Chiara Guido

Assessment of Closed-Loop Combustion Control Capability for Biodiesel Blending Detection and Combustion Impact Mitigation for an Euro5 Automotive Diesel Engine

The present paper describes the results of a cooperative research project between GM Powertrain Europe and Istituto Motori - CNR aimed at studying the impact of both fresh and highly oxidized Rapeseed Methyl Ester (RME) at different levels of blending on performance, emissions and fuel consumption of modern automotive diesel engines featuring Closed-Loop Combustion Control (CLCC). In parallel, the capability of this system to detect the level of biodiesel blending through the use of specific detection algorithms was assessed. The tests were performed on the recently released 2.0L Euro5 GM diesel engine for passenger car application equipped with embedded pressure sensors in the glow plugs. Various blends of fresh and aged RME with reference diesel fuel were tested, notably 20% RME by volume (B20), 50% (B50) and pure RME (B100). The tests on the multi-cylinder engine were carried out in a wide range of engine operating points for the complete characterization of the biodiesel performance in the New European Driving Cycle (NEDC). The results highlighted that there is not appreciable difference in terms of performance and emission between fresh and oxidized biodiesel, at all levels of blending. On the other hand, the capability of the CLCC control to detect biodiesel blending with reasonable accuracy and to implement the corrective actions for avoiding emission drift and performance losses was successfully demonstrated.

Analysis of Particle Mass and Size Emissions from a Catalyzed Diesel Particulate Filter during Regeneration by Means of Actual Injection Strategies in Light Duty Engines

The diesel particulate filters (DPF) are considered the most robust technologies for particle emission reduction both in terms of mass and number. On the other hand, the increase of the backpressure in the exhaust system due to the accumulation of the particles in the filter walls leads to an increase of the engine fuel consumption and engine power reduction. To limit the filter loading, and the backpressure, a periodical regeneration is needed. Because of the growing interest about particle emission both in terms of mass, number and size, it appears important to monitor the evolution of the particle mass and number concentrations and size distribution during the regeneration of the DPFs. For this matter, in the presented work the regeneration of a catalyzed filter was fully analyzed. Particular attention was dedicated to the dynamic evolution both of the thermodynamic parameters and particle emissions. The measurements were performed at the exhaust of a Euro 5 CR Diesel engine equipped with a Close Coupled DPF. The regeneration process was investigated in a point representative of an extraurban engine operating condition. The regeneration was managed by the electronic control unit (ECU). In particular, an injection calibration was implemented taking into account the engine and the filter features. The particle size distribution evolution during regeneration phase was measured in the size range 5-1000 nm using a differential mobility spectrometer. The particle mass concentration was monitored by means of a microsoot sensor. Particle mass and number concentrations strongly increase during the regeneration process. Moreover, a high concentration of the number of particles smaller than 30nm was observed in some critical phases of the regeneration process.

The Effect of “Clean and Cold” EGR on the Improvement of Low Temperature Combustion Performance in a Single Cylinder Research Diesel Engine

In the present paper, the effect of the clean and cold EGR flow on the performance of a diesel engine running under Low Temperature Combustion conditions is investigated by means of experimental tests on a single-cylinder research engine. The engine layout was “ad hoc” designed to isolate the effect of the clean and cold recirculated gas flow on the combustion quality. The results have shown the possibility to increase the EGR rate by EGR flow temperature reduction, with a decrement of both NOx and PM emissions, at the same fuel consumption, highlighting that the intake manifold temperature is the main factor affecting the engine performances.

The Key Role of the Closed-loop Combustion Control for Exploiting the Potential of Biodiesel in a Modern Diesel Engine for Passenger Car Applications

The present paper describes the results of a cooperative research project between GM Powertrain Europe and Istituto Motori CNR aimed at studying the capability of GM Combustion Closed-Loop Control (CLCC) in enabling seamless operation with high biodiesel blending levels in a modern diesel engine for passenger car applications. As a matter of fact, fuelling modern electronically-controlled diesel engines with high blends of biodiesel leads to a performance reduction of about 12-15% at rated power and up to 30% in the low-end torque, while increasing significantly the engine-out NOx emissions. These effects are both due to the interaction of the biodiesel properties with the control logic of the electronic control unit, which is calibrated for diesel operation. However, as the authors previously demonstrated, if engine calibration is re-tuned for biodiesel fuelling, the above mentioned drawbacks can be compensated and the biodiesel environmental inner qualities can be fully deployed. In order to enable such calibration re-tuning, it is fundamental to achieve a reliable biodiesel blending detection, and to use it for realtime combustion optimization, chiefly by optimizing the injection train. Therefore, the authors investigated the capability of CLCC to detect biodiesel blending ratio on the recently released 2.0L Euro5 GM diesel engine equipped with embedded pressure sensors in the glow plugs. Various blends of biodiesel were tested, notably 20% by volume (B20), 50% (B50) and pure biodiesel (B100). Tests on the multicylinder engine were carried out in a wide range of engine operating points for the complete characterization of the biodiesel performance in the NEDC cycle. The results demonstrated the successful capability of the CLCC control to detect biodiesel blending with reasonable accuracy and to implement the corrective actions to avoid emission drift and performance losses.

