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The monolithic DPF made of cordierite ceramic has unsatisfactory on his fatigue or long-term strength. A new design of configuration of plugs combined with the hexagonal channels shows a transversally isotropic property, and can remove the anisotropy of monoliths with square channels. This anisotropy is assumed to be one of main reasons for the failure of monoliths with square channels regarding the experimental results. Considering the honeycomb structure as a homogeneous material based on the Boltzmann continuum can't give the correct behaviour of this structure in a FEM simulation. Another homogenization procedure using the Cosserat theory has been discussed. The FEM stress analyses with structural detail-models show that the maximal tensile stresses in the monolith with square channels exist in the diagonal (i.e. 45°-) direction, or on the edges of channels. This feature is identical with what the theory has predicted and the experimental results have shown.

The emission of particulate matter from future GDI engines has to be optimized, to comply with more stringent emission standards such as EU6. Therefore, the mechanisms responsible for the formation of particles have to be analyzed in detail. The understanding of the in-cylinder processes, necessary for this purpose, can only be achieved by a complementary use of optically accessible single-cylinder engines as well as the numerical simulation. This however leads to great demands on the 3D flow simulation. In this paper the complete CFD approach, incorporating a detailed description of the entire underlying model chain is shown. Particularly the wall surface temperature and the temperature drop due to the interaction with liquid fuel spray were identified as important parameters influencing the spray-wall interaction and thus also the particulate emissions. Nevertheless, in conventional CFD models, the spray cooling cannot be captured because of an assumed constant wall temperature.

The 4th Workshop of the Engine Combustion Network (ECN) was held September 5-6, 2015 in Kyoto, Japan. This manuscript presents a summary of the progress in experiments and modeling among ECN contributors leading to a better understanding of soot formation under the ECN “Spray A” configuration and some parametric variants. Relevant published and unpublished work from prior ECN workshops is reviewed. Experiments measuring soot particle size and morphology, soot volume fraction (fv), and transient soot mass have been conducted at various international institutions providing target data for improvements to computational models. Multiple modeling contributions using both the Reynolds Averaged Navier-Stokes (RANS) Equations approach and the Large-Eddy Simulation (LES) approach have been submitted. Among these, various chemical mechanisms, soot models, and turbulence-chemistry interaction (TCI) methodologies have been considered.

Particulate emissions from Gasoline Direct Injection (GDI) engines have been an important topic of recent research interest due to their known environmental effects. This review paper will characterise the influence of different gasoline direct injection fuel systems on particle number (PN) emissions. The findings will be reviewed for engine and vehicle measurements with appropriate driving cycles (especially real driving cycles) to evaluate effects of the fuel injection systems on PN emissions. Recent technological developments alongside the trends of the influence of system pressure and nozzle design on injector tip wetting and deposits will be considered. Besides the engine and fuel system it is known that fuel composition will have an important effect on GDI engine PN emissions. The evaporation qualities of fuels have a substantial influence on mixture preparation, as does the composition of the fuel itself.

Due to the increasingly stricter emission legislation and growing demands for lower fuel consumption, there have been significant efforts to improve combustion efficiency while satisfying the emission requirements. Homogeneous Charge Compression Ignition (HCCI) combined with turbo/supercharging on gasoline engines provides a particularly promising and, at the same time, a challenging approach. Naturally aspirated (n.a.) HCCI has already shown a considerable potential of about 14% in the New European Driving Cycle (NEDC) compared with a conventional 4-cylinder 2.0 liter gasoline Port Fuel Injection (PFI) engine without any advanced valve-train technology. The HCCI n.a. operation range is air breathing limited due to the hot residuals required for the self-ignition and to slow down reaction kinetics, and therefore is limited to a part-load operation area.

Control of a car is lost, or considerably reduced, whenever one or more of the wheels exceed the stability limit during braking or accelerating due to excessive brake or drive slip. The problem of ensuring optimum stability, steerability and brake distance of a car during hard braking is solved by means of the well-known Anti-lock Braking System (ABS). The task to guarantee stability, steerability and optimum traction during acceleration, particularly on asymmetrical road surfaces and during cornering maneuvers, is being performed by the traction control system (ASR). Several means to provide an optimum traction control are described, e. g the control of engine torque by influencing the throttle plate and/or the ignition and/or the fuel injection.

Environmental consciousness and tightening emissions legislation push the market share of electronic fuel injection within a dynamically growing world wide small engines market. Similar to automotive engines during late 1980's, this opens up opportunities for original equipment manufacturers (OEM) and suppliers to jointly advance small engines performance in terms of fuel economy, emissions, and drivability. In this context, advanced combustion system analyses from automotive engine testing have been applied to a typical production motorcycle small engine. The 125cc 4-stroke, 2-valve, air-cooled, single-cylinder engine with closed-loop lambda-controlled electronic port fuel injection was investigated in original series configuration on an engine dynamometer. The test cycle fuel consumption simulation provides reasonable best case fuel economy estimates based on stationary map fuel consumption measurements.

