Sectional automatic adjustment of catalyst layers in gas and liquid phase reactors

The paper provides a new approach to the high-quality implementation of gas-liquid and catalytic gas-and liquid-phase reactions in displacement reactors. The authors have described the scheme and algorithm for automatic control of the parameters of the catalyst layer. The authors have developed algorithms (mode) for automatic adjustment of the hydrodynamic and thermal modes of the catalytic section and also the principle of automatic adjustment of the system to a gradual or impulse adjusting mode which in case of liquid-phase reaction products results in active dispersion and mutual mixing of reaction products and sharp activation of hydrodynamic and diffusion processes. The article also covers the main requirements for elastically deformable catalytic layers and the advantages of using metalworking machines wastes as adjustable catalyst layers which will have a very significant environmental effect within the recycling and remarketing program.

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ESTIMATION OF LOCAL INHOMOGENEITY OF MULTILAYER NANOSTRUCTURED ZrN/ZrO2 COATING

10.46813/2021-131-106 ◽

2021 ◽

pp. 106-109

Author(s):

T.S. Skoblo ◽

S.P. Romaniuk ◽

Ye.L. Belkin ◽

T.V. Maltsev

Keyword(s):

Structure Formation ◽

Diffusion Processes ◽

Multilayer Coating ◽

Vacuum Arc ◽

New Approach ◽

Reliable Assessment ◽

Vacuum Arc Deposition ◽

Metallographic Images ◽

And Diffusion ◽

Arc Deposition

Multilayer nanostructured ZrN/ZrO2 coatings were applied to increase the operational resistance of various machinery parts by using vacuum-arc deposition in Bulat-type facility. To describe the structure formation, a new approach based on optical-mathematical method for processing metallographic images is proposed. The structure formation of the multilayer coating with an assessment of the degree of its inhomogeneity and diffusion processes between the layers is studied. For a reliable assessment, the changes in the horizontal and vertical directions of the images with the choice of optimal intervals were comparatively analyzed. It has been found that the most stable results are achieved using 20 and 25 dots (pixels).

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Meridional Circulation, Turbulence, and Diffusion Processes in Stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100080477 ◽

1976 ◽

Vol 32 ◽

pp. 109-116 ◽

Cited By ~ 1

Author(s):

S. Vauclair

Keyword(s):

Convection Zone ◽

Diffusion Processes ◽

Meridional Circulation ◽

Diffusion Time ◽

Work In Progress ◽

First Results ◽

Stellar Envelopes ◽

And Diffusion ◽

Turbulence And Diffusion ◽

Hr Diagram

This paper gives the first results of a work in progress, in collaboration with G. Michaud and G. Vauclair. It is a first attempt to compute the effects of meridional circulation and turbulence on diffusion processes in stellar envelopes. Computations have been made for a 2 Mʘstar, which lies in the Am - δ Scuti region of the HR diagram.Let us recall that in Am stars diffusion cannot occur between the two outer convection zones, contrary to what was assumed by Watson (1970, 1971) and Smith (1971), since they are linked by overshooting (Latour, 1972; Toomre et al., 1975). But diffusion may occur at the bottom of the second convection zone. According to Vauclair et al. (1974), the second convection zone, due to He II ionization, disappears after a time equal to the helium diffusion time, and then diffusion may happen at the bottom of the first convection zone, so that the arguments by Watson and Smith are preserved.

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NMR-Study of Structure and Diffusion Processes in Li3N

Le Journal de Physique Colloques ◽

10.1051/jphyscol:1980607 ◽

1980 ◽

Vol 41 (C6) ◽

pp. C6-28-C6-31 ◽

Cited By ~ 2

Author(s):

R. Messer ◽

H. Birli ◽

K. Differt

Keyword(s):

Diffusion Processes ◽

Nmr Study ◽

And Diffusion

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Effect of cluster-gradient architecture of nanostructured topocomposites on features of tribointeraction with heterophased material

10.36652/1813-1336-2020-16-3-130-135 ◽

2020 ◽

pp. 130-135

Author(s):

D.N. Korotaev ◽

K.N. Poleshchenko ◽

E.N. Eremin ◽

E.E. Tarasov

Keyword(s):

