Hydrogen Recombiner: Theoretical Parametric Study

2002 ◽  
Author(s):  
Gilles Avakian
Keyword(s):  
Hydrogen Concentration ◽  
Total Pressure ◽  
Reaction Rate ◽  
Published Data ◽  
Geometrical Parameters ◽  
Surface Kinetics ◽  
Total Rate ◽  
Diffusion Controlled ◽  
Rate Of Reaction ◽  
Linear Behaviour

There is not yet published data concerning a complete overview of the behaviour of a SIEMENS recombiner versus the thermal hydrualic conditions and the geometry of the catalytic plates. This paper reports on a numerical behaviour of the recombiner depending on several gas parameters as the total pressure, and the hydrogen concentration, as well as geometrical parameters of the catalytic elements as the height and the spacing. We use a theoretical model validated by using the KALI experiments. In this model (Avakian, 1999), the reaction rate is diffusion-controlled, i.e. the contribution of surface kinetics to the total rate of reaction is neglected. We demonstrate a quasi-linear behaviour of the recombination rate vs. the total pressure and the hydrogen concentration. We display the benefit in using smaller catalytic plates instead of taller plates and we give an idea of the influence of the spacing between the catalytic plates.

Modelling complete methane oxidation over palladium oxide in a porous catalyst using first-principles surface kinetics

2018 ◽  
Vol 8 (2) ◽  
pp. 508-520 ◽  
Author(s):  
Carl-Robert Florén ◽  
Maxime Van den Bossche ◽  
Derek Creaser ◽  
Henrik Grönbeck ◽  
Per-Anders Carlsson ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
First Principles ◽  
Total Pressure ◽  
Reaction Rate ◽  
Palladium Oxide ◽  
Surface Kinetics ◽  
Porous Catalyst

Modeled turnover frequencies for varying temperature and total pressure combined with reaction rate controlling regions.

scholarly journals Experimental Investigation of Tandem Blade Cascades With Double-Circular ARC Profiles

1985 ◽  
Author(s):  
Wu Guochuan ◽  
Zhuang Biaonan ◽  
Guo Bingheng
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Mach Number ◽  
Total Pressure ◽  
Incidence Angle ◽  
Axial Direction ◽  
Geometrical Parameters ◽  
Optimal Conditions ◽  
Turning Angle ◽  
Circular Arc

24 double circular are tandem blade cascades of three different chord-ratios were investigated under different displacements in peripheral and axial direction. The inlet Mach number was 0.3. The Reynolds number based on blade chord was 2.7×105. The characteristics of the tandem blade cascades, such as the dependence of turning angle and coefficient of total pressure loss on incidence angle were obtained. The ranges of main geometrical parameters under optimal conditions were recommended.

Numerical Simulation of Air Flow in the State of Thermal and Chemical Nonequilibrium behind a Shock Wave Front

2021 ◽  
pp. 94-111
Author(s):  
A.I. Bryzgalov
Keyword(s):  
Shock Wave ◽  
Shock Front ◽  
Wave Front ◽  
Shock Wave Front ◽  
Reaction Rate ◽  
Vibrational Temperature ◽  
Pure Oxygen ◽  
Published Data ◽  
Calculation Results ◽  
Temperature Nonequilibrium

We used the model of a five-component air mixture flow behind the front of a one-dimensional shock wave to compute the flow parameters for shock front temperatures of up to 7000 K, taking into account the variable composition, translational and vibrational temperatures and pressure in the relaxation zone. Vibrational level population in oxygen and nitrogen obeys the Boltzmann distribution with one common vibrational temperature. We consider the effect that temperature nonequilibrium has on the chemical reaction rate by introducing a nonequilibrium factor to the reaction rate constant, said factor depending on the vibrational and translational temperatures. We compared our calculation results for dissociation behind the shock front to the published data concerning temperature nonequilibrium in a pure oxygen flow behind a shock wave front for two different intensities of the latter. The comparison shows a good agreement between the vibrational temperature, experimental data and calculations based on the experimental values of vibrational temperature and molality. We computed the parameters of thermodynamically nonequilibrium dissociation in the air behind the shock wave front, comparing them to those of equilibrium dissociation and calculation results previously published by others. The study demonstrates that the molality values computed converge gradually with those found in published data as the distance from the shock front increases. We list the reasons for the discrepancy between our calculation results and previously published data

scholarly journals PERIODATE OXIDATION OF PEG–600, AN ESSENTIAL PHARMACEUTICAL POLYMER

2019 ◽  
pp. 251-256
Author(s):  
K. V. S. KOTESWARA RAO ◽  
R. VENKATA NADH ◽  
K. VENKATA RATNAM
Keyword(s):  
Polyethylene Glycol ◽  
Oxygen Atom ◽  
Temperature Dependence ◽  
Reaction Rate ◽  
Periodate Oxidation ◽  
Alkali Concentration ◽  
Rate Of Reaction ◽  
Atom Loss ◽  
Kinetics Of ◽  
Peg 600

