AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
High-Frequency Size-Resolved Sampling of Aerosols from a Three-Stone Fire and a High-Efficiency Cookstove to Determine the Minimum Sampling Rate to Avoid Aliasing
DANIEL WILSON, Yungang Wang, Kathleen Lask, Ashok Gadgil, University of California, Berkeley
Abstract Number: 551 Working Group: Combustion
Abstract Worldwide, three billion people cook their food using biomass such as wood, charcoal, crop residues, and animal dung. Inhalation of emissions from this practice leads to four million premature deaths annually, mostly of women and children. Previous work to characterize the sized-resolved number concentration of disease-causing aerosol emissions from cooking fires has used slow-scanning instruments such as the scanning mobility particle sizer. In published literature, these instruments are reported to have taken more than two minutes to scan through the range of particle sizes from ~5 nm to ~ 500 nm in diameter. During the scan, these instruments could miss dynamic changes in aerosol emissions that occur on time scales faster than the scan frequency of the instrument. If all transient emissions from a cooking fire are not captured, these instruments and measurement techniques may alias time-resolved particle size distributions. In this study, we analyze wood combustion aerosols from both a three-stone fire and fuel-efficient, naturally-drafted cookstove using a fast mobility particle sizer. We utilize the fast sampling rate and broad size range of the fast mobility particle sizer, 1 Hz and 5.6 nm to 560 nm, respectively, to determine the minimum sampling rate necessary (Nyquist frequency) for aliasing-free analysis of cooking fire aerosol emissions. The Nyquist frequency for cooking smoke aerosol sampling is reported as a function of particle size. The determination of the minimum sampling rate for analyzing cooking fire emissions will inform the community about whether slow-scanning and less-expensive scanning mobility particle sizers are appropriate for analyzing cooking fire emissions, or if a more expensive instrument with a higher sampling rate is necessary to prevent aliasing.