Inversely modeling homogeneous H2SO4 − H2O nucleation rate in exhaust-related conditions

Atmospheric Chemistry and Physics Discussions

Olin, Miska^1¹  Palmroth, Marja R. T.^3²  Alanen, Jenni^1,2³ 

[1]Aerosol Physics Laboratory, Physics Unit, Tampere University, P.O. Box 692, 33014 Tampere, Finland^1

[2]Bio and Circular Economy, Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 541, 33014 Tampere, Finland^3

[3]now at: AGCO Power, Linnavuorentie 8–10, 37240 Linnavuori, Finland^2

DOI  :  10.5194/acp-19-6367-2019

学科分类：大气科学

来源: Copernicus Publications

【 摘 要 】

The homogeneous sulfuric acid–water nucleation rate in conditions related to vehicle exhaust was measured and modeled. The measurements were performed by evaporating sulfuric acid and water liquids and by diluting and cooling the sample vapor with a sampling system mimicking the dilution process occurring in a real-world driving situation. The nucleation rate inside the measurement system was modeled inversely using CFD (computational fluid dynamics) and the aerosol dynamics code, CFD-TUTMAM (Tampere University of Technology Modal Aerosol Model for CFD). The nucleation exponents for the concentrations of sulfuric acid and water and for the saturation vapor pressure of sulfuric acid were found to be 1.9±0.1 , 0.50±0.05 , and 0.75±0.05 , respectively. These exponents can be used to examine the nucleation mechanisms occurring in exhaust from different combustion sources (internal combustion engines, power plant boilers, etc.) or in the atmosphere. Additionally, the nucleation rate can be expressed with the exponents as a function of the concentrations of sulfuric acid and water and of temperature. The obtained function can be used as a starting point for inverse modeling studies of more complex nucleation mechanisms involving extra compounds in addition to sulfuric acid and water. More complex nucleation mechanisms, such as those involving hydrocarbons, are observed with real vehicle exhaust and are also supported by the results obtained in this study. Furthermore, the function can be used to improve air quality models by using it to model the effect of sulfuric acid-emitting traffic and power generation on the particle concentration in urban air.

【 授权许可】

CC BY