• Energy Research

Abstract A biomass oil/diesel blend was prepared using an emulsion method and combusted in a diesel engine. An injector was then removed and the morphology, composition, and structure of the carbonaceous deposits on the pintle-type nozzle were characterized using a combination of HRTEM, SEM/EDAX, Raman and XRD. Results showed that the carbon deposition of the emulsified fuel with high crystallinity was greater than that of diesel. The agglomerated particulate diameters of the deposited carbon from diesel and emulsified fuel were approximately 10–30 μm and 50 μm, respectively. The carbon deposition mechanism from the emulsified fuel was attributed to the high oxygen content of the groups leading to increased polymerization and subsequent condensation on the nozzle surfaces that was then carbonised.

AbstractThe effects of a TiF3 catalyst on the tribological behaviour of carbon black-contaminated liquid paraffin and a fully formulated engine lubricating oil (CD SAE15W-40) were investigated using a four-ball tribological test. Scanning electronic microscopy with energy-dispersive spectroscopy, X-ray photoelectron spectroscopy, surface roughness, and thermogravimetric analyses were used to investigate the surface element content, chemical valence state, surface roughness, and initial decomposition temperature of the oil samples, respectively. Results showed that the average wear scar diameter (AWSD) and friction coefficient of the two kinds of carbon black-contaminated lubricants decreased in the presence of 0.5wt% TiF3. The variation rates of the carbon black-contaminated liquid paraffin and fully formulated engine lubricating oil were 29.45% and 11.54%, respectively, and their initial decomposition temperatures decreased. These phenomena were ascribed to the decomposition of TiF3 catalyst into TiO2 and fluoride that resulted in the formation of improved boundary lubrication films. Moreover, for the fully formulated engine oil, the lubrication additive zinc dialkyldithiophosphate was catalyzed by TiF3, decomposing into polyphosphate, which aided the formation of mixture boundary lubrication films.

AbstractBiomethane and biogas produced from waste (i.e., from an anaerobic digester) have shown themselves to be promising fuels for internal combustion engines. They can improve fuel security and ...

The lubricating properties of two sustainable alternative diesels blended with ultra low sulphur diesel (ULSD) were investigated. The candidate fuels were a biodiesel consisting of fatty acid methyl esters derived from rapeseed (RME) and gas-to-liquid (GTL). Lubricity tests were conducted on a high frequency reciprocating rig (HFRR). The mating specimen surfaces were analysed using optical microscopy and profilometery for wear scar diameters and profiles respectively. Microscopic surface topography and deposit composition was evaluated using a scanning electronic microscope (SEM) with an energy dispersive spectrometer (EDS). Like all modern zero sulphur diesel fuel (ZSD), GTL fuels need a lubricity agent to meet modern lubricity specifications. It has been proven that GTL responds well to typical lubricity additives in the marketplace. The lubricity of ULSD, GTL and blends of these fuels were significantly improved with the addition of as little as 10% volume of RME, inducing more stable hydrodynamic conditions. Topography measurements showed the formation of a residue when RME was blended in the base fuels and composition analysis indicated a predominately carbon formation on the worn surfaces that correlated with wear scar diameters. On the other hand, the test disc under GTL lubrication showed the smooth and residue free surface. The optimal proportion of blended fuel that created the smallest wear scar diameter was 70% GTL, 20% ULSD and 10% RME.

Abstract The tribological response of bio-oil derived from Spirulina algae has been assessed, according to the choice of catalyst during esterification. The bio-oil was upgraded over the selected catalysts of KF/HZSM-5 and KF/Al 2 O 3 with ethanol. Physical and chemical properties were assessed throughout with the crystal structure of the catalysts was characterized by X-ray diffraction (XRD), chemical groups and components of the bio-oil by Fourier Transform infrared spectroscopy (FTIR) and Gas Chromatograph–Mass Spectroscopy (GC–MS). Tribological experiments were conducted using a bespoke piston ring-on-cylinder liner tribometer. Worn surfaces were observed by Scanning Electron Microscope (SEM), and the elemental contents and valences were tested by X-ray Energy Dispersive Spectroscopy (EDS) and X-ray Photoelectron Spectroscopy (XPS). It is shown that choice of catalyst used during the upgrading of the bio-oil has a significant effect on tribological performance. Catalytic esterification improved friction resistance and the anti-wear properties of the bio-oil. KF/Al 2 O 3 was a better catalyst for doing this than KF/HZSM, a result of the ester and organic groups present in the KF/Al 2 O 3 upgraded bio-oil. These groups acted to form a protective tribo-film between surfaces.

