In this study, the compression ratio of a commercial 15L heavy-duty diesel engine was lowered and a split injection strategy was developed to promote partially premixed compression ignition (PPCI) combustion. Various low reactivity gasoline-range fuels were compared with ultra-low-sulfur diesel fuel (ULSD) for steady-state engine performance and emissions. Specially, particulate matter (PM) emissions were examined for their mass, size and number concentrations, and further characterized by organic/elemental carbon analysis, chemical speciation and thermogravimetric analysis. As more fuel-efficient PPCI combustion was promoted, a slight reduction in fuel consumption was observed for all gasoline-range fuels, which also had higher heating values than ULSD. Since mixing-controlled combustion dominated the latter part of the combustion process, hydrocarbon (HC) and carbon monoxide (CO) emissions were only slightly increased with the gasoline-range fuels. In contrast, soot emissions were significantly reduced with the gasoline-range fuels, including a ~70% reduction in micro soot sensor measurements and a >
50% reduction in smoke meter measurements. All gasoline-range fuel PM samples were also found to contain higher amount of volatile species and organic carbon fractions compared to ULSD PM samples as measured by thermogravimetric and EC-OC analyses. Various partially oxidized HC species and nitrophenolic compounds were also detected by TDP-GC-MS and CE-MS techniques, which implied that more pronounced PPCI combustion occurred with the gasoline-range fuels. As a whole similar PM oxidation behavior was observed despite the differences in reactivity and chemical properties of the fuels, even though there may be some significant impacts under certain operating conditions.