Objective: To study the kinetics of periodate oxidation of polyethylene glycol-600 (PEG-600), a familiar non-toxic polymer used in pharmaceutical and other fields of industry. Methods: Reactions were carried out in alkaline medium and measured the kinetics by iodometry. One oxygen atom loss or two electrons transfer was observed per each molecule of periodate i.e., the rate of reaction was measured periodate converts to iodate because the formed iodate species is unable to oxidize the substrate molecules. Results: Based on log (a-x) versus t plots, order w. r. t. oxidant (periodate) is unity. Reactions were found to be independent of substrate (PEG-600) concentration. A decrease in rate with an increase in alkali concentration [OH–] was found and order was inverse fractional. Temperature dependence of reaction rate was studied and then calculated the corresponding Arrhenius parameters. Conclusion: An appropriate rate law was proposed by considering the above experimental results.

scholarly journals Quantitative assessment of lung microstructure in healthy mice using an MR-based 3He lung morphometry technique

2010 ◽  
Vol 109 (6) ◽  
pp. 1592-1599 ◽  
Author(s):  
E. Osmanagic ◽  
A. L. Sukstanskii ◽  
J. D. Quirk ◽  
J. C. Woods ◽  
R. A. Pierce ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Volume Ratio ◽  
Gas Diffusion ◽  
Published Data ◽  
Geometrical Parameters ◽  
Small Animals ◽  
Mean Values ◽  
In Vivo Experiments ◽  
Lung Morphometry

The recently developed technique of lung morphometry using hyperpolarized 3He diffusion magnetic resonance (MR) (Yablonskiy DA, Sukstanskii AL, Woods JC, Gierada DS, Quirk JD, Hogg JC, Cooper JD, Conradi MS. J Appl Physiol 107: 1258–1265, 2009) permits in vivo study of lung microstructure at the alveolar level. Originally proposed for human lungs, it also has the potential to study small animals. The technique relies on theoretical developments in the area of gas diffusion in lungs linking the diffusion attenuated MR signal to the lung microstructure. To adapt this technique to small animals, certain modifications in MR protocol and data analysis are required, reflecting the smaller size of mouse alveoli and acinar airways. This is the subject of the present paper. Herein, we established empirical relationships relating diffusion measurements to geometrical parameters of lung acinar airways with dimensions typical for mice and rats by using simulations of diffusion in the airways. We have also adjusted the MR protocol to acquire data with much shorter diffusion times compared with humans to accommodate the substantially smaller acinar airway length. We apply this technique to study mouse lungs ex vivo. Our MR-based measurements yield mean values of lung surface-to-volume ratio of 670 cm−1, alveolar density of 3,200 per mm3, alveolar depth of 55 μm, and mean chord length of 62 μm, all consistent with published data obtained histologically in mice by unbiased methods. The proposed technique can be used for in vivo experiments, opening a door for longitudinal studies of lung morphometry in mice and other small animals.

Triphase Catalysis Using Silica Gel as Support

2013 ◽  
Vol 11 (1) ◽  
pp. 347-352
Author(s):  
T. Sankarshana ◽  
J. Soujanya ◽  
A. Anil Kumar
Keyword(s):  
Potassium Permanganate ◽  
Silica Gel ◽  
Reaction Rate ◽  
Phase Transfer ◽  
Supported Catalysts ◽  
Batch Reactor ◽  
Kinetic Regime ◽  
Rate Of Reaction ◽  
Potential Applications ◽  
Triphase Catalysis

Abstract The oxidation reaction of 2-ethyl-1-hexanol with potassium permanganate in the presence and absence of silica-gel-supported phase-transfer catalyst (PTC) in triphasic conditions was studied. In a batch reactor, the performance of the solid-supported catalysts was compared with unsupported catalyst and without the catalyst. The effect of speed of agitation, catalyst concentration, potassium permanganate concentration and temperature on reaction rate was studied. The reaction is found to be in the kinetic regime. The rate of reaction with the catalyst immobilised on the silica gel was less compared to the catalyst without immobilisation. Triphase catalysis with supported PTCs has potential applications in the continuous quest for greener industrial practices.

Electrochemically Directed Synthesis of Cobalt(II) and Nickel(II) TCNQF21–/2– Coordination Polymers: Solubility and Substituent Effects in the TCNQFn (n=0, 1, 2, 4) Series of Complexes

2020 ◽  
Vol 73 (12) ◽  
pp. 1197
Author(s):  
Nguyen T. Vo ◽  
Alan M. Bond ◽  
Lisandra L. Martin
Keyword(s):  
Transition Metal ◽  
Coordination Polymers ◽  
Substituent Effects ◽  
Transition Metal Ions ◽  
Published Data ◽  
Electronic Impact ◽  
Diffusion Controlled ◽  
Directed Synthesis ◽  
Two Phases ◽  
Ir And Raman

