Dynamic electrodes three-dimensional

Three-dimensional electrodes are configured as static or solid electrodes (porous or packed bed), or as dynamic or fluid bed electrodes (fluidized bed and moving bed), cf. Table 6. 

Cells with three-dimensional electrodes providing enlarged specific electrode area and improved mass transport due to the specific fluid dynamics inside the three-dimensional structure are, for example, the porous flow-through cell [68], the RETEC (RETEC is a trademark of ELTECH Systems Inc., Cardon, Ohio) cell [15], the packed-bed cell [69-71],... 

From a mathematical point of view, the treatment of spatiotemporal dynamics on disk electrodes is considerably more difficult than that of the (infinitesimally thin) ring electrode. Of course, on the one hand this is due to the additional spatial dimension. Since the direction into the electrolyte has also to be considered, the problem is spatially three-dimensional. However, even if this complication is neglected by considering, in a first step, only the radial and axial directions (i.e., neglecting possible structures in the azimuthal direction), solving the resulting partial differential equations is still a challenging task. This is due to the mixed boundary... 

There is vast literature detailing the use of different electrochemical reactors used for metal removal [2, 6]. The main types of electrochemical reactors can be classified first according to the kind of electrode as two or three-dimensional. The second classification considers the movement of the electroactive material with relation to a fixed referential. Thus the electrodes can be classified as static or mobile. Figure 1 shows the major electrode classifications according to geometry and fluid dynamics [1]. 

Preparatory work for the steps in the scaling up of the membrane reactors has been presented in the previous sections. Now, to maintain the similarity of the membrane reactors between the laboratory and pilot plant, dimensional analysis with a number of dimensionless numbers is introduced in the scaling-up process. Traditionally, the scaling-up of hydrodynamic systems is performed with the aid of dimensionless parameters, which must be kept equal at all scales to be hydrodynamically similar. Dimensional analysis allows one to reduce the number of variables that have to be taken into accoimt for mass transfer determination. For mass transfer under forced convection, there are at least three dimensionless groups the Sherwood number, Sh, which contains the mass transfer coefficient the Reynolds number. Re, which contains the flow velocity and defines the flow condition (laminar/turbulent) and the Schmidt number, Sc, which characterizes the diffusive and viscous properties of the respective fluid and describes the relative extension of the fluid-dynamic and concentration boundary layer. The dependence of Sh on Re, Sc, the characteristic length, Dq/L, and D /L can be described in the form of the power series as shown in Eqn (14.38), in which Dc/a is the gap between cathode and anode Dw/C is gap between reactor wall and cathode, and L is the length of the electrode (Pak. Chung, Ju, 2001) ... 

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