of this latter metal was segregated as LiCrO2. The best single-phase catalyst (La0.8Cr0.8Li0.2O3) was already active well below 350°C. Catalytic traps were prepared by in situ combustion synthesis within cordierite and SiC wall-flow filters on the basis of the above catalysts and tested on real diesel exhaust gases in an engine bench, fully confirming the encouraging results obtained on powder catalysts.

The paper describes the results of a parallel 1D thermo-fluid dynamic simulation and experimental investigation of a DI turbocharged Diesel engine. The attention has been focused on the overall engine performances (air flow, torque, power, fuel consumption) as well as on the emissions (NO and particulate) along the after-treatment system, which presents a particulate filter. The 1D research code GASDYN for the simulation of the whole engine system has been enhanced by the introduction of a multi-zone quasi-dimensional combustion model for direct injection Diesel engines. The effect of multiple injections is taken into account (pilot and main injection). The prediction of NO and soot has been carried out respectively by means of a super-extended Zeldovich mechanism and by the Hiroyasu kinetic approach.

The DEXA Cluster consisted of three closely interlinked projects. In 2003 the DEXA Cluster concluded by demonstrating the successful development of critical technologies for Diesel exhaust particulate after-treatment, without adverse effects on NOx emissions and maintaining the fuel economy advantages of the Diesel engine well beyond the EURO IV (2000) emission standards horizon. In the present paper the most important results of the DEXA Cluster projects in the demonstration of advanced particulate control technologies, the development of a simulation toolkit for the design of diesel exhaust after-treatment systems and the development of novel particulate characterization methodologies, are presented. The motivation for the DEXA Cluster research was to increase the market competitiveness of diesel engine powertrains for passenger cars worldwide, and to accelerate the adoption of particulate control technology.

Multidimensional simulation of the soot formation process in a diesel engine is realised exploiting quantitative measurements of the soot volume fraction and diameter obtained by optical techniques. Broadband extinction and scattering measurements are performed on an optically accessible 4-stroke engine where a forced air motion allows a strong prevalence of the premixed stage of combustion with respect to the non-premixed one. Two semi-empirical models for soot formation are tested in the numerical simulation, which is performed using a customized version of the KIVA-3 code. The need of furnishing coherent values of the soot particles density and mean diameter to the one of the two models requiring this kind of information, is highlighted and demonstrated to be crucial in avoiding over-prediction of the soot concentration.

Polychromatic extinction and chemiluminescence techniques, from ultraviolet to visible, were applied in an optical diesel engine, in order to analyze the temporal and spatial evolution of a high pressure fuel jet interacting with a swirling air motion. A fully flexible Common Rail fuel injection system equipped with a single hole nozzle was used. The experiments were performed at fixed engine speed and air/fuel ratio for three injection strategies. The first one consisted of a main injection to compare with those operating at low pressure injection. The other ones were based on a pilot and main injections, typical of current direct injection diesel engines, with different dwell time. A detailed investigation of the mixture formation process inside the combustion chamber during the ignition delay time was performed. The liquid and vapor fuel distribution in the combustion chamber was obtained analyzing the polychromatic extinction spectra.

Conventional methods to measure gas concentrations and, in particular, NO are typically based on sampling by valve, sample treatment and subsequent analysis. These methods suffer low spatial and temporal resolution. The introduction of high energy lasers in combination with fast detection systems allowed to detect the NO distribution inside optically accessible Diesel engines. In this paper, a high spatial and temporal resolution in-situ technique based on ultraviolet - visible absorption spectroscopy is proposed. The characterization of the combustion process by the detection of gaseous compounds from the start of combustion until the exhaust phase was performed. In particular, this technique allows the simultaneous detection of NO and OH absolute concentrations inside an optically accessible Diesel combustion chamber.