scholarly journals Aging aerosol in a well-mixed continuous-flow tank reactor: an introduction of the activation time distribution

2019 ◽  
Vol 12 (5) ◽  
pp. 2647-2663 ◽  
Author(s):  
Franz Friebel ◽  
Amewu A. Mensah
Keyword(s):  
Continuous Flow ◽  
Experimental Approach ◽  
Cloud Condensation Nuclei ◽  
Experimental Results ◽  
Mathematical Framework ◽  
Activation Time ◽  
Mean Values ◽  
Tank Reactor ◽  
Atmospheric Aging ◽  
Observation Times

Abstract. Two approaches are commonly used to simulate atmospheric aging processes in the laboratory. The experiments are either performed in large aerosol chambers (several m3) in order to achieve extended observation times or in small chambers (< 1 m3), compensating for the short observation times by elevated reactant concentrations. We present an experimental approach that enables long observation times at atmospherically relevant reactant concentrations in small chamber volumes by operating the aerosol chamber as a continuous-flow stirred tank reactor (CSTR). We developed a mathematical framework that allows the retrieval of data beyond calculating mean values, such as O3 exposure or equivalent atmospheric aging time, using the new metric, activation time (tact). This concept was developed and successfully tested to characterize the change in cloud condensation nuclei (CCN) activity of soot particles due to heterogeneous ozone oxidation. We found very good agreement between the experimental results and the theoretical predictions. This experimental approach and data analysis concept can be applied for the investigation of any transition in aerosol particles properties that can be considered a binary system. Furthermore, we show how tact can be applied to the analysis of data originating from other reactor types such as oxidation flow reactors (OFRs), which are widely used in atmospheric sciences. The new tact concept significantly supports the understanding of data acquired in OFRs, especially those from deviating experimental results in intercomparison campaigns.

scholarly journals Aging aerosol in a well-mixed continuous flow tank reactor: An introduction of the activation time distribution

2018 ◽  
Author(s):  
Franz Friebel ◽  
Amewu A. Mensah
Keyword(s):  
Continuous Flow ◽  
Cloud Condensation Nuclei ◽  
Mathematical Framework ◽  
Atmospheric Conditions ◽  
Activation Time ◽  
Heterogeneous Oxidation ◽  
Mean Values ◽  
Tank Reactor ◽  
Observation Times ◽  
Ccn Activity

Abstract. Simulating atmospheric aging processes in the laboratory under atmospheric conditions typically requires large aerosol chambers (several m3) in order to achieve extended observation times. We developed an experimental approach that enables long observation times in small chamber volumes by operating the aerosol chamber in a Continuous Flow Stirred Tank Reactor (CSTR) mode. We present a mathematical framework which allows the retrieval of data beyond calculating mean values using the newly introduced metric activation time (tact). This concept was developed and successfully tested to characterize the change in cloud condensation nuclei (CCN) activity of soot particles due to heterogeneous oxidation with ozone. We show that this concept can be applied to other systems investigating non-gradual transitions. The change in CCN-activity was parameterized with tact and agreed well with theoretical predictions. Furthermore we show how tact can be applied for the analysis of data originating from other oxidation flow reactors widely used in atmospheric sciences. This concept allows to explain discrepancies found in intercomparison of different chambers.

scholarly journals Quantifying the reactive uptake of OH by organic aerosols in a continuous flow stirred tank reactor

2009 ◽  
Vol 11 (36) ◽  
pp. 7885 ◽  
Author(s):  
Dung L. Che ◽  
Jared D. Smith ◽  
Stephen R. Leone ◽  
Musahid Ahmed ◽  
Kevin R. Wilson
Keyword(s):  
Continuous Flow ◽  
Organic Aerosols ◽  
Stirred Tank ◽  
Stirred Tank Reactor ◽  
Tank Reactor

scholarly journals Continuous-Flow Processes for the Production of Floxacin Intermediates: Efficient C–C Bond Formation through a Rapid and Strong Activation of Carboxylic Acids

