Gasoline Effects on Spray Characteristics, Mixing and Auto- ignition Processes in a CI Engine under PPC Conditions J. Javier López, J M. García-Oliver, A. García and V. Domenech CMT- Motores Térmicos - Universidad Politécnica de Valencia, Camino de Vera s/n 46022 Valencia – SPAIN (*) CORRESPONDING AUTHOR: Dr. Antonio Garcia: angarma8@mot.upv.es Telephone: +34 963879659 Fax: +34 963877659 Abstract Recent research has shown that one of the paths to reduce pollutant emissions in diesel engines is to bring the operating conditions towards those of a gasoline engine, through homogeneous combustion and high octane fuels. Reduced soot, NOx, and fuel consumption are some of the benefits of using gasoline fuel combined with EGR in compression ignition engines in partially premixed combustion modes. Thus, a comparative study using diesel fuel and gasoline has been conducted focusing on the spray characteristics, mixing and autoignition process in these new combustion modes using a conventional diesel injection system. In this work, an experimental study has been carried out comparing the effects of penetration and cone angle under non-evaporating conditions for both fuels in a constant volume test rig. Besides, liquid length measurements and combustion process under partially premixed combustion (PPC) conditions in a single cylinder transparent engine have been done. The analysis of the results for both fuels shows no major differences on penetration and spray cone angle between them. Under vaporizing conditions, diesel spray exhibited a significantly longer liquid length than gasoline, due to the higher volatility of gasoline.