scholarly journals CREATION OF MATHEMATICAL AND COMPUTER MODELS OF THE DYNAMICS OF FLAME PROPAGATION OF AIR-SUSPENDED SOLIDS IN VARIOUS ROCKS USING MATLAB ENVIRONMENT

2021 ◽  
Vol 445 (1) ◽  
pp. 29-34
Author(s):  
B. Alipova ◽  
B. Sapargaliyeva
Keyword(s):  
Flame Propagation ◽  
Reaction Rate ◽  
Suspended Solids ◽  
Concentration Limit ◽  
Explosion Chamber ◽  
Output Data ◽  
Velocity Fluctuations ◽  
Dynamic Formulation ◽  
One Step ◽  
Vented Explosion

The propagation of transient, air-suspended solids in a vented explosion chamber is numerically investigated by a dynamic formulation for the Concentration Limit of Flame Propagation (CLFP) with the GUI MATLAB environment. The geomechanics is modeled by a one-step overall reaction, which simulates the reaction of a stoichiometric propane– air-suspended solids. The CLFP modeling in the reaction rate model is numerically employed with mathematical models on basis Antoine's equation. This is based on an empirical correlation of the velocity fluctuations and implemented as interface with input-output data with graphic realization. The computer modeling show that the dynamic CLFP models provide superior results as general implementation of physical process of flame propagation and could be used for different rocks (f.e. granite, limestone, sandstone etc).

Droplet Factories: Synthesis and Assembly of Silver and Palladium Nanoparticles at the Liquid-Liquid Interface

2019 ◽  
Author(s):  
Suchanuch Sachdev ◽  
Rhushabh Maugi ◽  
Sam Davis ◽  
Scott Doak ◽  
Zhaoxia Zhou ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Reaction Rate ◽  
Tertiary Structure ◽  
Flow Reactor ◽  
Pd Nanoparticles ◽  
Subsequent Removal ◽  
Immiscible Liquids ◽  
Flow Reactors ◽  
Droplet Flow ◽  
One Step

<div>The interface between two immiscible liquids represent an ideal substrate for the assembly of nanomaterials. The defect free surface provides a reproducible support for creating densely packed ordered materials. Here a droplet flow reactor is presented for the synthesis and/ or assembly of nanomaterials at the interface of the emulsion. Each droplet acts as microreactor for a reaction between decamethylferrocene (DmFc) within the hexane and metal salts (Ag+/ Pd2+) in the aqueous phase. The hypothesis was that a spontaneous, interfacial reaction would lead to the assembly of nanomaterials creating a Pickering emulsion. The subsequent removal of the solvents showed how the Ag nanoparticles were trapped at the interface and retain the shape of the droplet, however the Pd nanoparticles were dispersed with no tertiary structure. To further exploit this, a one-step process where the particles are synthesised and then assembled into core-shell materials was proposed. The same reactions were performed in the presence of oleic acid stabilise Iron oxide nanoparticles dispersed within the hexane. It was shown that by changing the reaction rate and ratio between palladium and iron oxide a continuous coating of palladium onto iron oxide microspheres can be created. The same reaction with silver, was unsuccessful and resulted in the silver particles being shed into solution, or incorporated within the iron oxide micro particle. These insights offer a new method and chemistry within flow reactors for the creation of palladium and silver nanoparticles. We use the technique to create metal coated iron oxide nanomaterials but the methodology could be easily transferred to the assembly of other materials.</div><div><br></div>

Photo-Fenton Treatment of Olive Mill Wastewater Applying a Combined Fenton/Flocculation Pretreatment

2005 ◽  
Vol 129 (1) ◽  
pp. 53-59 ◽  
Author(s):  
W. Gernjak ◽  
T. Krutzler ◽  
R. Bauer
Keyword(s):  
Hordeum Vulgare ◽  
Reaction Rate ◽  
Suspended Solids ◽  
Olive Mill Wastewater ◽  
Solar Irradiation ◽  
Initial Value ◽  
Hordeum Vulgare L ◽  
Phenolic Substances ◽  
Parabolic Collector ◽  
Olive Mill

In this work, a pretreatment involving a combination of acidification, the Fenton method, and flocculation with polyelectrolytes was successfully applied to remove the suspended solids of Olive mill wastewater (OMW). This pretreatment strongly augmented the reaction rate in the following photo-Fenton treatment under solar irradiation in a Compound Parabolic Collector pilot-plant at Plataforma Solar de Almería. The content in phenolic substances could be degraded down to zero, while DOC was degraded down to about 25% of the initial value. In the work we describe different aspects concerning the process parameters of the pretreatment and the photo-Fenton treatment. Furthermore, decrease in phytotoxicity in the course of the treatment was monitored by germination tests with barley (hordeum vulgare L.). The results indicate that acute phytotoxicity can be substantially reduced by the application of the above mentioned pretreatment, enabling OMW to be used for ferti-irrigation in agriculture.