2020 ◽  
Vol 02 (03) ◽  
pp. e128-e132
Author(s):  
Shao-Zheng Guo ◽  
Zhi-Qun Yu ◽  
Wei-Ke Su
Keyword(s):  
Reaction Time ◽  
Continuous Flow ◽  
Flow System ◽  
Bond Formation ◽  
Product Yield ◽  
Raw Material ◽  
Material Consumption ◽  
Tank Reactor ◽  
Mild Conditions ◽  
Flow Processes

AbstractThe development of highly efficient C–C bond formation methods for the synthesis of ethyl 2-(2,4-dichloro-5-fluorobenzoyl)-3-(dimethylamino)acrylate 1 in continuous flow processes has been described, which is based on the concept of rapid and efficient activation of carboxylic acid. 2,4-Dichloro-5-fluorobenzoic acid is rapidly converted into highly reactive 2,4-dichloro-5-fluorobenzoyl chloride by treating with inexpensive and less-toxic solid bis(trichloromethyl)carbonate. And then it rapidly reacts with ethyl 3-(dimethylamino)acrylate to afford the desired 1. This process can be performed under mild conditions. Compared with the traditional tank reactor process, less raw material consumption, higher product yield, less reaction time, higher operation safety ensured by more the environmentally friendly procedure, and process continuity are achieved in the continuous-flow system.

Experimental Study of a Tanker Ship Squat in Shallow Water

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
Mohammadreza Fathi Kazerooni ◽  
Mohammad Saeed Seif
Keyword(s):  
Experimental Study ◽  
Shallow Water ◽  
Experimental Approach ◽  
Model Tests ◽  
Ship Hull ◽  
Experimental Results ◽  
Shallow Waters ◽  
Towing Tank ◽  
Ship Model

One of the phenomena restricting the tanker navigation in shallow waters is reduction of under keel clearance in the terms of sinkage and dynamic trim that is called squatting. According to the complexity of flow around ship hull, one of the best methods to predict the ship squat is experimental approach based on model tests in the towing tank. In this study model tests for tanker ship model had been held in the towing tank and squat of the model are measured and analyzed. Based on experimental results suitable formulae for prediction of these types of ship squat in fairways are obtained.

The continuous flow stirred tank reactor (CFSTR) model and used oil volume corrections in condition monitoring

1997 ◽  
Vol 30 (4) ◽  
pp. 271-274 ◽  
Author(s):  
J.A. Bagshaw ◽  
Malcolm F. Fox ◽  
C.J. Jones ◽  
D.James Picken ◽  
Karl D.R. Seare
Keyword(s):  
Condition Monitoring ◽  
Continuous Flow ◽  
Stirred Tank ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
Used Oil

Growth Mechanism vs Matter Transport in Thermally Growing Oxides on High Temperature Materials: A Brief Survey Based on the Case Study of Alumina Formers

2009 ◽  
Vol 289-292 ◽  
pp. 385-395 ◽  
Author(s):  
Jerzy Jedlinski
Keyword(s):  
Growth Mechanism ◽  
Experimental Approach ◽  
Experimental Results ◽  
Metallic Materials ◽  
High Temperature Materials ◽  
Matter Transport ◽  
Alumina Formers ◽  
Microstructure Morphology ◽  
The Relationship

This paper reviews briefly the relationship between the growth mechanism and matter transport using as an example the best currently applied metallic materials being alumina formers. The attention is paid to the experimental approach as well as to the interpretation procedure of experimental results. The scale structure, microstructure, morphology and phase composition are indicated as factors strongly affecting its growth mechanism. The attempt is made to elucidate the possible relationships between the obtained experimental results and actual scale growth mechanisms operating during oxidation exposures.

scholarly journals CFD Study on Impeller Effect on Mixing in Miniature Stirred Tank Reactor

CFD letters ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 15-26
Author(s):  
Adnan Ghulam Mustafa ◽  
Mohd Fadhil Majnis ◽  
Nor Azyati Abdul Muttalib
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Calcium Alginate ◽  
Alginate Beads ◽  
Experimental Results ◽  
Stirred Tank ◽  
Stirred Tank Reactor ◽  
Calcium Alginate Beads ◽  
Tank Reactor ◽  
Simulation Results

