scholarly journals Numerical Analysis of an Impinging Jet Reactor for the CVD and Gas-Phase Nucleation of Titania

1993 ◽  
Vol 335 ◽  
Author(s):  
Suleyman A. Gokoglu ◽  
G. D. Stewart ◽  
J. Collins ◽  
D. E. Rosner
Keyword(s):  
Gas Phase ◽  
Impinging Jet ◽  
Gas Phase Reactions ◽  
Reactor Model ◽  
Deposition Rates ◽  
Numerical Predictions ◽  
Model Predictions ◽  
Phase Nucleation ◽  
Chemically Reacting ◽  
The Mathematical Model

AbstractWe model a cold-wall atmospheric pressure impinging jet reactor to study the CVD and gas-phase nucleation of TiO2 from a titanium tetra-iso-propoxide (TTIP)/oxygen dilute source gas mixture in nitrogen. The mathematical model uses the computational code FIDAP and complements our recent asymptotic theory for high activation energy gas-phase reactions in thin chemically reacting sublayers. The numerical predictions highlight deviations from ideality in various regions inside the experimental reactor. Model predictions of deposition rates and the onset of gas-phase nucleation compare favorably with experiments. Although variable property effects on deposition rates are not significant (∼11% at 1000K), the reduction of rates due to Soret transport is substantial (∼75% at 1000K).

Gas Phase and Surface Reactions in Mocvd of GaAs from Triethylgallium, Trimethylgallium, and Organometallic Arsenic Precursors

1988 ◽  
Vol 131 ◽  
Author(s):  
Thomas R. Omstead ◽  
Penny M. Van Sickle ◽  
Klavs F. Jensen
Keyword(s):  
Gas Phase ◽  
Low Temperatures ◽  
Surface Reactions ◽  
Rate Data ◽  
Gas Phase Reactions ◽  
Heated Zone ◽  
Model Predictions ◽  
First Time ◽  
Good Agreement

ABSTRACTThe growth of GaAs from triethylgallium (TEG) and trimethylgallium (TMG) with tertiarybutylarsine (tBAs), triethylarsenic (TEAs), and trimethylarsenic (TMAs), has been investigated by using a reactor equipped with a recording microbalance for in situ rate measurements. Rate data show that the growth with these precursors is dominated by the formation of adduct compounds in the gas lines, by adduct related parasitic gas phase reactions in the heated zone, and by the surface reactions. A model is proposed for the competition between deposition reactions and the parasitic gas phase reactions. Model predictions are in very good agreement with experimental data for all combinations of precursors except for TEG/TMAs where extensive gallium droplet formation is observed at low temperatures. Growth of reasonable quality GaAs with Hall mobilities of 7600 cm2/Vs at 77 K using TEG and tBAs is reported for the first time.

Study on Cold Start Influence Factors of Three Way Catalytic Converter

2013 ◽  
Vol 385-386 ◽  
pp. 172-175
Author(s):  
Hao Cai ◽  
Li Ping Yu ◽  
Jin Ke Gong ◽  
Yu He Geng ◽  
Ya Fei Liu
Keyword(s):  
Numerical Simulation ◽  
Ambient Temperature ◽  
Gas Phase ◽  
Catalytic Converter ◽  
Influence Factors ◽  
Cold Start ◽  
Gas Phase Reactions ◽  
Reactor Model ◽  
Exhaust Temperature ◽  
The Impact

This article has established a three-way catalytic converter reactor model of gas phase reactions and surface reactions. Based on this model, cold start transient emission numerical simulation has been done. The result shows that the influence of ambient temperature and exhaust temperature on the HC is much greater than the impact on the CO.