The theory of flame phenomena with a chain reaction

1956 ◽  
Vol 249 (957) ◽  
pp. 1-25 ◽  
Keyword(s):  
Reaction Zone ◽  
Flame Propagation ◽  
Reaction Rate ◽  
Laminar Flame ◽  
Combustible Mixture ◽  
Flame Speed ◽  
Spontaneous Ignition ◽  
Chain Reaction ◽  
Hydrazine Decomposition ◽  
A Chain

For single-step reactions there is a unique relation between reaction rate and reactedness for a given combustible mixture at a specified pressure and initial temperature. This paper examines whether the relation is still unique when chain reactions are present, by considering three types of flame—spontaneous ignition, laminar-flame propagation, and the homogeneous steady-flow reaction zone—with a chain-reaction scheme proposed by Adams & Stocks for the decomposition of hydrazine. It is found that the relation is not unique but that similarities exist between the relation for laminar-flame propagation and the relation for the homogeneous reaction zone. Incidentally, a general method of calculating laminar-flame speeds with reaction schemes of arbitrary complexity is presented. When applied to the hydrazine decomposition flame the predictions of the theory are in fair agreement with experimental results. In particular, the variation of flame speed with temperature is correctly predicted. It is shown that the use of the Karman-Penner 'steady-state assumption' would lead to an overestimate of the flame speed. Consideration of the changes which would result if the chain reaction should branch shows that there would once again tend to be a unique reaction rate versus reactedness relation, and that the laminar-flame speed would be increased by a factor of about three for the hottest flame considered but by larger factors for cooler flames.

Study of flame propagation in an external space under vented explosion conditions

Energy ◽  
2019 ◽  
Vol 178 ◽  
pp. 186-194 ◽  
Author(s):  
Song Sun ◽  
Mingyang Wang ◽  
Yanyu Qiu ◽  
Kanghua Gao
Keyword(s):  
Flame Propagation ◽  
External Space ◽  
Vented Explosion

Characteristic of Low Calorific Fuel Gas Combustion in Porous Burner by Preheating Air

2014 ◽  
Vol 624 ◽  
pp. 361-365 ◽  
Author(s):  
Min Hui Fan ◽  
Guan Qing Wang ◽  
Dan Luo ◽  
Ri Zan Li ◽  
Ning Ding ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Flame Propagation ◽  
Reaction Rate ◽  
Combustion Characteristic ◽  
Gas Combustion ◽  
Fuel Gas ◽  
Flame Propagation Velocity ◽  
Co Oxidation Reaction ◽  
Porous Burner ◽  
Reaction Region

The combustion characteristic of low calorific fuel gas was numerically investigated in porous burner by preheating air. Two-dimensional temperature profile, flame propagation precess, and CO reaction rate were analyzed detailly by preheating air, and compared with that of room air. The results showed that when the air is preheated, the combustion flame location locates to upstream, the maximum combustion temperature is higher than that of room air, and flame propagation velocity decreases.The CO oxidation reaction rate increases gradually with the radius distance increaing, but reaction region decreases. CO oxidation region guradually decreases and locates to the upstream with air preheating temperature increasing. Peaks of CO oxidation rate gradually change from two to one.

Study on Preparation and Hydrophobicity of MTES Derived Silica Sol and Gel

2012 ◽  
Vol 535-537 ◽  
pp. 2563-2566 ◽  
Author(s):  
Yu Ma ◽  
Hye Ryeon Lee ◽  
Toshinori Tsuru
Keyword(s):  
Reaction Rate ◽  
Sol Gel ◽  
Phase Segregation ◽  
Silica Sol ◽  
Molar Ratio ◽  
Modified Silica ◽  
Sol Gel Process ◽  
One Step ◽  
Inorganic Precursors

The synthesis of hydrophobic sol by one-step sol-gel process ammonia catalyzed was investigated. The water molar ratio and catalyst molar ratio were discussed to prevent phase segregation during the hydrolysis and co-condensation of the organic and inorganic precursors. The reactant system with water molar ratio 70 could make the reaction rate of MTES slightly less than that of TEOS, so that the hydrolysis - condensation – gelling reaction with MTES and TEOS as co-precursors could be synchronously. With the increase of the MTES/TEOS molar ratio, the reaction rate of the silica sol preparation decreased, the hydrophobicity of the sol and gel increased as the molar ratio MTES/TEOS change from 0.5~4. But the hydrophobicity of the methyl-modified silica sol and gel prepared with pure MTES in the sol-gel process were slightly lower than that of the methyl-modified silica sol and gel prepared with MTES and TEOS as co-precursors.

