Extending the environmental benefits of ethanol–diesel blends through DGE incorporation

The research focuses on the potential use of DGE (diethylene glycol diethyl ether), as a high-cetane number oxygenated additive to diesel-like fuels. Apart from evaluating its individual effects an investigation of how DGE can facilitate the use of bio-ethanol in diesel engines was conducted; which faces many technical difficulties, but can provide environmental advantages over biodiesel and conventional diesel fuel. Four partly renewable fuel blends with varying contents of DGE and ethanol were designed with overall diesel-replacement rate of 20%. DGE was found to reduce gaseous emissions, achieving a simultaneous reduction in both soot and NOx which highlighted the beneficial effects of its high cetane number and oxygen content. In ethanol–diesel blends small additions of DGE significantly enhanced blend stability and blend auto-ignition properties. Improvements in the NOx/soot trade-off characteristics were obtained for all blends. All tested blends produced lower particulate matter number concentrations and soot with characteristics that reduced their oxidation temperatures, hence providing benefits for diesel particulate filter (DPF) regeneration. Overall it was found that DGE fuel provides considerable energy and environmental benefits if used both as a single oxygenate with diesel or in multicomponent blends with ethanol and diesel

Improving Ethanol-Diesel Blend Through the Use of Hydroxylated Biodiesel

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

Effect of hydrogen on butanol–biodiesel blends in compression ignition engines

Research suggests that there is a dramatic reduction in CO and particulate matter (PM) emissions when butanol is blended with biodiesel derived from rapeseed oil (RME), but a small increase in THC emissions. The addition of hydrogen as a combustion enhancer can be used to counteract the increase in THC emissions seen with the butanol fuel blends and further reduce CO and PM emissions. The emission benefits with hydrogen addition were shown to be further improved for RME-butanol fuel blends. The penalty for using hydrogen is an increase in NOx emissions due to the increase in NO2 formation during combustion, but this is expected to have significant benefits in the function of aftertreatment systems. In this study, it is shown that the increase in engine-out NOx emissions can be effectively controlled through exhaust gas recirculation (EGR) without an excessive PM penalty thanks to the low PM concentration in the EGR (with an impeding PM recirculation penalty)