EXPERIMENTAL INVESTIGATION OVER CLOSED-LOOP COMBUSTION CONTROL POTENTIALITY FOR MITIGATING THE IMPACT OF ALTERNATIVE DIESEL FUELS ON PERFORMANCE AND EMISSIONS OF A EURO5 AUTOMOTIVE DIESEL ENGINE

摘要

The present work was dedicated to investigate the effects of 1st and 2nd generation biodiesels on performance, emissions and fuel consumption of a modern diesel engine, the GM Powertrain 2.0L 4-cylinder in-line common-rail which is Euro5 certified. This engine is particularly interesting since it features the closed-loop combustion control, i.e. the possibility to control, cycle-by-cycle and cylinder-by-cylinder, the phasing and amount of injected fuel in order to match the target MFB50 and IMEP, respectively. It was of significant interest, therefore, to assess the capability of closed-loop combustion control to compensate the drifts in MFB50 and IMEP triggered by variations in ignition properties as well as lower heating value between the reference diesel fuel and the alternative diesel fuel mixtures being tested. The experimental study has been carried out using various blends of alternative/reference diesel fuels in key operating points representative of the NEDC cycle and full load operation, both with combustion closed loop control activated and deactivated. Tests showed that closed-loop combustion control has potentiality to recover the drift in performance and NO_x emissions that high biodiesel blendings trigger, while retaining the significant advantage in PM reduction typical of biodiesel fuelling.