es301197d_si_001.pdf (287.27 kB)
Semivolatile and Volatile Organic Compound Emissions from Wood-Fired Hydronic Heaters
journal contribution
posted on 2012-07-17, 00:00 authored by Johanna Aurell, Brian K. Gullett, Dennis Tabor, Abderrahmane Touati, Lukas OudejansEmissions including polychlorinated dibenzo-p-dioxins
(PCDDs) and polychlorinated dibenzofurans (PCDFs), polyaromatic hydrocarbons
(PAHs), and volatile organic compounds (VOCs), were sampled from different
wood-fired hydronic heater (HH) technologies. Four commercially available
HH technologies were studied: a single-stage conventional combustor
with natural updraft, a three-stage downdraft combustion system, a
bottom-fed pellet burner, and a two-stage heater with both a combustion
and gasification chamber. The fuel consisted of three wood types (red
oak, white pine, and white ash), one hardwood pellet brand, and one
fuel mixture containing 95% red oak and 5% residential refuse by weight.
The various HHs and fuel combinations were tested in a realistic homeowner
fuel-charging scenario. Differences in emission levels were found
between HH technologies and fuel types. PCDD/PCDF emissions ranged
from 0.004 to 0.098 ng toxic equivalency/MJinput and PAHs
from 0.49 to 54 mg/MJinput. The former was increased by
the presence of 5% by weight refuse. The white pine fuel had the highest
PAH emission factor, while the bottom fed pellet burner had the lowest.
The major VOCs emitted were benzene, acetylene, and propylene. The
highest emissions of PAHs, VOCs, and PCDDs/PCDFs were observed with
the conventional unit, likely due to the rapid changes in combustion
conditions effected by the damper opening and closing.