Modeling and simulation of PM2.5 collection efficiency in a wire-plate ESP subjected to magnetic field and diffusion charging

2014 ◽  
Vol 34 (3) ◽  
pp. 697-702 ◽  
Author(s):  
Jianping Zhang ◽  
Dacheng Xu ◽  
Jianxing Ren ◽  
Helen Wu ◽  
Weiguo Pan
Keyword(s):  
Magnetic Field ◽  
Modeling And Simulation ◽  
Collection Efficiency ◽  
Diffusion Charging ◽  
And Diffusion

Fast (non-)diffusive Quasi-Geostrophic Magneto-Coriolis Modes in the Earth's core

2021 ◽  
Author(s):  
Felix Gerick ◽  
Dominique Jault ◽  
Jerome Noir
Keyword(s):  
Magnetic Field ◽  
Magnetic Energy ◽  
Three Dimensional ◽  
Outer Core ◽  
Equatorial Region ◽  
Earth’S Core ◽  
Earth's Core ◽  
Strong Focusing ◽  
Geomagnetic Observations ◽  
And Diffusion

<p> Fast changes of Earth's magnetic field could be explained by inviscid and diffusion-less quasi-geostrophic (QG) Magneto-Coriolis modes. We present a hybrid QG model with columnar flows and three-dimensional magnetic fields and find modes with periods of a few years at parameters relevant to Earth's core. These fast Magneto-Coriolis modes show strong focusing of their kinetic and magnetic energy in the equatorial region, while maintaining a relatively large spatial structure along the azimuthal direction. Their properties agree with some of the observations and inferred core flows. We find additionally, in contrast to what has been assumed previously, that these modes are not affected significantly by magnetic diffusion. The model opens a new way of inverting geomagnetic observations to the flow and magnetic field deep within the Earth's outer core.</p>

Influence of Applied Magnetic Field on a Wire-Plate Electrostatic Precipitators Under Multi-Field Coupling

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Jian-Ping Zhang ◽  
Yong-Xia Dai ◽  
Jiong-Lei Wu ◽  
Jian-Xing Ren ◽  
Helen Wu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Fine Particles ◽  
Collection Efficiency ◽  
Mathematic Model ◽  
Average Diameter ◽  
Dust Particles ◽  
Particle Dynamic ◽  
Electrostatic Precipitators ◽  
The Magnetic Field

The aim of this work is to find an effective method to improve the collection efficiency of electrostatic precipitators (ESPs). A mathematic model of an ESP subjected to the external magnetic field was proposed. The model considered the coupled effects between the gas flow field, particle dynamic field and electromagnetic field. Particles following a Rosin-Rammler distribution were simulated under various conditions and the influence of the magnetic field density on the capture of fine particles was investigated. The collection efficiency and the escaped particle size distribution under different applied magnetic field intensities were discussed. Particle trajectories inside the ESP under aerodynamic and electromagnetic forces were also analyzed. Numerical results indicate that the collection efficiency increases with the increase of applied magnetic field. It was also found that a stronger applied magnetic field results in a larger particle deflection towards the dust collection plates. Furthermore, the average diameter of escaping particles decreases and the dispersion of dust particles with different sizes increases with the increasingly applied magnetic field. Finally, the average diameter decreases almost linearly with the magnetic field until it drops to a certain value. The model proposed in this work is able to obtain important information on the particle collection phenomena inside an industrial ESP under the applied magnetic field.

Spin relaxation due to magnetic-field inhomogeneities: Quartic dependence and diffusion-constant measurements

1990 ◽  
Vol 41 (7) ◽  
pp. 3672-3688 ◽  
Author(s):  
K. C. Hasson ◽  
G. D. Cates ◽  
K. Lerman ◽  
P. Bogorad ◽  
W. Happer
Keyword(s):  
Magnetic Field ◽  
Spin Relaxation ◽  
Diffusion Constant ◽  
And Diffusion

Heat and Diffusion Fluxes in a Multicomponent Ionized Gas in a Magnetic Field

1969 ◽  
Vol 24 (6) ◽  
pp. 967-976
Author(s):  
R. S. Devoto
Keyword(s):  
Magnetic Field ◽  
Heat Flux ◽  
Thermal Diffusion ◽  
Diffusion Flux ◽  
Momentum Equation ◽  
Ionized Gas ◽  
Burnett Method ◽  
And Diffusion ◽  
Monatomic Gas

Ordinary and thermal diffusion as well as heat flux in a dilute, ionized, multicomponent monoatomic gas in a magnetic field are considered with the Chapman-Enskog-Burnett method. It is shown how, with certain modifications, the usual expressions for the properties of an un-ionized monatomic gas may be applied to this case. The expression for the diffusion flux is compared with the momentum equation suggested by Schliiter.

