Electrochemical reaction with RedOx electrolyte in toroidal conduits in the presence of natural convection

Qian, Shizhi; Chen, Zongyuan; Wang, Jing; Bau, Haim H.

doi:10.1016/j.ijheatmasstransfer.2006.04.024

Cited by 19 publications

(12 citation statements)

References 25 publications

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“…We emphasize, however, that body forces due to density variations may, on occasion, play a significant role even when device dimensions are relatively small. See, for example, Qian et al (2006).…”

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confidence: 99%

When MHD-based microfluidics is equivalent to pressure-driven flow

Qin

Bau

2010

Microfluid Nanofluid

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Magnetohydrodynamics (MHD) provides a convenient, programmable means for propelling liquids and controlling fluid flow in microfluidic devices without a need for mechanical pumps and valves. When the magnetic field is uniform and the electric field in the electrolyte solution is confined to a plane that is perpendicular to the direction of the magnetic field, the Lorentz body force is irrotational and one can define a "Lorentz" potential. Since the MHD-induced flow field under these circumstances is identical to that of pressure-driven flow, one can utilize the large available body of knowledge about pressure-driven flows to predict MHD flows and infer MHD flow patterns. In this note, we prove the equivalence between MHD flows and pressure-driven flows under certain conditions other than flow in straight conduits with rectangular crosssections. We determine the velocity profile and the efficiency of MHD pumps, accounting for current transport in the electrolyte solutions. Then, we demonstrate how data available for pressure driven flow can be utilized to study various MHD flows, in particular, in a conduit patterned with pillars such as may be useful for liquid chromatography and chemical reactors. Additionally, we examine the effect of interior obstacles on the electric current flow in the conduit and show the existence of a particular pillar geometry that maximizes the current. solution is confined to a plane that is perpendicular to the direction of the magnetic field, the Lorentz body force is irrotational and one can define a "Lorentz" potential. Since the MHDinduced flow field under these circumstances is identical to that of pressure-driven flow, one can utilize the large available body of knowledge about pressure-driven flows to predict MHD flows and infer MHD flow patterns. In this note, we prove the equivalence between MHD flows and pressure-driven flows under certain conditions other than flow in straight conduits with rectangular cross-sections. We determine the velocity profile and the efficiency of MHD pumps, accounting for current transport in the electrolyte solutions. Then, we demonstrate how data available for pressure driven flow can be utilized to study various MHD flows, in particular, in a conduit patterned with pillars such as may be useful for liquid chromatography and chemical reactors. Additionally, we examine the effect of interior obstacles on the electric current flow in the conduit and show the existence of a particular pillar geometry that maximizes the current.

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confidence: 99%

When MHD-based microfluidics is equivalent to pressure-driven flow

Qin

Bau

2010

Microfluid Nanofluid

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“…However, the cathodic peak, around 0.0 V, is irregular and changes during the cycles. The anodic peak at 0.2 V is well defined and remains unchanged during the cycles, and thus can be The ionic mass transport is governed by convection, diffusion, and migration [66,68,70]. With the supporting electrolyte, the contribution of the migration to the ionic mass transport is negligible.…”

Section: Resultsmentioning

confidence: 99%

“…In the absence of a magnetic field (i.e., B = 0), only diffusion contributes to the ionic mass transport if we neglect the natural convection induced by the electrochemical reactions [70]. In the presence of a magnetic field, the interactions between the current transmitted through the electrolyte solution and the magnetic field induce Lorentz forces and consequently MHD convection [61,70]; thus both convection and diffusion contribute to the ionic mass transport.…”

Section: Resultsmentioning

confidence: 99%

“…In the presence of a magnetic field, the interactions between the current transmitted through the electrolyte solution and the magnetic field induce Lorentz forces and consequently MHD convection [61,70]; thus both convection and diffusion contribute to the ionic mass transport. The induced MHD convection plays a significant role in the electrochemical system even though the dimensions of the electrochemical cell are quite small [63][64][65]71].…”

Section: Resultsmentioning

confidence: 99%

“…The MHD boost on the SPR angle shifts thus increases as the concentration of Hg 2+ ions increases, and seems to saturate in micromolar order. The current transmitted through the solution increases with the concentration of the mercury (II) ions [68,70], which leads to higher Lorentz force and stronger fluid motion to enhance the ionic mass transport [70,72].…”

Section: Resultsmentioning

confidence: 99%

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