The Caltech Photooxidation Flow Tube reactor: design, fluid dynamics and characterization
The Caltech Photooxidation Flow Tube reactor: design, fluid dynamics and characterization
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DOI：
10.5194/amt-10-839-2017
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发表时间：
2017-03-09
影响因子：
3.8
通讯作者：
Seinfeld, John H.
中科院分区：
文献类型：
--
作者：
Huang, Yuanlong;Coggon, Matthew M.;Seinfeld, John H.
流管反应器被广泛用于研究气相大气化学和二次有机气溶胶（SOA）的形成。一种新的层流管反应器，加州理工学院光氧化流管（CPOT），用于气相大气化学和SOA的形成研究的发展，在这里报道。本工作解决的反应器设计的基础上的流体动力学特性和蒸汽分子和颗粒在反应器中的基本行为。基于计算流体动力学（CFD）模拟的反应器入口的设计包括静态混合器和锥形扩散器，以促进特征层流剖面的形成。为了评估实际性能在多大程度上符合理论计算流体力学模型，停留时间分布（RTD）实验报告与蒸汽分子（O-3）和亚微米硫酸铵颗粒。正如CFD预测所证实的，与严格等温条件的轻微偏差的存在导致反应器中的二次流，其产生与理想抛物线层流的偏差。表征实验，结合理论，提供了一个基础，解释大气化学和SOA的研究如下。在轴向分散平推流反应器（AD-PFR）框架内的1-D光化学模型制定在反应器中的氧化水平进行评估。模拟表明，OH浓度是均匀的沿着的反应器，和OH暴露（OHexp）范围从类似于109到类似于10（12）分子cm（-3）s可以实现从光解过氧化氢。本文提出了一种考虑轴向色散的光化学体系OHexp的计算方法。
Flow tube reactors are widely employed to study gas-phase atmospheric chemistry and secondary organic aerosol (SOA) formation. The development of a new laminar-flow tube reactor, the Caltech Photooxidation Flow Tube (CPOT), intended for the study of gas-phase atmospheric chemistry and SOA formation, is reported here. The present work addresses the reactor design based on fluid dynamical characterization and the fundamental behavior of vapor molecules and particles in the reactor. The design of the inlet to the reactor, based on computational fluid dynamics (CFD) simulations, comprises a static mixer and a conical diffuser to facilitate development of a characteristic laminar flow profile. To assess the extent to which the actual performance adheres to the theoretical CFD model, residence time distribution (RTD) experiments are reported with vapor molecules (O-3) and submicrometer ammonium sulfate particles. As confirmed by the CFD prediction, the presence of a slight deviation from strictly isothermal conditions leads to secondary flows in the reactor that produce deviations from the ideal parabolic laminar flow. The characterization experiments, in conjunction with theory, provide a basis for interpretation of atmospheric chemistry and SOA studies to follow. A 1-D photochemical model within an axially dispersed plug flow reactor (AD-PFR) framework is formulated to evaluate the oxidation level in the reactor. The simulation indicates that the OH concentration is uniform along the reactor, and an OH exposure (OHexp) ranging from similar to 109 to similar to 10(12) molecules cm(-3) s can be achieved from photolysis of H2O2. A method to calculate OHexp with a consideration for the axial dispersion in the present photochemical system is developed.