Particle emissions from pellets stoves and modern and old-type wood stoves

The purpose of this work is to characterise particle emissions from pellets stoves and modern and old-type residential wood stoves. The mass concentration of particulate material in the hot flue gas was 19–82 mg/MJ, roughly the same for wood stoves and pellets stoves, but the old-type wood stoves tended to emit even higher quantities. Furthermore, during combustion of wood logs the considerably higher emission of organic gaseous carbon indicates an additional contribution to the emission from secondarily formed condensable organic particles.The particle mass emitted was dominated by fine particles (<1 μm) in all cases. The fine particle maximum was displaced towards larger size during inefficient combustion, e.g. during the start-up phase. The number concentration of particles from wood stoves was 1.0·1014–6.0·1014 #/MJ, from pellets 3.0·1013–5.0·1013 #/MJ, and in all cases dominated by fine particles. Efficient combustion of pellets resulted mainly in inorganic particles, dominated by potassium sulphate and potassium chloride. Zinc, the second most frequent metal, and calcium showed the highest concentrations among the less volatile components. The lowest concentration detected was for cadmium, about 105 times lower than for potassium.

► The mass concentration of particles in the hot flue gas was roughly the same for wood stoves and pellets stoves.
► At combustion of wood logs, an additional contribution to the emission from secondarily formed condensable organic particles was indicated.
► In all cases the particle mass emitted was dominated by fine particles (<1 μm).
► The number of particles emitted was dominated by the ones smaller than 1 μm.