The Hydrosilylation and Cyanosilylation of Ketones Catalyzed using Metal Borohydrides

2019 ◽  
Vol 16 (2) ◽  
pp. 276-282 ◽  
Author(s):  
Yu Liu ◽  
Duodong Zhang ◽  
Yangyang Ma ◽  
Jiayun Li ◽  
Ying Bai ◽  
...  
Keyword(s):  
Carbonyl Compounds ◽  
Reaction Rate ◽  
Biologically Active ◽  
High Conversion ◽  
Similar Reaction ◽  
Reaction Conditions ◽  
Efficient Procedure ◽  
Hydrosilylation Reaction ◽  
One Step ◽  
Relative Catalytic Activity

Aim and Objective: The hydrosilylation reaction of carbonyl compounds has emerged as a powerful method in organic synthesis. The catalytic hydrosilylation of ketones is a valuable transformation because it generates protected cyanosilylation reaction of carbonyl compounds is an efficient procedure for the synthesis of silylated cyanohydrins, which are readily converted into useful functionalized compounds, such as cyanohydrins, α-hydroxy acids, β-amino alcohols and other biologically active compounds. Materials and Methods: A facile, economic and efficient method has been developed for the hydrosilylation and cyanosilylation of ketones using metal borohydrides. A series of silylated ethers and silylated cyanohydrins can be isolated via direct distillation. Results: The catalytic properties of a range of metal borohydrides in the hydrosilylation reaction of acetophenone with diphenylsilane were investigated. The relative catalytic activity of the borohydride catalyst studied was as follows: (CH3)4NBH4> (PhCH2)(CH3)3NBH4> (CH2CH3)4NBH4> (CH3CH2CH2CH3)4NBH4> NaBH4> KBH4> LiBH4. The cyanosilylation of acetophenone using trimethylsilyl cyanide (TMSCN) in the presence of NaBH4 occurred under similar reaction conditions. An excellent reaction rate and high conversion were obtained. Conclusion: The metal borohydride-catalyzed hydrosilylation alcohols in one step. The and cyanosilylation of ketones could be carried out smoothly under mild reaction conditions. Among the metal borohydrides studied, an excellent reaction rate and high conversion were obtained using NaBH4, NaBH (CH2CH3)3 or (alkyl)4 NBH4 as the reaction catalyst.

Nonlinear analysis of condensed-phase surface combustion

1990 ◽  
Vol 1 (1) ◽  
pp. 73-89 ◽  
Author(s):  
Marc Garbey ◽  
Hans G. Kaper ◽  
Gary K. Leaf ◽  
Bernard J. Matkowsky
Keyword(s):  
Reaction Rate ◽  
Melting Process ◽  
Axial Direction ◽  
Combustion Products ◽  
Multiple Point ◽  
Stability Properties ◽  
One Step ◽  
Spin Combustion ◽  
Phase Surface ◽  
The Stability

This article is concerned with the structure and stability properties of a combustion front that propagates in the axial direction along the surface of a cylindrical solid fuel element. The fuel consists of a mixture of two finely ground metallic powders, which combine upon ignition in a one-step chemical reaction. The reaction is accompanied by a melting process, which in turn enhances the reaction rate. The combustion products are in the solid state. The reaction zone, inside which the melting occurs, is modelled as a front that propagates along the surface of the cylinder. The different modes of propagation that have been observed experimentally (such as single- and multiheaded spin combustion and multiple-point combustion) are explained as the results of bifurcations from a uniformly propagating plane circular front. The stability properties of the various modes are discussed.

scholarly journals Sonochemical Deposition of Palladium Nanoparticles Onto the Surface of N-Doped Carbon Nanotubes: A Simplified One-Step Catalyst Production Method

2019 ◽  
Vol 150 (2) ◽  
pp. 505-513
Author(s):  
Ádám Prekob ◽  
Gábor Muránszky ◽  
István Kocserha ◽  
Béla Fiser ◽  
Ferenc Kristály ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Reaction Rate ◽  
Pd Nanoparticles ◽  
Production Method ◽  
Sonochemical Method ◽  
Nitrobenzene Hydrogenation ◽  
Step Procedure ◽  
One Step ◽  
Catalyst Production ◽  
Nitrogen Doped Carbon

Abstract This work presents an easy, one-step procedure for catalyst preparation. A small fraction of palladium ions was reduced to Pd nanoparticles and deposited onto the surface of nitrogen-doped carbon nanotubes (N-BCNT) by acoustic cavitation using high-intensity ultrasound in aqueous phase, where N-BCNT served as a reducing agent. The formation of elemental palladium and palladium oxides were confirmed and the particle size is < 5 nm. The catalytic activity of the synthesized Pd/N-BCNT catalyst was tested in nitrobenzene hydrogenation at four different temperature (273–323 K) and 20 bar pressure. The catalyst showed high activity despite the presence of palladium oxide forms, the conversion of nitrobenzene to aniline was 98% at 323 K temperature after 40 min. The activation energy was 35.81 kJ/mol. At 303 K and 323 K temperature, N-methylaniline was formed as by-product in a small quantity (8 mmol/dm3). By decreasing the reaction temperature (at 273 K and 283 K), the reaction rate was also lower, but it was favourable for aniline selectivity, and not formed n-methylaniline. All in all, Pd/N-BCNT catalyst was successfully produced by using a one-step sonochemical method, where further activation was not necessary as the catalytic system was applicable in nitrobenzene hydrogenation. Graphic Abstract

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