Characteristics of Particulate Matter Emissions for Low-Sulfur Heavy Oil Used in Low-Speed Two-Stroke Diesel Engines of Ocean-Going Ships

In this work, particulate matter (PM) emissions from a large two-stroke, low-speed marine diesel engine were investigated when the engine was operated with low-sulfur heavy fuel oil (HFO) at various loads. Particle samples were collected in situ from the engine exhaust to determine the detailed physical and chemical properties. The nanostructure and morphology of the nanoparticles were analyzed using transmission electron microscopy images (TEM). The results show that volatile organic carbon (OC) accounts for more than 80% in the HFO particles and leads to an increase in particle size. The thermodynamic conditions of a low-speed engine favor the behavior of capturing the soluble organic components. A large number of spherical char HFO particles with aerodynamic diameters of 0.2 μm–0.5 μm and a suspected inner metal core were detected. The two peak aerodynamic diameters of the HFO nanoparticles are 15 nm and 86 nm. The morphological differences among the HFO nanoparticles in varied engine conditions represent the formation process from primary nascent particles to mature graphitized particles caused by thermodynamics. The above study will be valuable for understanding the characteristics of PM emissions from low-sulfur HFO to achieve the ship PM emissions reduction target.