  The reduction and control of particulate matter generated by fossil fuel
combustion are among the main issues for actual and future combustion devices
due to the increasingly stringent emission regulations. Recently, various fuels
have been investigated as a potential substitute or additive for diesel and
gasoline. This work focuses on how oxymethylene ether-3 (OME3), the smallest
promising OME compound, affects carbon particulate formation when blended with
ethylene in burner-stabilized premixed flames at different equivalence ratios.
Particle size distribution (PSD) and Laser Induced Fluorescence (LIF) and
Incandescence (LII) along with numerical (Conditional Quadrature Method of
Moments - CQMOM, based on D'Anna physico-chemical soot model) investigations
were conducted to study particle formation and growth in pure ethylene and
ethylene/OME3 flames. The soot volume fraction and PSD indicate a reduction in
the total number and the size of the soot particles at all equivalence ratios,
while the number of small nanoparticles remains almost unchanged. The CQMOM
model is able to predict similar trends for the soot volume fraction and, using
the entropy maximization concept, the general shape of the PSD for both pure
ethylene and OME3-blended flames, compared to the experimental measurements.
Further, carbon particulate matter was thermophoretically sampled in the
highest equivalence ratio conditions and spectroscopically analyzed. The soot
structure was investigated using UV-Visible and Raman spectroscopy, finding a
slightly higher aromaticity for the pure ethylene soot. FTIR analysis showed
that carbon particulate matter produced from an OME3-doped flame contained
larger amounts of oxygen, mainly in the form of C=O.