The reversible diffusion controlled cyclic voltammetry for the reduction of TCNQF­n0/1–/2– (where n=0, 1, 2, 4) changes significantly on addition of Co2+ and Ni2+ transition metal ions (M2+) because the kinetics associated with electrocrystallisation of the resulting coordination polymers [M(TCNQF2)2(H2O)2] and [M(TCNQF2)] are rapid on the voltammetric time scale. The voltammetry of solutions containing M2+ and TCNQF­2 was undertaken in acetonitrile (0.1M Bu4NPF6) at both GC and ITO electrodes. New one electron reduced TCNQF2 materials prepared via electrochemically directed synthesis were shown to have the formula [M(TCNQF2)2(H2O)2], assessed by vibrational (IR and Raman) spectroscopy, elemental analysis and thermogravimetric analysis. The solubility of [Ni(TCNQF2)2(H2O)2] (Ksp=8.29×10−11 M3) was significantly higher than the [Co(TCNQF2)2(H2O)2] (Ksp=1.43×10−11M3). Cyclic voltammetric data suggest the electrocrystallisation of two phases of [Ni(TCNQF2)2(H2O)2] occurs, which is not evident for [Co(TCNQF2)2(H2O)2]. Electrocrystallisation of the highly insoluble [M(TCNQF2)] was achieved at low M2+ and TCNQF2 concentrations. A comparison with published data on the voltammetry of TCNQF­n (n=0, 1, 2 and 4) for the series of TCNQF­n (n=0, 1, 2 and 4) containing M2+ is provided. An assessment of the electronic impact of the fluorine substituent of the underlying redox reactions also is established. Predictions are made for the voltammetric behaviour expected for the other transition metal cations with reduced TCNQFn derivatives.

Review on Bubble Dynamics in Microchannel Heat Sink

2019 ◽  
Author(s):  
Sambhaji T. Kadam ◽  
Ibrahim Hassan ◽  
Ritunesh Kumar ◽  
Aziz Rahman
Keyword(s):  
Bubble Growth ◽  
Bubble Dynamics ◽  
Growth Models ◽  
Flow Boiling ◽  
Nucleation Site ◽  
Bubble Nucleation ◽  
Operating Conditions ◽  
Geometrical Parameters ◽  
Detailed Knowledge ◽  
Diffusion Controlled

Abstract Inception of the boiling, in pool or flow boiling, is the formation of the vapour bubble at active nucleation site. The bubble dynamics plays an important role in the boiling process. It is critical as it unfolds many facets especially when channel size is reduced to submicron. The detailed knowledge of the bubble dynamics is helpful in establishing the thermal and hydraulic flow behaviour in microchannel. In this paper, the bubble dynamics which include bubble nucleation at nucleation site, its growth, departure and motion along the flow in a microchannel are discussed in details. Different models are developed for the critical cavity radius are compiled and observed that they show large variation when compare. The bubble growth models are compiled and concluded that a development of more generalized bubble growth model is necessary to account for the inertia controlled and thermal diffusion controlled regions. The bubble at the nucleation site in a microchannel grows under the influence of various forces such as surface tension, inertia, shear, gravitational and evaporation momentum. Parametric variations of these forces are critically studied and reckoned that the slope of these forces seems to be reduced beyond 500 μm. Eventually, possible impact of the various factors such as operating conditions, geometrical parameters, and thermophysical properties of fluid on bubble dynamics in microchannel has been reported.

ACTION OF HIGH SPEED ELECTRONS ON METHANE, OXYGEN AND CARBON MONOXIDE

1930 ◽  
Vol 3 (3) ◽  
pp. 241-251 ◽  
Author(s):  
J. C. McLennan F.R.S. ◽  
J. V. S. Glass B.A.
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Water Vapor ◽  
Formic Acid ◽  
Total Pressure ◽  
High Speed ◽  
Reaction Rate ◽  
First Order ◽  
Gaseous Products ◽  
Retarding Effect

This paper deals with the action of cathode rays on gases and gas mixtures. Methane, methane-oxygen mixtures, carbon monoxide and carbon monoxide-oxygen mixtures were examined. Methane gave small percentages of hydrogen and ethane. Methane and oxygen mixtures gave as gaseous products, carbon monoxide, carbon dioxide and hydrogen, the only other products being water and formic acid. The relative proportions of the products do not vary widely under a wide variation of conditions.The reaction was found to be of the first order with respect to pressure. The reaction rate increases linearly with the voltage up to a certain value, after which it becomes nearly independent of the voltage.The action of cathode rays on carbon monoxide produces carbon dioxide and a solid brown suboxide which is extremely soluble in water, and its composition corresponds to a formula (C3O)n. If the carbon monoxide is moist, no visible amount of solid or liquid is found and there is less carbon dioxide.Carbon monoxide-oxygen mixtures under the action of cathode rays form carbon dioxide. Presence of water vapor has a retarding effect on the reaction. For mixtures of the same composition the reaction rate is proportional to the total pressure. For dry mixtures the product increases with the carbon monoxide present; when moist it is much less, and independent of the carbon monoxide.

Sign in / Sign up

Export Citation Format

Share Document