Streaming Electric Potential in Pressure-Driven Flows Through Reservoir-Connected Microchannels

2007 ◽  
Vol 129 (10) ◽  
pp. 1346-1357 ◽  
Author(s):  
S. A. Mirbozorgi ◽  
H. Niazmand ◽  
M. Renksizbulut
Keyword(s):  
Zeta Potential ◽  
Electric Potential ◽  
Stokes Equations ◽  
Fundamental Problem ◽  
Electrical Power ◽  
Applied Pressure ◽  
Streaming Potential ◽  
Electrical Current ◽  
Electrokinetic Flow ◽  
Pressure Driven

Electrical power generation employing pressure-driven flows is a fundamental problem in microfluidics. In the present work, analytical and numerical analyses are performed to study the interplaying effects of electrolyte motion with the associated electrical current in a flat microchannel with and without fluid reservoirs. The modified Navier–Stokes equations as well as a Poisson equation for the distribution of electric potential and the Nernst–Planck equations for the distribution of charge densities are solved for the steady flow of a Newtonian liquid. The results show that for a pressure-driven flow, an electric potential is induced due to the motion of charged particles, which increases linearly along the microchannel. This streaming potential generates an opposing conduction current in the core region of the channel as well as in the immediate vicinity of the walls, where the streaming current is negligible. The streaming potential varies in a nonlinear manner with the zeta potential at the walls such that a maximum potential exists at a certain zeta potential. The maximum potential is also observed to increase with both the applied pressure difference and the electric double layer thickness in the range studied. The presence of reservoirs adds significant complexity to this electrokinetic flow.

Electrokinetic Flow and Measure Method in Microfluidic

2013 ◽  
Vol 275-277 ◽  
pp. 649-653 ◽  
Author(s):  
Lei Gong ◽  
Jian Kang Wu ◽  
Bo Chen
Keyword(s):  
Stokes Equations ◽  
Solid Wall ◽  
Streaming Potential ◽  
Navier Stokes ◽  
Electrokinetic Flow ◽  
Navier Stokes Equations ◽  
Electroviscous Effect ◽  
Poisson Boltzmann Equation ◽  
Electrokinetic Flows ◽  
Pressure Driven

An analytical solution for pressure-driven electrokinetic flows in a narrow capillary is presented based on the Poisson–Boltzmann equation for electrical double layer and the Navier–Stokes equations for incompressible viscous fluid. The analytical solutions indicate that pressure-driven flow of an electrolyte solution in microchannel with charged solid wall induces a streaming potential, which is proportional to the flowrate and induces an electroviscous effect on flow. A device for measuring the electrokinetic flow rate and streaming potential is proposed.

Numerical Simulation of Heat Transfer in Mixed Electroosmotic Pressure-Driven Flow in Straight Microchannels

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Amir Shamloo ◽  
Arshia Merdasi ◽  
Parham Vatankhah
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Zeta Potential ◽  
Electric Potential ◽  
Uniform Heat Flux ◽  
Electric Potentials ◽  
Circular Flows ◽  
Flow Through ◽  
Pressure Driven Flow ◽  
Pressure Driven

This paper investigates two-dimensional, time-independent elecroosmotic pressure-driven flow generated by a direct current electric potential with asymmetrical and symmetrical zeta potential distributions along the microchannel walls. Fluid flow through the horizontal microchannel is simulated using a numerical method. Two different cases are proposed to study the effect of electric potential on the flow field. First, negative electric potential is applied on the microchannel walls. In this case, large segments with negative electric potential are initially placed on the first half of the microchannel walls with two different arrangements. Afterward, smaller segments with negative electric potential are placed on the microchannel walls. Next, negative electric potential is replaced by positive electric potential on the microchannel walls in the similar manner. It is shown that applying positive potential on the walls contributes to the localized circular flows within the microchannel. The size of these vortices is also proved to considerably vary with the applied zeta potential magnitude. Finally, the effect of wall zeta potential on heat transfer was studied for all the four types of microchannels by imposing a constant uniform heat flux on the walls. The Nusselt number plots indicate how heat transfer varies along the microchannel walls. The Nusselt number fluctuation can be observed where the positive and negative electric potentials are located.