The present paper concentrates on the option of catalytic autothermal reforming of gasoline for fuel cell applications. Major parameters of this process are the “Steam to Carbon Ratio” S/C and the air to fuel ratio λ. Computations assuming thermodynamic equilibrium in the autothermal reactor outlet (ATR) were carried out to attain information about their proper choice, as failure in adjusting the parameters within narrow limits has severe consequences on the reforming process. In order to quantify velocity distribution just ahead the catalyst and to evaluate mixing uniformity we designed an ATR featuring an optical access: Thus flow visualization using PIV (Particle Image Velocimetry) and LIF (Laser Induced Fluorescence) technique is possible. Preliminary PIV-results are presented and compared with CFD computations (Computational Fluid D ynamics).

The principle strategy, the development emphasis, and the investigation parameters of a DI gasoline engine are discussed. Several different combustion systems are briefly described and one system where the spark plug is located near the fuel injector is investigated. In addition, the influence of different operating parameters are studied. Some reasons for the improvement in the efficiency of a DI gasoline engine are shown with the help of thermodynamic analysis and simulation calculations. These show that at a constant operating point (engine speed = 2000 rpm, bmep = 2 bar) there is a reduction of the fuel consumption of 23% at unthrottled conditions in comparison to the homogeneous stoichiometric operation. In particular, the reduction of the pumping and heat losses and the reduction of the exhaust gas energy are responsible for this fuel consumption reduction.

This study presents measurements of transient flow field and spray structures inside an optically accessible DISI (direct-injection spark-ignition) internal combustion engine. The flow field has a direct effect upon mixture and combustion processes. Given the need to increase the efficiency and performance of modern IC engines and thus reduce emissions a detailed understanding of the flow field is necessary. The method of choice was high-speed two-component particle image velocimetry (PIV) imaging a large field of view (43 x 44 mm₂). To capture the temporal evolution of the main flow features the repetition rate was set to 6 kHz which resolves one image per 1° crank angle (CA) at 1000 rpm. The crank angle range recorded was the latter half of the compression stroke at various engine speeds as well as various charge motions (neutral, tumble and swirl). Moreover, consecutive cycles were recorded allowing a detailed investigation of cycle-to-cycle variations.

The selective catalytic reduction (SCR) based on urea-water-solution is an effective technique to reduce nitrogen oxides (NOx) emitted from diesel engines. A 3D numerical computer model of the injection of urea-water-solution and their interaction with the exhaust gas flow and exhaust tubing is developed to evaluate different configurations during the development process of such a DeNOx-system. The model accounts for all relevant processes appearing from the injection point to the entrance of the SCR-catalyst: momentum interaction between gas phase and droplets evaporation and thermolysis of droplets hydrolysis of isocyanic acid in gas phase heat transfer between wall and droplets spray/wall-interaction two-component wall film including interaction with gas phase and exhaust tube The single modeling steps are verified with visualizations, patternator measurements, phase-doppler-anemometer results and temperature measurements.

Engine management control systems basically consist of injection and ignition control. Additionally, closed loop control systems incorporating air fuel ratio control, automatic idle speed control and cylinder selective knock control have proven to be essential. To keep the performance stable during the car's lifetime, extensive use is made of self-adaptive strategies. As a new feature of engine management control, the self-adaptive canister purge control improves driveability and prevents the leakage of fuel vapors. To simplify the closed loop control algorithms primarily during transient operation conditions a sophisticated sequential fuel injection is added. The paper presents the aforementioned self-adaptive closed loop control strategies and the MOTRONIC MI. 3 ECU. Future development trends in engine management and drive train control demand powerful communication links like the Controller Area Network (CAN). This requirement and its planned realisation is discussed.

The fuel spray behavior in the near nozzle region of a gasoline injector is challenging to predict due to existing pressure gradients and turbulences of the internal flow and in-nozzle cavitation. Therefore, statistical parameters for spray characterization through experiments must be considered. The characterization of spray velocity fields in the near-nozzle region is of particular importance as the velocity information is crucial in understanding the hydrodynamic processes which take place further downstream during fuel atomization and mixture formation. This knowledge is needed in order to optimize injector nozzles for future requirements. In this study, the results of three experimental approaches for determination of spray velocity in the near-nozzle region are presented. Two different injector nozzle types were measured through high-speed shadowgraph imaging, Laser Doppler Anemometry (LDA) and X-ray imaging.

