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The major challenge of the post-processing of soot aggregates in transmission electron microscope (TEM) images is the detection of soot primary particles that have no clear boundaries, vary in size within the fractal aggregates, and often overlap with each other. In this study, we propose an automated detection code for primary particles implementing the Canny Edge Detection (CED) and Circular Hough Transform (CHT) on pre-processed TEM images for particle edge enhancement using unsharp filtering as well as image inversion and self-subtraction. The particle detection code is tested for soot TEM images obtained at various ambient and injection conditions, and from five different combustion facilities including three constant-volume combustion chambers and two diesel engines.

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 Relevant published and unpublished work from prior ECN workshops is reviewed.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.

In the frame of tighter emission requirements and environmental protection, future standards will soon lead to the use of an OBD soot sensor to monitor DPF leakage. Such a sensor will first be introduced in the US by MY 2015 and then in Europe for Euro 6.2 in 2017. The resistive ceramic sensing technology has been selected by most OEM as the most appropriate. The sensor collects the soot in a time cumulative manner and has an internal heater to clean the ceramic before each measurement sequence. The actual challenge of the hardware is to design a wide band collecting system with a high sensitivity and repeatability circuit processing. Electricfil has overcome major drawbacks of the resistive technology with an innovative sensor tip, with filtration features and a boosting electronic scheme. This sensor integrates internal diagnostic capability at power on and during operation.

In the context of CO2 emissions reduction, investigations are currently made in various directions among the automotive sector: internal combustion engine efficiency improvement, downsizing, electrification, vehicle weight reduction. Meanwhile, a new type of vehicle is emerging in the automotive sector. This study analyses the perspectives and limitations of a low voltage electric vehicle (<60V), with only two people capacity. One of the main challenges of this new type of vehicle is to identify the best suited powertrain architecture, given the different constraints and needs (power, mass, acceleration, range, etc.). With the advantage of reducing the safety constraints linked to high voltage applications, but at the expense of higher currents when power level increases, a proper powertrain components sizing is mandatory, therefore limiting the advantages of such architecture.

Euro VI standards for heavy duty vehicles require the use of a DPF in order to comply with the particulate matter emission limit. Although passive regeneration of soot by NO2, promoted by a DOC located upstream the DPF, is preferred, the use of an active regeneration might be required whenever the soot mass trapped in the DPF increases. Some manufacturers made the choice of having a fuel injection in the exhaust system in order to generate an exothermic reaction in the DOC that helps to regenerate the particulate filter. This dedicated circuit avoids the use of in-cylinder post-injection which may induce oil dilution by diesel. The DPF regeneration is efficient and the DOC works durably if the exhaust diesel spray is completely vaporized before entering the DOC and is thoroughly mixed with the exhaust gases. However, ensuring complete evaporation and an optimum mixture distribution in the exhaust line is challenging.

Especially in view of more and more stringent emission legislation in passenger cars it is required to reduce the amount of pollutants. In the case of Diesel engines mainly NOx and PM are emitted during engine operation. The main influence factors for these pollutants are the in-cylinder oxygen concentration and the injected fuel amount. Typically the engine control task can be divided into two separate main parts, the fuel and the air system. Commonly air system control, consisting of a turbocharger and exhaust gas recirculation control, is used to provide the required amount of oxygen and address the emission targets, whereas the fuel is used to provide the desired torque. Especially in transient maneuvers the different time scales of both systems can lead to emission peaks which are not desired. Against this background in this work instead of the common way to address the air system, the fuel system is considered to reduce emission peaks during transients.

Due to its strong reliance on oil products, the transport sector is one of the major contributors to greenhouse gas emissions in Europe. To achieve long term targets proposed by recent regulations related to climate change measures, several studies are being conducted to reduce GHG emissions in road freight transport. In this context, hybrid vehicle technologies, already well developed for passenger cars and vans, have demonstrated a good potential of reducing fuel consumption also in medium and heavy-duty applications. Alternative fuels such as hydrogen have also demonstrated to be a good option to help reducing petroleum use and still ensure optimal performance. This study presents the feasibility of different hybrid architectures as counter options to a conventional long-haul truck powertrain, not only in terms of fuel economy but, in addition, from an economic point of view.