大气气溶胶颗粒物生成和演化的多相多组分微观动力学机理研究

The hazy weather is caused by atmospheric aerosol pollution which has the characteristics of multi-phase and multi-component. Current measures which have been taken to predict and control the disastrous haze mostly rely on source apportionment experiments. Based on the mechanism of heat and mass transfer, and chemical reaction at the interfaces of the aerosol particles, the main objective of this proposal is to study multiphase flow mechanisms of atmospheric aerosol particle nucleation, growth/concentration and coagulation. Firstly, the mechanism of nucleation will be elucidated using molecular simulations, and reasons for the differences between classical nucleation theory models and the previous experimental results will be explained. On this base, reasonable suggestions for the improvement of nucleation theoretical models will be proposed, systematically. Then, a kinetics model which treats explicitly all steps of mass transport and chemical reaction will be established based on the ideal of a multi-layer concept, while mechanisms and some important parameters will be analyzed by means of molecular modeling; mechanisms and prediction model for hygroscopic properties of aerosol will be presented; we will explore the microscopic mechanism of particle coalescence. According to the macroscopic flow characteristics of troposphere , a numerical model will be established to study the coagulation mechanism of aerosol particles under the complex flow field, which will clarify effects of the Brownian diffusion mechanism and turbulent flow field on coagulation process. At last, sub-processes of the dynamic evolution will be summarized, and then a three-dimensional dynamics prediction model will be set up. Besides, experiments will be designed to verify numerical simulation results. In summary，focusing on the transportation of heat and mass and the chemical reaction, the aim of this proposal is to resolve the interphase interactions and transport problems under multiphase and provide scientific basis of multiphase flow mechanics and chemical kinetics for the haze weather forecast and management.

雾霾灾害是由大气对流层中具有多相多组分特性的气溶胶颗粒群污染所致，当前对其预测与治理大多基于源解析实验。本项目拟从气溶胶颗粒的界面热质传递与化学反应机理出发，开展气溶胶成核、生长/浓缩和聚并过程的多相流动力学机理研究：基于分子模拟阐明成核发生机理及经典成核模型与已有实验结果存在较大差异的原因，为成核模型的改进提供合理建议；基于异质多相分层思想建立详细考虑相间热质传输和化学反应的生长/浓缩模型，基于分子模拟分析其中机理和重要参数；揭示颗粒吸湿特性影响机制并提出预测模型；探究颗粒聚并微观动力学机理，并从大气对流层宏观流动特性出发，建立复杂流场作用下气溶胶聚并数值模型，阐明布朗扩散和湍流流场对聚并的影响机理。最后，总结各子过程，建立完整的三维动力学模型，并实验验证模拟结果。项目旨在紧密围绕热质传输及化学反应过程，解决多相多组分背景下气溶胶多相相间作用机理与数理建模等关键科学问题，为雾霾的预报和治理提供多相流动力学及化学动力学基础科学依据。

气溶胶作为大气颗粒物中的重要组成成分，可以长期悬浮于大气环境中，对天气以及人体健康影响显著。气溶胶颗粒物组成复杂，对于其形成与生长等动力学过程的研究有助于揭示气溶胶的形成与演化机理，并且对于大气环境问题的防治具有重要的指导作用。本项目从气溶胶颗粒的界面热质传递与化学反应机理出发，开展气溶胶成核、生长/浓缩和聚并过程的多相流动力学机理研究：基于分子模拟阐明成核发生机理及经典成核模型与已有实验结果存在较大差异的原因，建立了更准确的成核模型，研究发现气溶胶颗粒物中离子与其过饱和度对气溶胶成核过程均有影响；建立颗粒吸湿特性预测模型，并通过高精度实验实现对高湿度气溶胶吸湿过程的研究，研究分析了温度、湿度、颗粒物成分对其吸湿过程的影响；在已有实验设备基础上，进行二次开发，改进HTDMA，提高了测量的精度，并用于环境以及标准样品的测量；利用实验室改造的设备，采集大气颗粒物，分析成分及其吸湿，吸光，毒理等特性，最终实现对大气颗粒物的源解析，并分析了大气颗粒物成分对环境及人体健康的影响。项目紧密围绕热质传输及化学反应过程，解决多相多组分背景下气溶胶多相相间作用机理与数理建模等关键科学问题，为雾霾的预报和治理提供多相流动力学及化学动力学基础科学依据。并通过实验分析，实现对大气颗粒物的源解析，以及各类特性分析，对于雾霾治理给出了指导方向。