AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Observations of Two Reverse Particle Growth Pathways during the Char Burning Stage of Residential Coal Combustion
QING LI, Jingkun Jiang, Jianguo Deng, Lei Duan, Wei Zhou, Jiming Hao, Tsinghua University
Abstract Number: 383 Working Group: Combustion
Abstract Particle formation mechanism during residential coal combustion, a key anthropogenic source when addressing air quality and climate issues, has not been well understood. Particle formation and emission were characterized when burning Chinese bituminous and anthracite chunks in a typical residential stove. Aerosol size distributions in the range of 1 nm to 10 μm were monitored after a dilution tunnel that collects and dilutes flue gas from the stove chimney. Residential coal combustion can be divided into three stages, i.e., coal pyrolysis, burning of volatile compounds, and char burning. During the first two stages, accumulation mode particles (0.1 – 1 μm) and coarse mode particles (> 1 μm) are dominant in the aerosol mass based size distribution. Although most particulate mass (> 90%) are emitted in the first two stages, the char burning stage commonly lasts more than 80% time of a full residential coal combustion period and emits ultrafine particles with high number concentrations. Two reverse particle growth pathways were observed for all tested coal samples in the char burning stage when the burning temperature was decreasing. Nucleation mode particles (1 – 10 nm) and Aitken mode particles (10 – 100 nm) are dominant in both aerosol number and mass based size distribution. The first reverse growth pathway terminates at the burning temperature of about 600 oC, while the other pathway lasts till fire extinction (the burning temperature is close to ambient temperature). Offline chemical analysis of size-segregated particle samples helps to identify key inorganic species contributing to these two reverse particle growth pathways, i.e., alkali metal and ammonium salt appear to be high during the first and second pathways, respectively.