Measurements of the characteristics of particle emissions from a port fuel injection engine

The characteristics of particle emissions from gasoline port fuel injection engines have not been fully investigated and established in comparison with those from direct-injection spark ignition engines. This paper aims to evaluate a new measurement system that could potentially be adapted later to allow a much wider examination of particulate production from port fuel injection engines relative to gasoline direct-injection engines. This work presents the morphology of the particles emitted from port fuel injection engines analysed using scanning transmission electron microscopy. The current designs of dilution tunnel used in particle morphology measurements were reviewed, and subsequently a new dilution tunnel was designed, built, tested and optimised for nanoparticle measurements from port fuel injection engines. A new methodology for capturing nanoparticles from port fuel injection engines for morphological analysis by transmission electron microscopy was investigated by integrating a nanoparticle impactor with a dilution tunnel. The performance of the dilution tunnel demonstrated that it integrated very well with the impactor and achieved the targets in terms of the flow rate and the temperature. The widest variety of particle morphologies, including liquid particles, was observed on the transmission electron microscopy grid from impactor plate A. In addition to soot agglomerates, crystalline particles and salt particles were also seen. In contrast with earlier studies, particle fragmentation was also observed.