The Key Role of the Electronic Control Technology in the Exploitation of the Alternative Renewable Fuels for Future Green, Efficient and Clean Diesel Engines

Great concerns are growing up on environmental impact of fossil fuel and poor air quality in urban areas due to traffic-related air pollution. In the last years, special attention was paid mainly to particulate matter (PM) and NOx emissions of diesel engines since these pollutants are associated to environmental and health issues. In particular, NOx contributes to the formation of ozone and acid rains and PM could cause injuries to the pulmonary and the cardiovascular systems. Nowadays, the overall concern about the global warming determines an increased interest also for CO2 emissions, one of the major greenhouse gas (GHG). In this respect, a significant improvement can be reached with the increased use of ‘‘clean’’ and renewable fuels. It is well known, in fact, that the use of biofuels can contribute to a significant well-to-wheel (WTW) reduction of GHG emissions. The most interesting biofuel is the biodiesel and the fuels synthesised from fossil or biogenic gas. Biodiesel designates a wide range of methyl-esters blends and is generally indicated with the acronym FAME, Fatty-Acid Methyl Esters. Biodiesel is produced from vegetable oils and animal fats through the transesterification, an energy efficient process that gives a significant advantage in terms of CO2 emission and that features both high energy conversion efficiency and fuel yield from processed oil. These two characteristics are the main responsible for the overall GHG emissions benefit of biodiesel in WTW analyses [1]. More recently, starting from the well-known Fischer-Tropsch synthesis process, another generation of alternative diesel fuel was developed. It is usually indicated with XTL, where X denotes the specific source feedstock and TL (to Liquid) highlights the final liquid state of the fuel. It has minor interferences with the human food chain, since non-edible biomasses can be employed or, in case of animal-edible biomasses, the whole plant can be processed, as for the cellulosic ethanol production. From the engine fuelling point of view, the significant difference between the two biofuels lies in their chemical composition. The first is essentially a blend of methyl-esters and the second of paraffin and olefin hydrocarbons. Because of the growing concerns about the energy crops impact on environment and food price, an increasing number of countries and stakeholders have recently challenged FAME biofuels. On the contrary, the XTL fuels, which

Soot particle size and pollutant emissions characterisation from an LD diesel engine equipped with high-pressure and low-pressure EGR system and operating with conventional and PCCI combustion

The paper analyses the soot Particle Size Distribution Function (PSDF) measurements carried out at the exhaust of a modern automotive diesel engine equipped with a low-pressure Exhaust Gas Recirculation (EGR) system and operating with conventional and Premixed Charge Compression Ignition (PCCI). The results have indicated significant benefits in terms of exhaust raw particle number emission with the adoption of low-pressure EGR system and PCCI calibration and, thanks to the peculiarity of the operating mode of Low Pressure EGR (LPEGR) system, have highlighted the complex link between in-cylinder charge composition and the PSDF characteristics.

Influence of the Air-Path Operating Parameters on the Low Temperature Combustion in a Single-Cylinder Diesel Engine

The present paper describes the effects of some air-path operating parameters on the performance of a modern common-rail diesel engine when it runs under Low Temperature Combustion (LTC) conditions. Aim of the experimental work was to explore the potential of the control of each parameter on the improvement of LTC application to the modern LD diesel engines for passenger cars, in order to meet future NOx emissions limits avoiding penalties in fuel consumption and drivability. In particular, the effects on LTC performance of the following operating parameters were analysed: intake air temperature, exhaust EGR cooler temperature, intake pipe pressure, exhaust pipe pressure and swirl ratio. Tests are carried out with a single-cylinder research diesel engine derived from FIAT 1.9 JTD 16V Multi-Jet in the EURO4 version. Results analysis have shown a significant influence of some examined parameters on the improvement of EGR tolerability, that has led to sensitive NOx reduction, within fixed limits in fuel consumption and smoke. On the contrary, engine behaviour is insensitive to the variation of the other air-path parameters.Copyright