Impact of rail pressure and biodiesel fueling on the particulate morphology and soot nanostructures from a common-rail turbocharged direct injection diesel engine

Abstract

An investigation of the impact of rail pressure and biodiesel fueling on exhaust particulate agglomerate morphology and primary particle (soot) nanostructure was conducted with a common-rail turbocharged direct injection diesel engine. The engine was operated at steady state on a dynamometer running at moderate speed with both low (30%) and medium-high (60%) fixed loads, and exhaust particulate was sampled for analysis. The fuels used were ultra-low sulfur diesel and its 20% v/v blends with soybean methyl ester biodiesel. Fuel injection occurred in a single event around top dead center at three different injection pressures. Exhaust particulate samples were characterized with transmission electronic microscopy imaging, scanning mobility particle sizing, thermogravimetric analysis, Raman spectroscopy, and Xray diffraction analysis. Particulate morphology and oxidative reactivity were found to vary significantly with both rail pressure and biodiesel blend level. Higher biodiesel content led to an increase in the primary particle size and oxidative reactivity but had no impact on nanoscale disorder in the as-received samples. For particulates generated with higher injection pressures, the initial oxidative reactivity increased, but there was no detectable correlation with primary particle size or nanoscale disorder.

Influence of waste cooking oil biodiesel on the nanostructure and volatility of particles emitted by a direct-injection diesel engine

“…Vander Wal and Tomasek (2004) and Hurt et al (2000) reported that the residence time, combustion temperature and soot precursor mass determine the nanostructure. However, Ye et al (2016) observed similar particulate nanostructure at different engine loads and different fuel injection pressures. They suggested that at high fuel injection pressures, higher combustion temperatures lead to a more ordered nanostructure, but the shorter residence time for soot formation contributes to a disordered nanostructure.…”

“…Salamanca et al (2012a) found insignificant difference in the mean primary particle diameters between diesel particles and biodiesel particles and the average diameter is 22 nm. Ye et al (2016) reported that the mean diameter of primary particles from B20 is around 30 nm which is 35-40% higher than that from diesel. Different results may be attributed to the different diesel engines and testing conditions used in the investigations (Ye et al 2016).…”

“…Ye et al (2016) reported that the mean diameter of primary particles from B20 is around 30 nm which is 35-40% higher than that from diesel. Different results may be attributed to the different diesel engines and testing conditions used in the investigations (Ye et al 2016).…”

“…On the other hand, some authors reported that the use of biodiesel has an insignificant effect in reducing the primary particle size (Turrio-Baldassarri et al 2004; Salamanca et al 2012a), or even causes an increase in the primary particle size (Ye et al 2016). Turrio-Baldassarri et al (2004) investigated the particle size distributions from a 6-cylinder direction-injection diesel engine fueled with pure diesel and B20 (20% rapeseed oil biodiesel and 80% diesel, v/v) and reported that the difference in the mean equivalent spherical diameters of diesel particles and B20 particles was insignificant.…”

“…However, some researchers reported different results for the effects of biodiesel on particulate nanostructure. Ye et al (2016) found that particles produced from B20 (20% soybean methyl ester biodiesel and 80% diesel, v/v) have nanostructures similar to those of particles produced from diesel. Salamanca et al (2012a) investigated the PM emissions from a diesel engine fueled with linseed biodiesel, palm biodiesel, and their blend (50% by volume).…”