Nicola Del Giacomo

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.

Looking at New Concepts for Ultra-Low Emission Diesel Combustion System

The DI (Direct Injection) Diesel engine, which is inherently capable of achieving very low CO2 emissions, is affected by PM (Particulate Matter) that is the typical emission of turbulent diffusion flames and has the drawback of high NOx (nitrogen oxides) emissions. In Europe, the recent progress of diesel technology allows complying, with difficulty, with the EURO IV stage of European light duty vehicles regulation and limits planned for 2008 seem at the moment unachievable without a strong and innovative improvement of the combustion system configuration. In the present paper a new concept of highly diluted and low temperature combustion is presented and analyzed. In particular the mechanism of soot suppression at low flame temperature is achieved by the use of high-rate cooled exhaust gas recirculation. Tests were carried out on a medium duty engine equipped with a mechanical in-line injection pump and two modem common rail prototypes engines.Copyright

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