Electro-Osmotic Flow in Reservoir-Connected Flat Microchannels With Non-Uniform Zeta Potential

2006 ◽  
Vol 128 (6) ◽  
pp. 1133-1143 ◽  
Author(s):  
S. A. Mirbozorgi ◽  
H. Niazmand ◽  
M. Renksizbulut
Keyword(s):  
Zeta Potential ◽  
Electric Potential ◽  
Stokes Equations ◽  
Planck Equation ◽  
Ionic Concentration ◽  
Complex Flow ◽  
Layer Potential ◽  
Osmotic Flow ◽  
Zeta Potentials ◽  
Electro Osmotic Flow

The effects of non-uniform zeta potentials on electro-osmotic flows in flat microchannels have been investigated with particular attention to reservoir effects. The governing equations, which consist of a Laplace equation for the distribution of external electric potential, a Poisson equation for the distribution of electric double layer potential, the Nernst-Planck equation for the distribution of charge density, and modified Navier-Stokes equations for the flow field are solved numerically for an incompressible steady flow of a Newtonian fluid using the finite-volume method. For the validation of the numerical scheme, the key features of an ideal electro-osmotic flow with uniform zeta potential have been compared with analytical solutions for the ionic concentration, electric potential, pressure, and velocity fields. When reservoirs are included in the analysis, an adverse pressure gradient is induced in the channel due to entrance and exit effects even when the reservoirs are at the same pressure. Non-uniform zeta potentials lead to complex flow fields, which are examined in detail.

Electrokinetic Energy Conversion in Conical Nanochannels: Regulation Effect due to Conicity

2019 ◽  
Author(s):  
Fang Qian ◽  
Deng Huang ◽  
Wenyao Zhang ◽  
Wenbo Li ◽  
Qiuwang Wang ◽  
...  
Keyword(s):  
Charge Density ◽  
Energy Conversion ◽  
Surface Charge ◽  
Pressure Difference ◽  
Surface Charge Density ◽  
Electrical Power ◽  
Applied Pressure ◽  
Streaming Potential ◽  
Clean Energy ◽  
Navier Stokes Equation

Abstract Electrokinetic energy conversion being a promising clean energy production technology utilizes the electric double layer (EDL) in a nanochannel to convert hydrodynamic energy to electrical power. The previous research mainly focuses on the electrokinetic energy conversion in straight nanochannels. In this work, we perform a systematic investigation of electrokinetic energy conversion in a conical nanochannel. For this purpose, a multiphysical model consisting of the Planck-Nernst-Poisson equation and Navier-Stokes equation was formulated and solved numerically. Particularly, we discover various regulation effects in the electrokinetic energy conversion in conical nanochannels that the energy conversion characteristics (streaming potential, streaming current and I-V characteristics) are different for a forward pressure difference and a backward pressure difference of the same magnitude. These regulation effects are found to be caused by the conicity of channel. Then the effects of the channel conicity, applied pressure difference and the surface charge density on the performance of electrokinetic energy conversion are discussed in details. It is generally shown that the regulation effects are enhanced by increasing the conicity, pressure difference and surface charge density. The conclusions from this work can serve as important reference and guidelines for the design and operation of electrokinetic energy conversion devices.

How to use alum with cationic dispersed rosin size

TAPPI Journal ◽  
2016 ◽  
Vol 15 (5) ◽  
pp. 331-335 ◽  
Author(s):  
LEBO XU ◽  
JEREMY MYERS ◽  
PETER HART
Keyword(s):  
Zeta Potential ◽  
Colloidal Particles ◽  
Streaming Potential ◽  
Excessive Amount ◽  
Paper Machine ◽  
Optimum Amount ◽  
Potential Measurement ◽  
Streaming Current ◽  
Wide Range ◽  
Laboratory Results

Retention of cationic dispersed rosin size was studied via turbidity measurements on stock filtrate with different alum and dispersed rosin size dosages. Stock charge characteristics were analyzed using both an analysis of charge demand determined via a streaming current detector and an evaluation of zeta potential of the fibers by streaming potential measurement. The results indicated that an optimum amount of alum existed such that good sizing retention was maintained throughout a wide range of dispersed rosin size dosages. However, when an excessive amount of alum was used and fines and colloidal particles were transitioned from anionic to cationic, the cationic size retention was reduced. Laboratory results were confirmed with a paper machine trial. All data suggested that a stock charge study was necessary to identify optimal alum dosage for a cationic dispersed rosin sizing program.

scholarly journals Effect of Applied Pressure on the Electrical Resistance of Carbon Nanotube Fibers

