The Bulk Density and Cohesion of Submicron Particles Emitted by a Residential Boiler When Burning Solid Fuels

Abstract

Particles emitted from combustion sources have a negative impact on human health and the environment. The solid fuel boilers that are used in households are a significant source of air pollution. The present study analyzes particulate matter (PM) produced during the combustion of wood pellets, wood logs, and coke in a residential boiler. The captured particles’ particle size distribution, bulk density, and cohesion are identified. A cascade impactor was used to capture the particles, and an optical digital microscope was used to determine the bulk density and cohesion (angle of repose) of the particles. The results show that the highest particle mass concentration emitted by the boiler falls within the interval of 89–146 nm, with the combustion of wood logs producing the most particles and coke combustion producing the least. The bulk density of particles of 51–595 nm (impactor stages 4–8) ranges from 320 to 785 kg/m3 for wood logs, 372–1108 kg/m3 for wood pellets, and 435–1330 kg/m3 for coke. The PM1 particles (impactor stage 4) have the highest bulk density. In the particle size range studied, the bulk density of particles decreases significantly with increasing particle size.