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This paper reports the study of the effects of alternative diesel fuel and the impact for the air-fuel mixture preparation. The injection process characterization has been carried out in a non-evaporative high-density environment in order to measure the fuel injection rate and the spatial and temporal distribution of the fuel. The injection and vaporization processes have been characterized in an optically accessible single cylinder Common Rail diesel engine representing evaporative conditions similar to the real engine. The tests have been performed by means of a Bosch second generation common rail solenoid-driven fuel injection system with a 7-holes nozzle, flow number 440 cc/30s @100bar, 148deg cone opening angle (minisac type). Double injection strategy (pilot+main) has been implemented on the ECUs corresponding to operative running conditions of the commercial EURO 5 diesel engine.

An experimental evaluation of the impact of the diesel/biodiesel blends is presented in terms of engine performances and pollutant emission analysis. In-cylinder combustion evolution and injection law characterization were carried out on a single cylinder engine, on an optical single cylinder engine and on an injection test rig. Different diesel/biodiesel blends were tested at three operating points, representative of the NEDC cycle. Increasing the biodiesel percentage a reduction mainly in terms of smoke emission was observed. The engine performance as well as the other pollutant emissions were not substantially changed. Therefore this study confirms the benefits of the biodiesel use also on the current automotive engines, reducing simultaneously their environmental impact in terms of GHG and smoke emissions.