scholarly journals The effect of turbulence on mass transfer rates between inertial polydisperse particles and fluid

2019 ◽  
Vol 874 ◽  
pp. 1147-1168 ◽  
Author(s):  
Ewa Karchniwy ◽  
Adam Klimanek ◽  
Nils Erland L. Haugen
Keyword(s):  
Mass Transfer ◽  
Time Scale ◽  
Transfer Rate ◽  
Particle System ◽  
Mass Transfer Rate ◽  
Stokes Number ◽  
Flow Time ◽  
Inertial Particles ◽  
Integral Scale ◽  
Order Of Magnitude

The current work investigates how turbulence affects the mass transfer rate between inertial particles and fluid in a dilute, polydisperse particle system. Direct numerical simulations are performed in which all scales of turbulence are fully resolved and particles are represented in a Lagrangian reference frame. The results show that, similarly to a monodisperse system, the mass transfer rate between particles and fluid decreases as a result of particle clustering. This occurs when the flow time scale (based on the turbulence integral scale) is long relative to the chemical time scale, and is strongest when the particle time scale is one order of magnitude smaller than the flow time scale (i.e. the Stokes number is around 0.1). It is also found that for larger solid mass fractions, the clustering of the heavier particles is enhanced by the effect of drag force from the particles on the fluid (momentum back-reactions or two-way coupling). In particular, when two-way coupling is accounted for, locations of particles of different sizes are much more correlated, which leads to a stronger effect of clustering, and thus a greater reduction of the particle–fluid mass transfer rate.

scholarly journals Minimum Orbital Period of Cataclysmic Variables

1979 ◽  
Vol 53 ◽  
pp. 504-504
Author(s):  
B. Paczynski ◽  
W. Krzeminski
Keyword(s):  
Mass Transfer ◽  
Angular Momentum ◽  
Orbital Period ◽  
Time Scale ◽  
Transfer Rate ◽  
Main Sequence ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
Transfer Rates ◽  
Angular Momentum Loss

The shortest known orbital period of a cataclysmic binary with a hydrogen dwarf secondary filling its Roche lobe is about 80 minutes. Theoretically the shortest possible orbital period for such a system is less than 60 minutes. We tried to explain why the periods shorter than 80 minutes are not observed. We estimated the time scale of angular momentum loss of a cataclysmic binary and the resulting mass transfer rate. The minimum orbital period for a given Ṁ is obtained during the transition of the secondary from the Main Sequence onto the Degenerate Dwarf Sequence. Pmin ∝ Ṁ½ Therefore, only those systems can reach low P for which Ṁ is small. This explains why among the shortest period cataclysmic variables there are no novae: presumably their mass transfer rates are too large. It also indicates that “polars” (AM Her-type stars) and SU UMa-type stars should have low Ṁ.

scholarly journals The effect of turbulence on mass transfer rates of small inertial particles with surface reactions

2017 ◽  
Vol 836 ◽  
pp. 932-951 ◽  
Author(s):  
Nils Erland L. Haugen ◽  
Jonas Krüger ◽  
Dhrubaditya Mitra ◽  
Terese Løvås
Keyword(s):  
Mass Transfer ◽  
Gas Phase ◽  
Transfer Rate ◽  
Relative Velocity ◽  
Surface Reactions ◽  
Mass Transfer Rate ◽  
Navier Stokes ◽  
Inertial Particles ◽  
Dense Particle ◽  
Simulation Tools

The effect of turbulence on the mass transfer between a fluid and embedded small heavy inertial particles that experience surface reactions is studied. For simplicity, the surface reaction, which takes place when a gas phase reactant is converted to a gas phase product at the external surface of the particles, is unimolar and isothermal. Two effects are identified. The first effect is due to the relative velocity between the fluid and the particles, and a model for the relative velocity is presented. The second effect is due to the clustering of particles, where the mass transfer rate is inhibited due to the rapid depletion of the consumed species inside the dense particle clusters. This last effect is relevant for large Damköhler numbers, where the Damköhler number is defined as the ratio of the turbulent and chemical time scales, and it may totally control the mass transfer rate for Damköhler numbers larger than unity. A model that describes how this effect should be incorporated into existing simulation tools that utilize the Reynolds averaged Navier–Stokes approach is presented.

Free Convective Mass Transfer at Isosceles Triangular Surfaces of Varying Inclination

2003 ◽  
Vol 68 (11) ◽  
pp. 2080-2092 ◽  
Author(s):  
Martin Keppert ◽  
Josef Krýsa ◽  
Anthony A. Wragg
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Mass Transfer Process ◽  
Sulfate Solution ◽  
Convective Mass Transfer ◽  
Varying Length ◽  
Inclined Surface ◽  
Vertical Case ◽  
Limiting Diffusion Current

The limiting diffusion current technique was used for investigation of free convective mass transfer at down-pointing up-facing isosceles triangular surfaces of varying length and inclination. As the mass transfer process, copper deposition from acidified copper(II) sulfate solution was used. It was found that the mass transfer rate increases with inclination from the vertical to the horizontal position and decreases with length of inclined surface. Correlation equations for 7 angles from 0 to 90° were found. The exponent in the ShL-RaL correlation ranged from 0.247 for the vertical case, indicating laminar flow, to 0.32 for inclinations of 60 to 90°, indicating mixed or turbulent flow. The general correlation ShL = 0.358(RaL sin θ)0.30 for the RaL sin θ range from 7 × 106 to 2 × 1011 and inclination range from 15 to 90° was obtained.

Distributed mass transfer rate for modelling the leaching of porous granular materials containing soluble pollutants

2000 ◽  
Vol 55 (7) ◽  
pp. 1257-1267 ◽  
Author(s):  
Tiruta-Barna Ligia ◽  
Barna Radu ◽  
Moszkowicz Pierre ◽  
Bae Hae-Ryong
Keyword(s):  
Mass Transfer ◽  
Granular Materials ◽  
Transfer Rate ◽  
Mass Transfer Rate

Enhancement of formic acid production from CO2 in formate dehydrogenase reaction using nanoparticles

RSC Advances ◽  
2016 ◽  
Vol 6 (111) ◽  
pp. 109978-109982 ◽  
Author(s):  
Young-Kee Kim ◽  
Sung-Yeob Lee ◽  
Byung-Keun Oh
Keyword(s):  
Mass Transfer ◽  
Formic Acid ◽  
Acid Production ◽  
Transfer Rate ◽  
Formate Dehydrogenase ◽  
Mass Transfer Rate ◽  
Liquid Mass ◽  
Dehydrogenase Reaction ◽  
Liquid Mass Transfer ◽  
Mesoporous Nanoparticles

In an enzyme process using a gas substrate, the enhanced gas liquid mass transfer rate of the gas substrate by methyl-functionalized mesoporous nanoparticles could improve the productivity.

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