Dual-fuel combustion is an attractive approach for utilizing alternative fuels such as natural gas in compression-ignition internal combustion engines. In this approach, pilot injection of a more reactive fuel provides a source of ignition for the premixed natural gas/air. The overall performance combines the high efficiency of a compression-ignition engine with the relatively low emissions associated with natural gas. However the combustion phenomena occurring in dual-fuel engines present a challenge for existing turbulent combustion models because, following ignition, flame propagates through a partially-reacted and inhomogeneous mixture of the two fuels. The objective of this study is to test a new modelling formulation that combines the ability of the Conditional Moment Closure (CMC) approach to describe autoignition of fuel sprays with the ability of the G-equation approach to describe the subsequent flame propagation.

Future emission standards for heavy-duty vehicles like Euro 4, Euro 5, US '07 require advanced engine functionality. One contribution to achieve this target is the catalytic reduction of nitrogen oxides by injection of urea water solution to the exhaust gas. An overview on a urea dosing system, also called DENOXTRONIC, is given and a dosing strategy is described.

A fiber optical sensor system was used to detect the local fuel concentration in the vicinity of the spark position in a cylinder of a four-stroke SI production engine. The fuel concentration was determined by the infrared absorption method, which allows crank angle resolved fuel concentration measurements during multiple successive engine cycles. The sensor detects the attenuation of infrared radiation in the 3.4 μm wavelength region due to the infrared vibrational-rotational absorption band of hydrocarbons (HC). The absorption path was integrated in a modified spark plug and a tungsten halide lamp was used as an infrared light source. All investigations were carried out on a four-stroke spark ignition engine with fuel injection into the intake manifold. The measurements were made under starting conditions of the engine, which means a low engine speed. The engine operated with common gasoline (Euro Super) at different air/fuel-ratios.

To meet future CO₂ emissions limits and satisfy the bounds set by exhaust gas legislation reducing the engine displacement while maintaining the power output ("Downsizing") becomes of more and more importance to the SI-engine development process. The total number of cylinders per engine has to be reduced to keep the thermodynamic disadvantages of a small combustion chamber layout as small as possible. Doing so leads to new challenges concerning the mechanical design, the design of the combustion system concept as well as strategies maintaining a satisfying transient torque behavior. To address these challenges a turbocharged 2-cylinder SI engine with gasoline direct injection was designed for research purposes by Weber Motor and Bosch. This paper wants to offer an insight in the design process. The mechanical design as well as the combustion system concept process will be discussed.

Present knowledge of the velocity of the fuel in diesel sprays is quite limited due to the obscuring effects of fuel droplets, particularly in the high-density core of the spray. In recent years, x-ray radiography, which is capable of penetrating dense fuel sprays, has demonstrated the ability to probe the structure of the core of the spray, even in the dense near-nozzle region. In this paper, x-ray radiography data was used to determine the average axial velocity in diesel sprays as a function of position and time. Here, we report the method used to determine the axial velocity and its application to three common-rail diesel sprays at 250 bar injection pressure. The data show that the spray velocity does not reach its steady state value near the nozzle until approximately 200 μs after the start of injection. Moreover, the spray axial velocity decreases as one moves away from the spray orifice, suggesting transfer of axial momentum to the surrounding ambient gas.

A mean value soot model (MVSM) was developed and validated for the realtime prediction of the raw, engine-out soot emissions from common rail diesel engines. Through the consideration of five representative states during the combustion cycle, the developed MVSM determines the engine out soot emissions based on the soot formation and oxidation processes, using only parameters available from a standard engine control unit. 16 model parameters are used to describe the engine, fuel, and combustion characteristics, and must be determined for each engine and fuel combination. The MVSM was parameterized and validated using the measured soot emissions from two different engines operating with a total of three different fuels. After parameterization, the MVSM was capable of qualitatively and quantitatively reproducing the soot emissions for operating points throughout the entire operating map, including for operating regimes not considered during the parameterization.

The California Air Resources Board (CARB) has proposed procedures for the analysis of non-methane organic gases (NMOG) to determine the ozone forming potential (OFP) of automotive exhaust. For realization of these methods two differently configured GC systems are necessary. In order to reduce the efforts concerning costs, maintenance and quality control of two analytical instruments, a single run method is developed for routine analysis. This method allows identification and quantification of individual hydrocarbons (IHC) in the range of carbon numbers C2 to C12. Analytical problems arising from high contents of water and carbon dioxide in exhaust samples are discussed. Water reduction is obtained by a Nafion® Dryer by means of membrane diffusion of polar compounds. Contamination as well as memory effects due to this sample work up are described. Sample pre-concentration of 50-200 mL diluted automotive exhaust is performed using a triple phase “mixed bed” adsorption tube at O°C.