Abstract
In this study, two gasohols, namely, E15 [15% v/v ethanol blended with 85% v/v gasoline] and M15 [15% v/v methanol blended with 85% v/v gasoline] with respect to baseline gasoline were investigated for the characteristics of their soot particles. An in-depth comparative analysis for morphological characteristics of particulate matter emitted by a GDI engine using a high-resolution transmission electron microscope (HRTEM) was performed. Soot particles were collected using a partial flow dilution tunnel, and the effect of engine load and fuel oxygenated content on soot morphology was investigated. For soot samples from different test fuels, primary particle diameter (Dp), length, and width of the soot agglomerate and high angle annular dark field were investigated. At the macroscale (ratio of length to width of agglomerate L/W), the HRTEM images of gasoline soot agglomerates were observed to be remarkably similar to the agglomerates from gasohols; however, a detailed analysis of these images on the microscale (ratio of skeleton length to width of agglomerate Lsk/Wsk) showed them to be significantly different from each other. The mean primary particle (Dp) was found to be in the range of 20–32 nm for both loads and test fuels.
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