Experimental investigations of combustion, performance and emission characterization of biodiesel fuelled HCCI engine using external mixture formation technique

In the present research, effect of biodiesel content on homogeneous charge compression ignition (HCCI) engine combustion, performance and emission characteristics has been investigated experimentally. Experiments were performed in a modified two cylinder engine, in which, one cylinder was operated in HCCI mode while other was operated in conventional CI mode. HCCI engine can be operated with a wide variety of fuels starting from mineral diesel to various blends of biodiesel (B20 and B40). The basic requirement of the HCCI engines is homogeneous mixing of fuel and air, which is done by using port fuel injection strategy in this study. An external device was used for fuel vaporization and mixture formation. For controlling HCCI combustion, different EGR conditions (0%, 15% and 30%) were also applied. In the experiments, combustion results were found to be more stable for biodiesel HCCI compared to diesel HCCI due to lower rate of heat release (RoHR) for biodiesel. A reduction in power output and an increase in ISFC were observed upon increasing the biodiesel content in the test fuel. A small increase in CO, HC and smoke emissions was observed with increasing biodiesel content due to slower evaporation rate of biodiesel. A significant reduction in NOx emissions was also observed with for biodiesel blends.