Impact of Dilution Ratio and Burning Conditions on the Number Size Distribution and Size-Dependent Mixing State of Primary Particles from Domestic Solid Fuel Burning

Dilution ratios (DRs) and burning conditions obviously affect particle number size distributions (PNSD), chemical compositions, and mixing states. These impacts for domestic solid fuel burning were investigated. For honeycomb briquettes, total particle number emission factors (EFPN) under DR150 for flaming and smoldering were (7.1 ± 0.8) × 1015 and (19.6 ± 5.9) × 1016 particles kg–1, respectively. Smoldering and flaming conditions promoted different emissions of organic species, mineral species, trace metals, and soot particles, impacting the following homogeneous nucleation or condensation and collision, which could explain their diversities in PNSD. The EFPN would be overestimated under DR150 and underestimated under DR100. Single particles were classified into carbonaceous particles, K–rich particles, Na–K particles, metal particles, and other particles. For coal burning, metal-containing particles dominated (9.5%–88.7%) the particles in the size range of 0.5–1.5 μm, with 3.7%–90.3% of them containing iron (Fe). Here, 93.1% of Fe particles were already internally mixed with sulfate, and high DR150 would promote their mixing. For crop residue and wood flaming, the mixed elemental and organic carbon (ECOC) particles dominated (87.1%–95.2%), with 74.7% and 45.1% of them containing levoglucosan. The PNSDs and mixing states of chemical species are helpful to update the initial settings of corresponding modeling studies.