Common rail (CR) diesel fuel injection systems are very sensitive to variations in fuel properties, thus the impact of alternative fuels on the durability of the injection system should be investigated when considering the use of alternative fuels. This work studies a high-pressure CR (HPCR) diesel fuel injection system operating for 400 h in an injection test bench, using a fuel blend composed of an alternative paraffinic fuel and conventional diesel (50PF50D). The alternative fuel does not have aromatic components and has lower density than conventional diesel fuel. The injection system durability study was carried out under typical injection pressure and fuel temperature for the fuel pump, the common rail and the injector. The results show that the HPCR fuel injection system and its components (e.g., piston, spring, cylinder, driveshaft and cam) have no indication of damage, wear or change in surface roughness. The absence of internal wear to the components of the injection system is supported by the approximately constant total flow rate that reaches the injector during the whole the 400 h of the experiment. However, the size of the injector nozzle holes was decreased (approximately 12%), being consistent with the increase in the return fuel flow of the injector and rail (approximately 13%) after the completion of the study. Overall, the injection system maintained its operability during the whole duration of the durability study, which encourages the use of paraffinic fuels as an alternative to conventional diesel fuel.

Due to the emission benefits of the oxygen in the fuel molecule, the interest for the use of ethanol as fuel blend components in compression ignition engines has been increased. However the use of fuel blends with high percentage of ethanol can lead to poor fuel blend quality (e.g. fuel miscibility, cetane number, viscosity and lubricity). An approach which can be used to improve these properties is the addition of biodiesel forming ternary blends (ethanol-biodiesel-diesel). The addition of castor oil-derived biodiesel (COME) containing a high proportion of methyl ricinoleate (C18:1 OH) is an attractive approach in order to i) reduce the use of first generation biodiesel derived from edible sources, ii) balance the reduction in viscosity and lubricity of ethanol-diesel blends due to the high viscosity and excellent lubricity of methyl ricinoleate.The fuel blend properties, gaseous and soot emissions, and particulate size distribution of ethanol-diesel blends with the addition of hydroxylated biodiesel derived from castor oil were investigated. Tests were compared with baseline experiments using rapeseed oil methyl ester (RME) which consists mainly of methyl oleate (C18:1) with the same number of carbon and unsaturation degree compared to methyl ricinoleate so that the hydroxyl group presenting in castor oil methyl ester can be evaluated. The results showed that the addition of castor oil methyl ester to ethanol-diesel blends is more effective to restore the lubricity of the fuel blend. A significant benefit in soot emissions was obtained from the combination of ethanol and hydroxylated biodiesel, while there was no penalty in regulated gaseous carbonaceous emissions. An improvement in NOX-soot trade-off was obtained by the COME blend compared to the RME blend.

This study relates to developing future alternative fuels and focuses on the effects of a fuel’s molecular structure on its properties and performance in advanced propulsion systems. The tribological performance of various biomass-derived oxygenated alternative fuels, including butanol, pentanol, cyclopentanol, cyclopentanone, and gasoline and their blends with diesel, was investigated. Lubricity tests were conducted using a high-frequency reciprocating rig (HFRR). Cyclopentanone-diesel and cyclopentanol-diesel blends result in smaller wear scar sizes compared to using their neat forms. A lower steel disc contaminated with the alternative fuels during the HFRR tests resulted in worn surface roughness values lower than those of the neat diesel by up to 20%. It is believed that these reductions are mainly due to the presence of the hydroxyl group and the carbonyl group in alcohols and ketones, respectively, which make them more polar and consequently helps the formation of the protective lubrication film on the worn moving surfaces during the sliding process. Overall, the results from this study indicate that environmentally friendly cyclopentanol and cyclopentanone are practical and efficient fuel candidates for future advanced propulsion systems.

Abstract Biodiesel fuel is known to improve the properties of alcohol-diesel blends for use in compression ignition engines. In this work the effects on combustion characteristics and emissions of preselected methyl esters (i.e. biodiesel components) have been assessed. The most representative individual fatty acid methyl esters (FAMEs) were added to alcohol blends in order to understand the effect of carbon chain length and degree of unsaturation on combustion and emissions. The effects of alcohol addition on the properties of fuel blends were also investigated using ethanol and butanol. Relating to the physical properties, emphasis was given to both stability and lubricity of alcohol-diesel blends. The results showed that 15% of all methyl esters was enough to avoid phase separation of alcohol-diesel blends and keep the wear scar diameter of the blends below the limitation required by the lubricity standard. For combustion, the use of alcohol blends shows a clear benefit in terms of CO and soot emissions with respect to biodiesel blends with the same oxygen content. Short carbon chain length and saturated methyl esters are recommended to improve alcohol blends. Comparisons between the alcohols, show that butanol rather than ethanol produces lower CO, THC and soot emissions.