A study of mixture preparation and PM emissions using a direct injection engine fuelled with stoichiometric gasoline/ethanol blends

► The effect of gasoline/ethanol blends on PM emissions was investigated by measuring mixture inhomogeneity, combustion and spray vaporization characteristics. ► An increase in ethanol addition led to an increase in both particle number and mass. ► Cold spray plumes are more clearly defined and persist for longer than warm plumes. ► A warm engine exhibits less CoV of IMEP than a cold engine. ► Ethanol increased mixture inhomogeneity just before igniton.