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This study aims to explore the impacts of the blending, fumigating, and combined fumigating+blending (F + B) methods, compared to the diesel method, on the engine combustion and cyclic variability parameters under five engine loads and speeds. The diesel and blending methods created heterogeneous combustion, while the fumigating and F + B methods created homogeneous+heterogeneous combustion. A fixed fuel composition of diesel-biodiesel-ethanol (D80B5E15, volume %) was used for the blending, fumigating, and F + B methods to maintain the same overall fuel composition for the comparison. It is found that all examined fueling methods have no pre-ignition and a similar trend for cumulative heat release fractions under all tested conditions. The blending method has similar, while the fumigating method has slightly longer overall combustion progression (from ignition delay to 95% of heat release) up to about 3 °CA in contrast to the diesel method. Compared to the diesel method, the blending (47.2 and 43.6%) and fumigating (22.3 and 22.2%) methods have longer premixed combustion phase, however a shorter diffusion combustion phase is achieved only by the blending method (−19.1 and −19.5%) and the fumigating method has no effect (1.7 and −1.3%) on it, according to the average results from five loads and speeds, respectively. Also, the blending (6.6 and 8.8%) and fumigating (26.3 and 53.5%) methods cause increase in COVIMEP. While, the blending method (9.2 and 6%) causes increase in COVMax(dP/dθ), and the fumigating method (−2.7 and −2.9%) leads to drop in COVMax(dP/dθ). The F + B method gets the results in between those of the fumigating and the blending methods. [ABSTRACT FROM AUTHOR]

This research explores the influence of renewable fuels, including three kinds of biodiesel along with ethanol on the physical properties and structural characteristics of particulate matter (PM) emitted from a diesel engine in comparison with pure diesel. After adding 10 vol% of grape seed biodiesel, coffee biodiesel and eucalyptus oil into diesel, three biodiesel blended fuels (10% grape seed biodiesel (DGs10), 10% spent coffee ground biodiesel (DC10) and eucalyptus oil biodiesel (DEu10)) were produced and tested in this study. Besides, one ethanol blend containing 9 vol% of ethanol and 1 vol% of biodiesel (blend stabilizer) was also tested to do the comparison. In the present study, scanning transmission electron microscope (STEM) and scanning electron microscope (SEM) were employed for analyzing the microstructure, nanostructure and electron diffraction pattern of PM. Raman spectrometer (RS) was also used for the analysis of structural characterization of PM. In addition, several experimental instruments like microbalance, measuring cup, viscometer, oxygen bomb calorimeter and Gas Chromatography-Mass Spectrometer (GC-MS) were employed to detect the fuel properties, including density, heating value, viscosity, composition and cetane number. A conclusion can be drawn that both biodiesel blends and ethanol blend have a changing effect on the PM properties compared to pure diesel, where biodiesel blends have a slightly weaker influence than ethanol blend. Regarding the biodiesel blends, DGs10 has more impact than DC10 and DEu10 in changes of PM properties, particularly in the reduction of PM mass, making it a good candidate for renewable fuel for diesel engines. [Display omitted] • Analyzing physical properties and structural characteristics of particle matter (PM). • Examining PM of diesel engine fueled with diesel, three biodiesel blends and ethanol. • Biodiesel and ethanol can impact the environment and human health through PM changes. • Ethanol blend has more influence than biodiesel blends on the PM properties changes. • DGs10 has more influence than DC10 and DEu10 on the PM properties changes. [ABSTRACT FROM AUTHOR]

The literature reveals that fossil fuels will continue to be the main energy source for transportation fleets up to 2050, despite their non-renewability and the emissions of pollutants resulting from their use. Until the full adoption of non-fossil and zero-emission vehicles (e.g., electric vehicles), the application of renewable liquid fuels could be the best choice due to the latter's positive effects such as reduced consumption of fossil fuels and reduced emissions of pollutants. Alcohols, among others, have been widely tested as alternative fuels in diesel engines, however, there is no comprehensive information about their impacts on particulate matter (PM) which has a direct influence on human health, the environment, and emission catalyst's efficiency. This review comprehensively explores the impact of lower/higher alcohols, from methanol to decanol, in dual-fuel mode on the PM physicochemical properties emitted from diesel engines under different alcohol ratios and operating conditions. It is observed that alcohols change the PM physical properties by reducing primary particle size/number, radius of gyration, fractal dimension, and fringe length and increasing fringe separation distance and tortuosity compared to those of diesel PM. Regarding the chemical properties, alcohols reduce polycyclic aromatic hydrocarbons, benzo[a]pyrene equivalent, organic carbon (OC), elemental carbon (EC), ions, and soot ignition temperature and increase OC/EC ratio and soot oxidation reactivity. Thus, each 10% of alcohol, by volume, has the potential to reduce PM mass, number, and size by about 17, 20, and 10%, while lower alcohols and blended mode have more impact than higher alcohols and fumigation mode, respectively. [Display omitted] • Impact of alcohols on particulate matter (PM) properties from CI engines are reviewed. • PM structure and chemical properties have strong effect on PM mass, number, and size. • Alcohol fuels can significantly change the physicochemical properties of diesel PM. • Lower alcohols have more impact than higher alcohols on PM properties. • Alcohols in blended format have more impact than fumigated format on PM reduction. [ABSTRACT FROM AUTHOR]

The present study investigates the impact of various alternative fuels, including biodiesel, methanol, ethanol, butanol and pentanol, on the micro and nano-structures, volatility and oxidation reactivity of particulate matter (PM) from a 4-cylinder compression ignition engine under low (10%) and high (80%) engine loads at a constant engine speed of 1800 rpm. Four alcohols were mixed with diesel and biodiesel to obtain ternary fuels. The overall oxygen concentration of each ternary fuel was fixed at 6% by mass for establishing the same condition for comparing. In addition to the ternary fuels, pure biodiesel was also compared with diesel fuel. The results of the micro and nano-structures characteristics obtained from a Scanning Transmission Electron Microscope (STEM) reveal that the alternative fuels can disorder the PM micro and nano-structures, and also the particles produced by these fuels have lower primary particle diameter, particle agglomerate size and fringe length, however, higher fringe tortuosity and almost equal (insignificant rise) fringe separation distance compared to those produced by diesel fuel. The results obtained from a Thermogravimetric Analyzer/Differential Scanning Calorimeter (TGA/DSC) show that both biodiesel and alcohols have the potential to increase in PM volatile substances and oxidation reactivity rate, and decrease in PM non-volatile substances in comparison with those of diesel fuel. It is concluded that the pure biodiesel has the highest impact on the PM structure, volatility and oxidation reactivity among all the tested alternative fuels, while methanol has the highest impact on these parameters among all the tested alcohol fuels. • PM structure, volatility and oxidation reactivity of diesel engine were analyzed. • Diesel, biodiesel, methanol, ethanol, butanol and pentanol fuels were tested. • Biodiesel has the highest PM volatility, oxidation reactivity and fringe tortuosity. • Biodiesel has the lowest non-volatile substances, particle size and fringe length. • After biodiesel, methanol blend has the highest effect on the PM parameters. [ABSTRACT FROM AUTHOR]