Two-dimensional space charged limiting current density of a long-pulse electron flow in drift space

Author(s):  
Y. L. Liu ◽  
S. H. Chen ◽  
W. S. Koh
Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1397
Author(s):  
Andreas Gross ◽  
Arthur Morvezen ◽  
Pedro Castillo Gomez ◽  
Xuesong Xu ◽  
Pei Xu

Ion-selective membranes are an important component of electrodialysis stacks for desalination. Manufacturing imperfections or slight inhomogeneity of the material can lead to minute membrane surface imperfections. Two-dimensional solutions of the coupled Poisson–Nernst–Planck and Navier–Stokes equations were sought for a perfectly smooth membrane and for membranes with well-defined small-amplitude harmonic surface roughness. The simulations were carried out with the validated rheoEFoam solver by Pimenta and Alves. In the overlimiting regime, the electric field is strong enough for an electrokinetic instability to occur. The instability leads to disturbance growth and the formation of electro-convection cells, which strongly increase the current density. The present simulations show that with an increasing ion concentration and applied voltage, the instability becomes stronger and the overlimiting regime is reached earlier. The limiting current density shows a noticeable dependence on the wavelength of the surface roughness. When the wavelength of the surface roughness is incommensurate with the wavelength of the naturally occurring instability, the limiting current density is increased. Since production membranes will always have some degree of surface roughness, this suggests that membrane surface treatments which favor certain wavelengths may have an effect on the overall membrane performance.


2021 ◽  
Vol 8 (4) ◽  
pp. 712-718
Author(s):  
Xiankang Zhong ◽  
Matthias Schulz (née Uebel) ◽  
Chun‐Hung Wu ◽  
Martin Rabe ◽  
Andreas Erbe ◽  
...  

1991 ◽  
Vol 17 (5) ◽  
pp. 1006-1011 ◽  
Author(s):  
Yasunobu Hiraoka ◽  
Akira Tomizawa ◽  
Tatsuki Oguchi ◽  
Etsuko Suzuki ◽  
Masanobu Koutake

2015 ◽  
Vol 1110 ◽  
pp. 179-184
Author(s):  
Kyung Man Moon ◽  
Dong Hyun Park ◽  
Yun Hae Kim ◽  
Tae Sil Baek

Recently, anti-fouling paints which does not include the poison components such as tin (Sn) free, copper (Cu) free have been increasingly developed in order to decrease the contamination of marine environment. Moreover, the wear ratios of these anti-fouling paints are very important problem to prolong their life time in economical and environmental point of view. In this study, four types of anti-fouling paints as self-polishing type were investigated on the relationship between their polarization characteristics and wear ratios. Relationship between wear ratio and variation ratio of polarization resistance measured in corrosion potential was not well matched with each other. However, there was a good agreement between the wear ratio and variation ratio of diffusion limiting current density, for example, the higher or the lower variation ratio of diffusion limiting current density, wear ratio also increased or decreased respectively. Consequently, it is suggested that we can qualitatively expect the life time and wear degree of anti-fouling paint by only measuring the polarization characteristics before the wear test is practically performed in the field.Keywords: Anti-fouling paint, Self-polishing type, Polarization characteristics, Wear ratio, Diffusion limiting current density, Corrosion Potential


2001 ◽  
Vol 64 (1) ◽  
Author(s):  
L. K. Ang ◽  
T. J. T. Kwan ◽  
Y. Y. Lau

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