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The pressure losses across the different parts of a regenerative Diesel Particulate Filter (DPF) have been modeled and compared with the measured pressure loss and with the measured changes in the instantaneous weight of the DPF of a commercial automotive diesel engine. The comparisons were made in three operating conditions selected among those included in the transient cycle established in the European Emission Directive. The first one is a low-load mode, with high soot emissions and therefore with high contribution to the DPF charge. The second one is a medium-load mode, in which the balance of soot charge versus spontaneous soot regeneration leads to a slow DPF charging, the temperature at the exhaust manifold being high enough to permit active regeneration. The third one is a high-load mode, in which the spontaneous regeneration leads to a net DPF discharge, the active regeneration becoming useless.

The effect of the biodiesel feedstock on the engine performance and emissions is expected to become increasingly important as the emissions regulations become more stringent (Euro 5). This work aims to study the effect of the degree of unsaturation of a biodiesel fuel (which is a characteristic of the original oil), this being quantified by the iodine number, on the pollutant emissions and combustion timing. Four biodiesel fuels with iodine numbers ranging from 90 to 125 were tested pure and blended (30% and 70% biodiesel content, volume basis) with a diesel reference fuel, which was tested too, in a four-cylinder, 2.2 litre, turbocharged, direct injection diesel engine. The operation modes were selected to be representative of the New European Driving Cycle. In general, pure biodiesel fuels, compared to the reference fuel, resulted in sharp reductions in particle mass and opacity (60-70%) and in a slight increase in both fuel consumption (around 15% in mass) and NOx emissions (9%).

Methyl esters obtained from the most interesting Spanish oleaginous crops for energy use -sunflower and cynara cardunculus- were both used as diesel fuels in this work, pure and in 25% blends with a reference commercial fuel which was also used pure. A stationary engine test bed, together with the appropriate instrumentation for chemical and morphological analysis, allowed to evaluate the effect of these fuels on the engine emissions, particularly in the main particulate matter characteristics, such as soluble organic fraction, origin of adsorbed hydrocarbons, sulphate content, particle number per unit filter surface, and mean particle diameter. Both the consideration of the main thermochemical properties of the tested fuels and the computations of a chemical equilibrium model were helpful for the analysis of the experimental results.

A study about the utilisation of producer gas from gasifiers for obtaining mechanical energy in a SI engine is presented in this work. Therefore, the influence of the gas composition and its thermodynamic properties on the combustion characteristics and on the engine performance are analysed. A home-made chemical equilibrium model which considers 28 chemical species was used to calculate the gas composition as a function of the gasification conditions, and to study the influence of the gas composition on some thermochemical parameters such as adiabatic flame temperature and heat release. The chemical kinetic package CHEMKIN III was also used to study its autoignition behaviour. Finally, a quasi-dimensional two-zone model for SI engines was used to calculate the knock tendency and to analyse the effect of fuel composition on some combustion parameters related to engine performance (IMEP, cylinder pressure, etc.).

A nonequilibrium approach for the instantaneous calculation of the composition of 29 chemical species is used in this work to simulate the evolution of the gas composition in a Diesel engine cylinder from the start of combustion to the exhaust opening. A discretization of the heat release law is used as a sequential source of combustion products, which are then subjected the evolution of pressure directly measured from the cylinder engine, and to the evolution of a burnt-zone temperature obtained from the same pressure signal through a diagnosis thermodynamic model. For each burning fuel package, the equilibrium composition and the corresponding adiabatic flame temperature are considered as initial conditions for the kinetic calculation of the gas composition evolution.

The particulate reduction targets imposed by regulations require wide knowledge about the effect of fuel formulation on both particulate emissions and composition. The results of a set of engine steady test-bed experiments, extraction procedures and chemical analysis are presented in this paper, aiming to study the effect of some of the main fuel properties on the particulate emissions and composition of a typical European passenger car Diesel engine. The tested fuels had different properties (density, volatility, cetane number, aromatic content, sulphur content, etc.), and also different engine operating conditions such as torque and engine speed, were tested.

Different extraction techniques have been analyzed when applied to the extraction of the soluble organic fraction from diesel particulate matter (DPM). It has been proved that a complete extraction (not frequently reached under conditions usually adopted in literature) is needed if a good characterization of both soluble and insoluble organic fraction is to be attained. Ultrasonication and microwave methods with mixtures of dichloromethane and benzene used as solvent lead to maximum extraction efficiency under two different conditions. Supercritical extraction with CO2 was also performed during 20 minutes in static state and 20 minutes in dynamic state, with similar results to these techniques. However, soxhlet extraction reaches higher efficiency, but only if the number of cycles and the solvent composition are carefully chosen. An incomplete extraction leads to misinterpretation of the SOF origin, since the oil contribution is not satisfactory considered.

With the objective of optimising the measurement procedure, the influence of different operating parameters of a certification-like dilution mini-tunnel, such as the dilution ratio and the filtering temperature, is firstly presented in this paper. By means of an environmental chamber, both blank and charged filters were subjected to a range of different temperature and humidity conditions, as well as to different conditioning time periods. In all cases the weighted filters from the mentioned tests were subjected to a soxhlet extraction method, which permitted the chemical analysis of both the soluble organic fraction by gas chromatography and mass spectrometry, and the insoluble one by high performance liquid chromatography (HPLC) and infrared spectrography. Also the contribution of fuel and lubricant to the particulate matter was determined. All this information was related to the mini-tunnel operating parameters and to the ambient conditions.

The results from the experimental diagnosis of the combustion process taking place in a 0.5 litre single cylinder D.I. Diesel engine with common rail injection system are presented and analysed in this paper. Some parameters characterising the injection process were modified during the experimental study, such as the start of injection, the pressure in the common rail and the injection hole diameter. Fuel delivery was kept constant in all cases. The tests were scheduled with two objectives: to determine the separate effect of each of the mentioned parameters, and to analyse the effect of the spray characteristics, for which injection pressure and hole diameter values were combined to provide similar injection rate and injection duration. The combustion diagnosis was carried out using a thermodynamic model based on the instantaneous thermodynamic properties of the gas in the chamber, which are affected in the model by the injection law input.

An experimental study has been made on a small size single cylinder supercharged DI Diesel engine, with adequate equipment for its measurement, control, and diagnostics, in order to analyse the effect of exhaust gas recirculation on engine emissions, at partial loads. Along-side this work, an existing combustion model, of phenomenological type, has been adapted to consider the effect of the presence of burnt products among the reactives of the chemical reaction. The joint analysis of the experimental/modelled results is useful for understanding the combustion mechanisms under these conditions.

In this paper, a parametric study on the combustion process of a 2 liter supercharged intercooled direct injection Diesel engine is presented, aiming to improve performance and pollutant emissions at a representative operational condition. Future and actual european emission standards have been taken as a reference for optimization. The study is based on the results of experimental tests carried out on a single cylinder research engine, where all the operating conditions are kept under severe control, and on the results of a phenomenological combustion model adjusted to the tested engine.