Models and Mechanisms of III-V Compound Semiconductor Growth by Movpe

1989 ◽  
Vol 145 ◽  
Author(s):  
Klavs F. Jensen ◽  
Triantafillos J. Mountziaris ◽  
Dimitrios I. Fotiadis
Keyword(s):  
Gas Phase ◽  
Surface Reactions ◽  
Transport Phenomena ◽  
Reaction Model ◽  
Reactor Performance ◽  
Gas Phase Reactions ◽  
Carbon Incorporation ◽  
Transport Reaction ◽  
Model Predictions ◽  
Good Agreement

AbstractA kinetic model for metalorganic vapor phase epitaxy (MOVPE) of GaAs from trimethylgallium and arsine is imbedded into two-dimensional transport phenomena descriptions of horizontal and vertical MOVPE reactors. The mechanism involves 15 gas-phase species, 17 gas-phase reactions, 9 surface species and 26 surface reactions. The surface reactions take into account different crystallographic orientations of the GaAs substrate. Carbon incorporation is predicted to occur via carbene containing species. A sensitivity analysis shows that only a few reactions are needed to simulate observed growth rates while the full mechanism is important in computing carbon levels in GaAs. The model predictions are in good agreement with data for trimethylgallium decomposition in hot isothermal tubes, with GaAs growth in horizontal reactors, and with carbon incorporation in vertical reactors. The transport-reaction model demonstrates that both gas-phase and surface reactions as well as transport phenomena are important in predicting MOVPE reactor performance.

Numerical modeling of the influence of bubbles on flow and heat transfer in the descending gas-liquid flow in a pipe

2012 ◽  
Vol 9 (1) ◽  
pp. 131-135
Author(s):  
M.A. Pakhomov
Keyword(s):  
Heat Transfer ◽  
Gas Phase ◽  
Liquid Flow ◽  
Bubble Diameter ◽  
Gas Content ◽  
Two Phase ◽  
Eulerian Description ◽  
Flow And Heat Transfer ◽  
Gas Liquid Flow ◽  
The Mathematical Model

The paper presents the results of modeling the dynamics of flow, friction and heat transfer in a descending gas-liquid flow in the pipe. The mathematical model is based on the use of the Eulerian description for both phases. The effect of a change in the degree of dispersion of the gas phase at the input, flow rate, initial liquid temperature and its friction and heat transfer rate in a two-phase flow. Addition of the gas phase causes an increase in heat transfer and friction on the wall, and these effects become more noticeable with increasing gas content and bubble diameter.

Gas-Phase Reactions

1981 ◽  
Author(s):  
Victor N. Kondratiev ◽  
Evgeniĭ E. Nikitin
Keyword(s):  
Gas Phase ◽  
Gas Phase Reactions

Influence of Gas Mixing and Heating on Gas-Phase Reactions in GaN MOCVD Growth

2012 ◽  
Vol 1 (1) ◽  
pp. P46-P53 ◽  
Author(s):  
Ran Zuo ◽  
Haiqun Yu ◽  
Nan Xu ◽  
Xiaokun He
Keyword(s):  
Gas Phase ◽  
Gas Mixing ◽  
Gas Phase Reactions ◽  
Mocvd Growth

scholarly journals How volatile components catalyze vapor nucleation

2021 ◽  
Vol 7 (3) ◽  
pp. eabd9954 ◽  
Author(s):  
Chenxi Li ◽  
Jan Krohn ◽  
Martina Lippe ◽  
Ruth Signorell
Keyword(s):  
Gas Phase ◽  
Molecular Level ◽  
Volatile Components ◽  
Transient Species ◽  
Gaseous Species ◽  
Alternative Pathways ◽  
Nucleation Mechanisms ◽  
Designed Experiment ◽  
Phase Nucleation ◽  
Vapor Nucleation

Gas phase nucleation is a ubiquitous phenomenon in planetary atmospheres and technical processes, yet our understanding of it is far from complete. In particular, the enhancement of nucleation by the addition of a more volatile, weakly interacting gaseous species to a nucleating vapor has escaped molecular-level experimental investigation. Here, we use a specially designed experiment to directly measure the chemical composition and the concentration of nucleating clusters in various binary CO2-containing vapors. Our analysis suggests that CO2 essentially catalyzes nucleation of the low vapor pressure component through the formation of transient, hetero-molecular clusters and thus provides alternative pathways for nucleation to proceed more efficiently. This work opens up new avenues for the quantitative assessment of nucleation mechanisms involving transient species in multicomponent vapors.

Gas Phase Reactions Activated by Nuclear Processes

1957 ◽  
Vol 79 (17) ◽  
pp. 4609-4616 ◽  
Author(s):  
Adon A. Gordus ◽  
John E. Willard
Keyword(s):  
Gas Phase ◽  
Gas Phase Reactions ◽  
Nuclear Processes
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