Black and Brown Carbon Emissions during Realistic Operation of Two Residential Cordwood-Fired Hydronic Heaters
JAKE LINDBERG, Rebecca Trojanowski, Marilyn Wurth, Brian P. Frank, Shida Tang, Gil H. LaDuke, Thomas Butcher, Devinder Mahajan,
Brookhaven National Labs Abstract Number: 534
Working Group: Biomass Combustion: Outdoor/Indoor Transport and Indoor Air Quality
AbstractInefficient combustion of solid fuels, such as cordwood, produces large quantities of black and brown carbon (BC and BrC). These particle types are important as they have noted effects on health and the climate. Biomass combustion derived carbonaceous particulate matter is especially relevant in areas with a high proportion of wood combustion devices and geographic locations which are prone to air inversion events. Further realistic operating patterns for these devices, whereby most operators in a local area start their device at approximately the same time, and the fact that these devices produce much more pollution at start-up than during typical operating conditions, can lead to extremely high spatiotemporal concentrations of pollutant emissions, including BC and BrC. In this study, we describe the BC and BrC emissions from two residential cordwood hydronic heaters over a wide range of operating conditions, such as cold-starts, warm-starts, four different levels of output ranging from 15% to 100% maximum rated output, and periods of repeated cycling. The range in flue-gas BC concentrations, measured using an aethalometer at the 880 nanometer (nm) wavelength, were between 500 and 22,400 micrograms per cubic meter (ug/m3). Within this range the average value measured during cold-start was 3-6 times larger than the test average value. The BrC concentrations, measured using the 370 nm wavelength of an aethalometer, were between 90 and 35,600 ug/m3, where the cold-start average was greater than the BrC test average for one appliance/technology and lower for the other appliance. The calculated Angstrom Absorption Exponent (AAE) of the flue-gas aerosol ranged between 1.54 and 3.63, which is on the low end of accepted values for woodsmoke.