The laminar flow tube reactor as a quantitative tool for nucleation studies: Experimental results and theoretical analysis of homogeneous nucleation of dibutylphthalate

2000 ◽  
Vol 113 (9) ◽  
pp. 3704-3718 ◽  
Author(s):  
Vladimir B. Mikheev ◽  
Nels S. Laulainen ◽  
Stephan E. Barlow ◽  
Michael Knott ◽  
Ian J. Ford
Keyword(s):  
Laminar Flow ◽  
Theoretical Analysis ◽  
Homogeneous Nucleation ◽  
Experimental Results ◽  
Flow Tube ◽  
Tube Reactor ◽  
Quantitative Tool

scholarly journals The Caltech Photooxidation Flow Tube Reactor – I: Design and Fluid Dynamics

2016 ◽  
Author(s):  
Y. Huang ◽  
M. M. Coggon ◽  
R. Zhao ◽  
H. Lignell ◽  
M. U. Bauer ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Laminar Flow ◽  
Residence Time ◽  
Flow Model ◽  
Secondary Flows ◽  
Aerosol Formation ◽  
Flow Tube ◽  
Actual Performance ◽  
Tube Reactor ◽  
Laminar Flow Model

Abstract. Flow tube reactors are employed to study gas-phase atmospheric chemistry and secondary organic aerosol formation. A new laminar flow tube reactor, the Caltech PhotoOxidation flow Tube (CPOT), has been designed with the aim of achieving a well-characterized fluid dynamic and residence time environment. We present here the design and fluid dynamical characterization of the CPOT, based on the fundamental behavior of vapor molecules and particles in the reactor. The design of the inlet of the CPOT, which was based on computational fluid dynamics (CFD) simulations, comprises a static mixer and a conical diffuser to facilitate rapid development of the characteristic laminar flow parabolic profile. A CFD laminar flow model is developed to simulate the residence time distribution (RTD) of vapor molecules and particles in the CPOT. To assess the extent to which the actual performance adheres to the theoretical CFD model, RTD experiments were conducted with O3 and sub-micrometer ammonium sulfate particles. The measured RTD profiles do not strictly adhere to theory, owing to slightly non-isothermal conditions in the reactor, which lead to secondary flows. Introducing an enhanced eddy-like diffusivity for the vapor molecules and particles in the laminar flow model significantly improves the model-experiment agreement. These characterization experiments, in addition to the idealized computational behavior, provide a basis on which to evaluate the performance of the CPOT as a chemical reactor.

scholarly journals The Caltech Photooxidation Flow Tube reactor: design, fluid dynamics and characterization

2017 ◽  
Vol 10 (3) ◽  
pp. 839-867 ◽  
Author(s):  
Yuanlong Huang ◽  
Matthew M. Coggon ◽  
Ran Zhao ◽  
Hanna Lignell ◽  
Michael U. Bauer ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Laminar Flow ◽  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Reactor Design ◽  
Secondary Flows ◽  
Flow Profile ◽  
Flow Tube ◽  
Actual Performance ◽  
Tube Reactor

Abstract. 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 (O3) 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 ∼ 109 to ∼ 1012 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.

scholarly journals Homogeneous nucleation of sulfuric acid and water mixture: experimental setup and first results

2009 ◽  
Vol 9 (6) ◽  
pp. 23875-23907
Author(s):  
D. Brus ◽  
A.-P. Hyvärinen ◽  
Y. Viisanen ◽  
M. Kulmala ◽  
H. Lihavainen
Keyword(s):  
Sulfuric Acid ◽  
Laminar Flow ◽  
Theoretical Prediction ◽  
Acid Concentration ◽  
Homogeneous Nucleation ◽  
Sulfuric Acid Concentration ◽  
Experimental Setup ◽  
Water Mixture ◽  
Flow Tube ◽  
First Results

Abstract. In this study we introduce a new laminar flow tube suitable for binary and ternary homogeneous nucleation studies. The production of sulfuric acid and water vapor mixture, the experimental setup and the method of sulfuric acid concentration determination are discussed in details. Wall losses were estimated from the measured sulfuric acid concentration profile along the laminar flow tube and compared to a theoretical prediction. In this investigation the experimental evidence of new particle formation was observed at concentration of 109 molecules of sulfuric acid in cm3 and nucleation rates measured at three relative humidities (RH) 10, 30 and 50% cover six orders of magnitudes from 10−3 to 103 particles in cm3. Particle free air was used as a carrier gas. Our first results are compared to theoretical prediction of binary homogeneous nucleation, to results obtained by other investigators and to atmospheric nucleation.

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