Domestic Wood Heating Appliances with Environmental High Performance: Chemical Composition of Emission and Correlations between Emission Factors and Operating Conditions

If the use of biomass and wood in particular replaces the fossil fuels for the heat production, this has to be made in conditions controlled to minimize the environmental and health impacts. Two recent French domestic appliances presenting high technology of adjustment of different hot air entrances (secondary and postcombustion) were tested with regard to their particulate and gaseous pollutants (total suspended particles (TSP), particulate matter with diameter below 2.5 mu m (PM2.5), carbon monoxide (CO), and total hydrocarbons compounds (THC)) for different heat output and combustion phases. Characterization of particulate composition consisted of determining the total carbon (TC) fraction, and its repartition between organic (OC) and elementary (EC) carbon, polycyclic aromatic hydrocarbons (PAH), and wood tracers. Analyses of PAH in the gas phase were also performed. Differences in the proportion of EC/OC in TSP were observed during a wood load: particles are mainly constituted of organic carbon during the inflammation phase. The carbon fraction of the particles at the end of the load decreases to about 20% with approximately half of organic carbon. Levoglucosan is the major biomass tracer present in the solid phase of TSP. Light PAH are predominant in the gas phase, with the naphthalene representing 75% of the total, whereas heavy PAH with cycle numbers from 5 to 7 are mainly present in the solid phase of TSP. However, considering the toxic equivalent factor, the human health impact of adsorbed and gaseous PAH is almost the same. In these conditions, emission factors of CO and TSP were below the minimal values imposed by the highest level of the environmental French label "Flamme Verte" and future European regulations that should come into force in 2022.