Claudio Ciaravino

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.

Particle Number, Size and Mass Emissions of Different Biodiesel Blends Versus ULSD from a Small Displacement Automotive Diesel Engine

Introduction In order to ensure that emissions of ultrafine PM (0.1 μm and below) are controlled, a number based approach to PM emissions has been introduced, in addition to the actual mass based approach, in the Euro 5b/Euro 6 legislation [1]. The number and size distribution of a diesel engine are affected by the fuel characteristics[2]. European Directive 2009/28/EC depicts a new scenario concerning the share of energy from renewable sources in transport which will lead to the introduction of a share target, which should be achieved, by the European Union (EU) member states, by 2020 of 10% of the final energy consumption [3] A new generation of biodiesels is currently being explored in Asian countries. Despite the growing interest in biodiesel emissions, which is reflected by the large number of investigations and researches reported in literature, few studies have been carried out on last generation Euro 5 automotive engines [4]. An extension of the investigations to modern engines and aftertreatment systems, seems to be necessary to fully understand the effects of biodiesel usage and to avoid jeopardizing its potential emission benefits. The aim of this research is therefore to characterize the effects of two different biodiesels, sourced from rapeseed oil (RME) and jatropha oil (JME), and blended with ULSD, on both number and mass based particulate matter emissions, at the engine outlet of a modern, small displacement, common-rail, Euro 5 automotive diesel engine, for different engine operating conditions.

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.

Experimental Investigation on the Effects on Performance and Emissions of an Automotive Euro 5 Diesel Engine Fuelled with B30 from RME and HVO

The effects of using blended renewable diesel fuel (30% vol.), obtained from Rapeseed Methyl Ester (RME) and Hydrotreated Vegetable Oil (HVO), in a Euro 5 small displacement passenger car diesel engine have been evaluated in this paper. The hydraulic behaviour of the common rail injection system was verified in terms of injected volume and injection rate with both RME and HVO blends fuelling in comparison with commercial Diesel. Further, the spray obtained with RME B30 was analysed and compared with Diesel in terms of global shape and penetration, to investigate the potential differences in the air-fuel mixing process. Then, the impact of a biofuel blend usage on engine performance at full load was first analysed, adopting the same reference calibration for all the tested fuels. Afterwards, the effects of a biofuel blend usage on brake specific fuel consumption and on exhaust emissions were also evaluated at 7 different part load operating conditions, representative of the New European Driving Cycle. Finally, soot-NOx trade-off obtained by means of EGR sweeps were performed in the same operating points, in order to gather detailed information about further possible emissions benefits that could be achieved through a more extensive ECU recalibration.