Particle Number and Size of Emissions during Realistic Operation of Two Residential Cordwood-Fired Hydronic Heaters

JAKE LINDBERG, Rebecca Trojanowski, Nicole Vitillo, Marilyn Wurth, Shida Tang, Gil H. LaDuke, Brian P. Frank, Patricia Fritz, Thomas Butcher, Devinder Mahajan, Brookhaven National Labs

     Abstract Number: 536
     Working Group: Biomass Combustion: Outdoor/Indoor Transport and Indoor Air Quality

Abstract
Operation and use of outdoor wood-fired hydronic heaters can pose a concern from an environmental health and safety as inefficient combustion of solid fuels, such as cordwood, can result in production of pollutant emissions. Wood-fired hydronic heaters are particularly concerning as they tend to have large combustion chambers and typical use patterns can result in long periods of low output, which result in sustained periods of high particle concentration aerosol emission.

In this study, we describe the particle number concentration and particle size distribution of the flue-gas aerosol emitted 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. Measurements of flue gas particulate number concentration and size for particles with aerodynamic diameters between 0.006 and 10 micrometers were made using a dilution sampling system. The measured particle number concentration in the flue gas was between 0.71 and 420 million particles per cubic centimeter. The majority of the particles had aerodynamic diameters less than 0.100 micrometers (particles of this size made up between 64% and 97% of all particles) and less than 1% of all particles had aerodynamic diameters greater than 1 micrometer. The particle number concentration and the particle size in the accumulation mode, between 0.100 and 1 µm, was dependent on fuel loading and heat output.