Characteristics of particle coagulation in an underground parking lot.
Particles in vehicle exhaust plumes in underground parking lots have adverse health effects due to the enclosed environment in which they are released and the temperature difference between the tailpipe and ambient environment; at the same time, particle coagulation might be obvious near the tailpipe in an underground parking lot. In the present study, airflow and temperature fields were calculated using the Realizable k-ε model, and the Eulerian particle transport model was selected in the numerical simulation of particle concentration dispersion. Polydisperse thermal coagulation due to Brownian collisions was employed to calculate the particle coagulation. The results show that particle coagulation rate and half-time were significant within 1 m from the tailpipe. The variations in the particle coagulation rate and half-time were similar, but their directions were opposite. Air exhaust time was nearly four times longer than averaged half-time and 40 times longer than minimum half-time. The peak particle diameter increased approximately 1.43 times due to coagulation. A double particle concentration at the tailpipe caused the fourfold rise in the particle coagulation rate in the distance ranging less than 1 m from the tailpipe. An increase in exhaust velocity at the tailpipe could shorten the obvious range of particle coagulation along the centerline of the tailpipe from 1 to 0.8 m in the study.
School of Municipal & Environmental Engineering, Harbin Institute of Technology, 73 Huanghe Street, Nangang District, Harbin, 150090, China.
Yu
Y
Zhao
Kato Lab and Ooka Lab, Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-Ku, Tokyo, 153-8505, Japan.
Shinsuke
S
Kato
School of Municipal & Environmental Engineering, Harbin Institute of Technology, 73 Huanghe Street, Nangang District, Harbin, 150090, China. zhaojn@hit.edu.cn.
Jianing
J
Zhao
D000393:Air Pollutants / Q000737:chemistry*; D004777:Environment; D005427:Flocculation; D008962:Models, Theoretical; D010316:Particle Size; D052638:Particulate Matter / Q000737:chemistry*; D013696:Temperature; D001335:Vehicle Emissions
D000393:Air Pollutants; D052638:Particulate Matter; D001335:Vehicle Emissions
Coagulation; Half-time; Particle size distribution; Ultrafine particle; Underground parking lot; Vehicle exhaust