Impact of Ethanol Blending Ratios on the Unregulated Emissions Issued from the Combustion of Diesel–Biodiesel–Ethanol Mixtures

A zero-dimensional model (Senkin) in conjunction with CHEMKIN II and the implementation of a high pressure PLOG function as well as the combination of two existing and broadly validated kinetic schemes for the oxidation of mixtures of n-heptane/methyl-decanoate/methyl-9-decenoate and ethanol were used to assess the effect of ethanol addition on the unregulated emissions as well as on their formation–depletion pathways under low- to intermediate-temperature conditions. The blended fuels were formed by incrementally adding 5% of ethanol to the neat n-heptane/methyl-decanoate/methyl-9-decenoate fuel, while keeping constant pressure and equivalence ratio. The principal objective of this work was to gain a fundamental understanding of the mechanisms through which ethanol oxygenate affects amounts of formaldehyde, acetaldehyde, acetylene and butadiene. It was found that amounts of carbonyls (CH₂O and CH₃CHO) were higher in ethanol blends as compared to the binary diesel-biodiesel fuel, whereas the opposite trend was observed for acetylene and butadiene.