Determination of Residual Oil Saturation by Use of Enhanced Diffusion

1999 ◽  
Vol 2 (03) ◽  
pp. 303-309 ◽  
Author(s):  
Ridvan Akkurt ◽  
Dave Marschall ◽  
R.Y. Eyvazzadeh ◽  
J.S. Gardner ◽  
Duncan Mardon ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Surface Relaxation ◽  
Diffusion Method ◽  
Residual Oil ◽  
Oil Saturation ◽  
Residual Oil Saturation ◽  
Enhanced Diffusion ◽  
Two Phases ◽  
And Diffusion

Summary The enhanced diffusion method (EDM) exploits the diffusion contrast between oil and water separating their respective nuclear magnetic resonance (NMR) signals. Unlike standard NMR logs acquired with short interecho time (TE), measurements, EDM data are acquired using long T E accentuating diffusion. Fundamentally the EDM establishes an absolute upper bound for the T2 of water, thus any T2's greater than this limit unambiguously indicates that oil is present. The EDM's best application is with intermediate viscosity oils (approximately 1 to 50 cp) complementing other NMR hydrocarbon-typing applications designed for lighter hydrocarbons (i.e., the differential spectrum method). While expanding the viscosity range of NMR hydrocarbon-typing applications, the EDM also provides a method by which to determine residual oil saturation (ROS), which is the main focus of this article. The potential use of NMR as a direct indicator of hydrocarbon saturation via techniques such as the differential spectrum method (DSM) has generated significant interest in the petrophysical community in recent years. Although originally developed for applications involving natural gas, the DSM has also been used successfully in light hydrocarbon environments. However, success has been limited to the low end of the viscosity spectrum because of the T1 separation requirements between the brine and hydrocarbon phases. The T1 separation requirement imposed on diffusion applications in higher viscosity oils can be eliminated by using the EDM, where diffusion is turned into the dominant relaxation mode for the wetting brine phase. Given that brine is more diffusive than the hydrocarbons, the longest apparent T2 from the brine phase can be made short enough to cause separation between the two phases in T2 space, thereby eliminating the need for T1 separation. Wait time manipulation can then be used to quantify hydrocarbon volumes when the two phases are separated in the T2 domain. In this article we focus on determination of the residual oil saturation using the EDM, while also providing guidelines for job screening and acquisition parameter selection. Several case histories that are provided are used to illustrate the basic concepts and different methodologies available. Introduction The enhanced diffusion method is a new method developed to distinguish oil and water NMR signals in a gradient magnetic field by exploiting the diffusion contrast between the two fluids. The method is applicable for moderate oil viscosities, approximately in the ~1 to ~50 cp range. The major objective of this article is to discuss EDM signal processing techniques for residual oil saturation, and the reader is referred to existing literature1 for a detailed discussion regarding the petrophysical concepts and related laboratory measurements of the EDM. A secondary objective is to provide guidelines that can be used to screen potential EDM applications and to determine optimal acquisition parameters. Within the context used in this article, residual oil saturation is defined as the oil saturation in the flushed zone after drilling fluid invasion, and the terms residual and flushed zone oil saturation are used interchangeably. Theory The basic concept of the EDM is to turn diffusion into an effective transverse relaxation mechanism while minimizing the dominance of surface relaxation by acquiring NMR logs at long interecho times. Three different mechanisms, which operate in parallel, contribute to the overall apparent relaxation rate of water in porous media: $$1/T {2AW}=1/T {2BW}+1/T {2SW}+1/T {2DW},\eqno ({\rm 1})$$ where the subscript W stands for water, and A, B, S, D denote apparent, bulk, surface-induced, and diffusion-induced mechanisms, respectively. The surface and diffusion induced relaxation rates are given by $$1/T {2SW}=\rho {2}S/V,\eqno ({\rm 2})$$$$1/T {2DW}=((\gamma GT {E})^{2}D {0W})/12,\eqno ({\rm 3})$$ where ?2 is surface relaxivity, S/V is the surface-to-volume ratio, ? is the gyromagnetic ratio, G is the magnetic field gradient, TE is the interecho time, and D0W is the self-diffusion coefficient of water. In standard logging modes using short TE surface relaxation dominates since (1) T2BW is very long, especially at elevated temperatures, and (2) T2BW is also very long because of the short TE values used, despite large magnetic field gradients of the logging tools.

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