Wear Resistance ◽

Titanium Alloy ◽

Energy Dissipation ◽

Phase Structure ◽

Diffusion Processes ◽

Structural Phase ◽

High Wear Resistance ◽

Wear Characteristics ◽

And Diffusion

The wear resistance and wear characteristics of cluster-gradient architecture (CGA) nanostructured topocomposites are studied. The specifics of tribocontact interaction under microcutting conditions is considered. The reasons for retention of high wear resistance of this class of nanostructured topocomposites are studied. The mechanisms of energy dissipation from the tribocontact zone, due to the nanogeometry and the structural-phase structure of CGA topocomposites are analyzed. The role of triboactivated deformation and diffusion processes in providing increased wear resistance of carbide-based topocomposites is shown. They are tested under the conditions of blade processing of heat-resistant titanium alloy.

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Energetic Fuel Droplet Gasification with Liquid-Phase Reaction.

10.21236/ada329877 ◽

1997 ◽

Author(s):

William A. Sirignano ◽

David N. Schiller

Keyword(s):

Liquid Phase ◽

Phase Reaction ◽

Fuel Droplet ◽

Liquid Phase Reaction

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Certain Problems with the Application of Stochastic Diffusion Processes for the Description of Chemical Engineering Phenomena. Diffusional Change of Solid Particle Size

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19960536 ◽

1996 ◽

Vol 61 (4) ◽

pp. 536-563

Author(s):

Vladimír Kudrna ◽

Pavel Hasal

Keyword(s):

Particle Size ◽

Solid Particle ◽

Chemical Engineering ◽

Diffusion Processes ◽

Granular Systems ◽

Size Distributions ◽

Particle Size Distributions ◽

Diffusion Term ◽

Population Balances ◽

And Diffusion

To the description of changes of solid particle size in population, the application was proposed of stochastic differential equations and diffusion equations adequate to them making it possible to express the development of these populations in time. Particular relations were derived for some particle size distributions in flow and batch equipments. It was shown that it is expedient to complement the population balances often used for the description of granular systems by a "diffusion" term making it possible to express the effects of random influences in the growth process and/or particle diminution.

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Effect of Stratification of Cathode Catalyst Layers on Durability of Proton Exchange Membrane Fuel Cells

Energies ◽

10.3390/en14102975 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2975

Author(s):

Zikhona Nondudule ◽

Jessica Chamier ◽

Mahabubur Chowdhury

Keyword(s):

Fuel Cells ◽

Proton Exchange Membrane ◽

Electrochemical Impedance ◽

Catalyst Layer ◽

Cost Effective ◽

Proton Exchange ◽

Membrane Electrode ◽

Potential Cycling ◽

Catalyst Layers ◽

Exchange Membrane

To decrease the cost of fuel cell manufacturing, the amount of platinum (Pt) in the catalyst layer needs to be reduced. In this study, ionomer gradient membrane electrode assemblies (MEAs) were designed to reduce Pt loading without sacrificing performance and lifetime. A two-layer stratification of the cathode was achieved with varying ratios of 28 wt. % ionomer in the inner layer, on the membrane, and 24 wt. % on the outer layer, coated onto the inner layer. To study the MEA performance, the electrochemical surface area (ECSA), polarization curves, and electrochemical impedance spectroscopy (EIS) responses were evaluated under 20, 60, and 100% relative humidity (RH). The stratified MEA Pt loading was reduced by 12% while maintaining commercial equivalent performance. The optimal two-layer design was achieved when the Pt loading ratio between the layers was 1:6 (inner:outer layer). This MEA showed the highest ECSA and performance at 0.65 V with reduced mass transport losses. The integrity of stratified MEAs with lower Pt loading was evaluated with potential cycling and proved more durable than the monolayer MEA equivalent. The higher ionomer loading adjacent to the membrane and the bi-layer interface of the stratified catalyst layer (CL) increased moisture in the cathode CL, decreasing the degradation rate. Using ionomer stratification to decrease the Pt loading in an MEA yielded a better performance compared to the monolayer MEA design. This study, therefore, contributes to the development of more durable, cost-effective MEAs for low-temperature proton exchange membrane fuel cells.

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