Characterization and control of ash from diesel engine exhaust

1. Introduction
Ship emissions, particularly fine particulate matter (PM2.5), have a negative impact on air quality and pose serious health risks. This study examines whether a diesel generator can produce particulate emissions similar to those of a marine engine and the possibility to use the generator in further research related to Diesel Particulate Filters (DPFs). The primary goal of the study was to characterize the ash produced by the diesel engine. Diesel exhaust ash is a non-combustible residue resulting from the combustion of diesel fuel, lubricating oil, and engine wear.
2. Materials and methods
In the experimental part of the study, exhaust ash was generated using a diesel generator running on DMB fuel (a distillate marine fuel blend) mixed with ash-forming lubricating oil. The quantity and quality of ash was measured. The physical properties and the chemical composition of the exhaust ash were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). Additionally, gas emissions, soot levels, and particle number concentration and distribution were measured.
3. Results
The analysis found that using lubricating oil doped fuel increased the number of particles in the exhaust gas. Morphological studies identified various particle types, including nano-sized fuel particles, spherical lubricating oil particles containing calcium and agglomerated soot particles. Adding lubricating oil to the fuel reduced soot emissions presumably because the metal compounds in the oil facilitated the combustion of soot particles. Based on findings the properties of the particles generated by the diesel generator resemble to those obtained with marine engines using similar fuels.
4. Conclusions
The study highlights that fuel composition significantly impacts particulate emissions and their characteristics. The research suggests that diesel generators can be used in place of large ship engines for future studies on ash production and its effects on DPF. Additionally, the study poses an opportunity for developing more precise methods to measure ash concentration directly from exhaust gases, which could help predict DPF maintenance needs and optimize regeneration events.