Mixing of fluid can happen in existence or absence of impeller which will affect the mixing performance. The hydrodynamics behavior of fluid has a strong effect on the mixing. The design of mixing systems and operation using the agitated tanks is complicated because it is difficult to obtain accurate information for turbulence’s impeller induced. Computational Fluid Dynamics can be used to provide a detailed comprehension of those systems. This paper describes the effect of various designs of impeller in miniature stirred tank reactor towards the mixing of the calcium alginate beads with the milk using Computational Fluid Dynamics (CFD) software, ANSYS Fluent 19.2. The four different type of impellers are edge beater, 5-turbine blade, t-shape, and paddle. The impeller was simulated at different speeds of 150 rpm, 250 rpm, and 300 rpm. K-epsilon turbulence model was employed to simulate the flow distribution pattern of calcium alginate beads and the Multiple Reference Frame approach was used for the impeller rotation’s simulation. The simulation results obtained have a good agreement with the experimental results in term of vortex formation. The simulation results obtained for contour plots were fitted well with the experimental results as well as with pattern of impeller flow which was also studied. As a result, an optimal design of the impeller that is able to produce good mixing can be achieved using CFD analysis. The results obtained after performing the simulation proved that edge beater blade outperformed the other impellers and took the least time to fully distribute the calcium alginate beads in the tank at 250 rpm compared to 150 and 300 rpm. It can also be concluded that the edge beater blade is the best for the mixing of two-phase fluid and also produces mixed pattern flow. The obtained results from CFD can also be used to scale up the mixing process in larger systems.

scholarly journals Large increases in N<sub>cn</sub> and N<sub>ccn</sub> together with a nucleation-modeparticle pool over the northwestern Pacific Ocean in the spring of 2014

2019 ◽  
Author(s):  
Juntao Wang ◽  
Yanjie Shen ◽  
Kai Li ◽  
Yang Gao ◽  
Huiwang Gao ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Size Distribution ◽  
Cloud Condensation Nuclei ◽  
Northwestern Pacific ◽  
Northwestern Pacific Ocean ◽  
Mean Values ◽  
Rapid Changes ◽  
Order Of Magnitude ◽  
Marine Areas ◽  
Urban Sites

Abstract. The updated concentrations of atmospheric particles (Ncn) and the concentrations of cloud condensation nuclei (Nccn) over the northwestern Pacific Ocean (NWPO) were important to accurately evaluate the influence of aerosol outflow from the Asian continent on the climate by considering rapid changes in emissions of air pollutants therein. However, field observations were scarce in the last two decades. We conducted a cruise campaign over the NWPO to simultaneously measure Ncn, Nccn and the size distribution of aerosol particles from DOY 81 to DOY 108 of 2014. The mean values of Nccn at supersaturation (SS) of 0.2 % and 0.4 % were 0.68 ± 0.38×103 cm−3 and 1.1 ± 0.67×103 cm−3, respectively, with an average for Ncn of 2.8 ± 1.0×103 cm−3 during the cruise over the NWPO, which were all approximately one order of magnitude larger than spring observations from two decades ago in the atmosphere of remote marine areas. The higher values, against the marine natural background reported in the literature, implied an overwhelming contribution from continental inputs. The calculated CCN activity ratios were 0.30 ± 0.11 and 0.46 ± 0.19 at SS of 0.2 % and 0.4 %, respectively, which were almost the same as those of upwind semi-urban sites. High Nccn and CCN activities were observed from DOY 98 to 102, when the oceanic zone received even stronger continental inputs. During the whole cruise period with the exclusion of biomass burning and dust aerosols, a good correlation between Nccn at 0.4 % SS and the number concentrations of > 60 nm particles (N> 60 nm), with the slope of 0.98 and R2 = 0.94, was obtained, and the corresponding effective hygroscopicity parameter (k) was estimated as 0.40. The bimodal size distribution pattern of the particle number concentration was generally observed during the entire campaign when the N> 90 nm varied largely. However, the N

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