Diffusion-Limited Versus Quasi-Equilibrium Aerosol Growth
Diffusion-Limited Versus Quasi-Equilibrium Aerosol Growth
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扩散限制与准平衡气溶胶生长
DOI：
10.1080/02786826.2012.679344
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发表时间：
2012
影响因子：
5.2
通讯作者：
J. Seinfeld
中科院分区：
文献类型：
--
作者：
X. Zhang;S. Pandis;J. Seinfeld
气相物质凝聚成颗粒物是大气气溶胶演化的主要途径。描述二次有机气溶胶形成的传统方法是假设半挥发性有机化合物在气相和颗粒相之间的瞬时分配平衡。由于气相化学，随着物种的蒸汽浓度增加，生长发生。这种凝聚增长机制(准平衡增长)的基本数学基础一直缺乏。对于开放和封闭系统，得到了准平衡增长和不可逆扩散限制增长过程中有机气溶胶粒子尺寸分布演化的解析解。当环境水蒸气浓度的变化率比局部气溶胶平衡的建立速率慢时，准平衡增长成为半挥发分凝结的极限情况。结果表明，在特定情况下的生长机制可能从演变的尺寸分布特征中推断出来。在某些条件下，单一物种在最初的单峰分布上凝聚时，可能会出现双峰分布。版权所有2012美国气溶胶研究协会
Condensation of gas-phase material onto particulate matter is the predominant route by which atmospheric aerosols evolve. The traditional approach to representing formation of secondary organic aerosols (SOAs) is to assume instantaneous partitioning equilibrium of semivolatile organic compounds between gas and particle phases. Growth occurs as the vapor concentration of the species increases owing to gas-phase chemistry. The fundamental mathematical basis of such a condensation growth mechanism (quasi-equilibrium growth) has been lacking. Analytical solutions for the evolution of an organic aerosol size distribution undergoing quasi-equilibrium growth and irreversible diffusion-limited growth are obtained for open and closed systems. The quasi-equilibrium growth emerges as a limiting case for semivolatile species condensation when the rate of change of the ambient vapor concentration is slow compared with the rate of establishment of local gas-aerosol equilibrium. The results suggest that the growth mechanism in a particular situation might be inferred from the characteristics of the evolving size distribution. In certain conditions, a bimodal size distribution can occur during the condensation of a single species on an initially unimodal distribution. Copyright 2012 American Association for Aerosol Research