1 research outputs found
Smoke Point Measurements of Diesel-Range Hydrocarbon–Oxygenate Blends Using a Novel Approach for Fuel Blend Selection
The
use of oxygenated fuels decreases particulate matter (PM) emissions
from diesel engines. Studies using engines, experimental flames, and
modeling have shown that the decrease in soot emissions depends on
the oxygenate molecular structure. To provide a better understanding
of the complex processes occurring in engines leading to PM emissions,
fundamental and systematic studies of the sooting tendency trends
for diesel-range hydrocarbon–oxygenate blends are needed. We
present a new approach to selecting fuel blends for sooting tendency
measurements that minimizes the confounding effect of dilution of
highly sooting components in the base fuel by maintaining constant
concentrations of those components in the blends. This novel approach
is illustrated by sooting tendency (smoke point) measurements in a
diffusion flame for a variety of diesel-range hydrocarbon–oxygenate
blends with different molecular structures. The oxygenates included
primary alcohols (1-butanol, 1-undecanol), diesters (dibutyl succinate,
dibutyl maleate), esters (methyl decanoate and methyl oleate), and
a glycol triether (triÂ(propylene glycol) methyl ether). The hydrocarbons
included an aromatic (1,2,4-trimethylbenzene), a straight-chain alkane
(<i>n</i>-hexadecane), and a highly branched alkane (2,2,4,4,6,8,8-heptamethylnonane).
The fuels were investigated as three-component blends, with an oxygenate
in a hydrocarbon base fuel consisting of a highly sooting hydrocarbon
component (1,2,4-trimethylbenzene) and a low-sooting hydrocarbon (<i>n</i>-hexadecane). The oxygen-extended sooting index (OESI)
provided sooting tendency trends that were generally consistent with
expectations for both hydrocarbon-only and oxygenated fuels. The dominant
chemical structure factors influencing the sooting tendency of the
hydrocarbons were aromaticity and branching. For the oxygenates, the
primary alcohols, the saturated monoester, and the glycol triether
exhibited the lowest sooting tendency, followed by the shorter-chain
diesters, and then the unsaturated monoester, with unsaturation increasing
the sooting tendency