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2106
Author(s):  
Chris J. Barnett ◽  
James D. McGettrick ◽  
Varun Shenoy Gangoli ◽  
Ewa Kazimierska ◽  
Alvin Orbaek White ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electrical Resistance ◽  
Copper Wire ◽  
Applied Pressure ◽  
Radial Strain ◽  
Electrical Current ◽  
Electrical Contacts ◽  
Electrical Performance ◽  
Macro Scale ◽  
Carbon Nanotube Fibers

Carbon nanotubes (CNTs) can be spun into fibers as potential lightweight replacements for copper in electrical current transmission since lightweight CNT fibers weigh <1/6th that of an equivalently dimensioned copper wire. Experimentally, it has been shown that the electrical resistance of CNT fibers increases with longitudinal strain; however, although fibers may be under radial strain when they are compressed during crimping at contacts for use in electrical current transport, there has been no study of this relationship. Herein, we apply radial stress at the contact to a CNT fiber on both the nano- and macro-scale and measure the changes in fiber and contact resistance. We observed an increase in resistance with increasing pressure on the nanoscale as well as initially on the macro scale, which we attribute to the decreasing of axial CNT…CNT contacts. On the macro scale, the resistance then decreases with increased pressure, which we attribute to improved radial contact due to the closing of voids within the fiber bundle. X-ray photoelectron spectroscopy (XPS) and UV photoelectron spectroscopy (UPS) show that applied pressure on the fiber can damage the π–π bonding, which could also contribute to the increased resistance. As such, care must be taken when applying radial strain on CNT fibers in applications, including crimping for electrical contacts, lest they operate in an unfavorable regime with worse electrical performance.

Effect of clay colloids on the zeta potential of Fe/Al oxide-coated quartz: a streaming potential study

2016 ◽  
Vol 16 (12) ◽  
pp. 2676-2686 ◽  
Author(s):  
Zhong-yi Li ◽  
Ren-kou Xu ◽  
Jiu-yu Li ◽  
Zhi-neng Hong
Keyword(s):  
Zeta Potential ◽  
Streaming Potential ◽  
Potential Study ◽  
Al Oxide

The Determination of Electrokinetic Coupling-Coefficient and Zeta Potential of Rock Samples by Electrokinetic Measurements

2012 ◽  
Vol 516-517 ◽  
pp. 1870-1873 ◽  
Author(s):  
Jun Wang ◽  
Heng Shan Hu
Keyword(s):  
Zeta Potential ◽  
Coupling Coefficient ◽  
Streaming Potential ◽  
Potential Method ◽  
Surface Conductivity ◽  
Reliable Estimate ◽  
Surface Conductance ◽  
Streaming Current ◽  
Low Concentrations

The electrokinetic effects are important in the understanding of electric properties in porous medium. In this study, the streaming potential and streaming current of saturated samples are measured at different concentrations, then three methods are applied to obtain the zeta-potential and electrokinetic coupling coefficient. The study shows that the results obtained from streaming potential and streaming current methods agree well with each other, but the results obtained from simplified streaming potential method become seriously inaccurate at low concentrations due to the influence of surface conductance. This experimental study also provides a reliable estimate of the surface conductivity and its contribution to zeta-potential at given concentrations.

Combustion joining of refractory materials: Carbon–carbon composites

2008 ◽  
Vol 23 (1) ◽  
pp. 160-169 ◽  
Author(s):  
Jeremiah D.E. White ◽  
Allen H. Simpson ◽  
Alexander S. Shteinberg ◽  
Alexander S. Mukasyan
Keyword(s):  
Applied Pressure ◽  
Electrical Current ◽  
Carbon Composite ◽  
Carbon Composites ◽  
Refractory Materials ◽  
Temperature Combustion ◽  
Reaction Media ◽  
High Temperature Combustion ◽  
Media Layer ◽  
Reactive Media

Refractory materials such as carbon possess properties that make joining them difficult. In this work, bonding of a carbon–carbon composite is achieved by employing self-sustained, oxygen-free, high-temperature combustion reactions. The effects of several parameters, such as the composition of the reaction media, and the values of the applied current and pressure, on the mechanical strength of the joint were investigated. It was found that the C–C composite possesses a high activity with the reactive media layer, the level of electrical current used to initiate the reaction and the applied pressure do not need to be excessive to obtain a strong joint. Some aspects of the joining mechanism are discussed in detail.

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