Electrode shape effect

With four-electrode measurements effected from the surface, an average soil resistivity over a larger area is obtained. The resistivity of a relatively localized layer of earth or pocket of clay can only be accurately measured by using a spike electrode. Figure 3-18 gives dimensions and shape factors, Fg, for various electrodes. 

Numerous studies of NO removal in DBD have been carried out [20-36], The effect of electrode shape, discharge gap length, discharge polarity, gas composition and flow rate, and operation temperature on NO conversion will be considered. 

Takaki, K., Shimizu, M., Mukaigawa, S. et al. (2004) Effect of Electrode Shape in Dielectric Barrier Discharge Plasma Reactor for NOx Removal, IEEE Trans. PI. Sci. 32, 32-8. 

Edge effects at rotating disc electrodes caused by using different electrode shapes have been discussed by Blurton and Riddiford [111]. Their conclusion was that a bell-shaped mantle was best, although cylindrical electrodes, which are widely used, are perfectly sufficient in... 

Temperature variations. Essentially all kinetic phenomena are temperature dependent ion diffusion (in both electrolyte and active materials), electron transfer, desolvation, adsorption, etc. Additionally, thermodynamic equilibrium constants are temperature dependent, so any temperature variations within the cell will produce uneven plating and stripping, electrode shape change effects and uneven utilization again leading to compromised performance. 

The simultaneous measurement of heat transfer and electrochemical quantities has been described in the literature [16-18]. Tubular and disc-shaped specimens proved to be suitable although difficulties arose in obtaining uniform heat transfer on the surface. For example, it was found that crevice corrosion can occur in the side insulation of disc electrodes. This effect may be attributed in some cases to the decreased heat flux and therefore higher surface temperature on the outer circumference of the specimen. 

Partially to check the electrode shape change algorithm and partially because the edge effect in itself is a fascinating phenomenon, we decided to perform experiments. For that purpose, the cell in which the current distributions were measured (section 3.6) was adapted. Also the electrolyte was slightly changed. 

Effect of electrode shape on wall profile by disk microtool [7]. 

As shown in Fig. 18, the Pd/CPAA electrode is quite active for the oxidation of all the alcohols investigated. The better performance of the Pd/CPAA electrode as compared to the Pd/C electrode has been attributed to the improved mass transport of the alcohols across the micropores and mesopores bimodal stracmre of the material supporting the Pd catalyst on the former electrode. This effect is actually highlighted by the parabolic shape of the... 

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