Electrochemical engineering, comparison

Before the economic-financial feasibility study which is (Ml the basis of the final decision to implement a process, it is necessary to evaluate the technicaJ/technological viability of the possible routes. In electrochemical engineering practice, it is common to ccMisider a set of figures of merit [32] and to establish comparisons with the same parameters of competitive alternatives. Unfoitunately, the literature ccMiceming the above mentioned matters on the employment of three dimensional electrodes is scarce and out-dated. 

Figure 13 Conceptual comparison between heat engines and electrochemical engines.

The results are very encouraging, and show that, as expected, the power consumption of the electrochemically promoted unit, which is promotional to A 1, is negligible in comparison to the Diesel engine power output (Table 12.3). This work demonstrates the great potential of electrochemical promotion for practical applications. The first fifty Dinex units were sold in 2001. 

In practice the situation is less favorable due to losses associated with overpotentials in the cell and the resistance of the membrane. Overpotential is an electrochemical term that, basically, can be seen as the usual potential energy barriers for the various steps of the reactions. Therefore, the practical efficiency of a fuel cell is around 40-60 %. For comparison, the Carnot efficiency of a modern turbine used to generate electricity is of order of 50 %. It is important to realize, though, that the efficiency of Carnot engines is in practice limited by thermodynamics, while that of fuel cells is largely set by material properties, which may be improved. 

In the paper from V. Matveyev of the Ukrainian State University of Chemical Engineering, an examination of the role of conductive carbon additives in a composite porous electrode is conducted. A model for calculation of the local electrochemical characteristics of an electrode is presented. A comparison on the polarization of the electrode as a function of the redox state of the electroactive species is emphasized in the model. The electrochemical reaction of chloranil (tetrachlorobenzoquinone) was measured and results compare favorably to calculations derived from the model. 

The comparison between measured and calculated data proves that the potential model can be a useful engineering device to design electrochemical systems. 

Despite the potential of the BEM to reduce the dimensionahty of the numerical solution and provide a direct measure of the interfadal flux, it has been poorly exploited by workers in the electrochemical field in comparison with the FDM and the FEM. By comparison, heat and mass transfer have been widely treated using the BEM in the engineering literature [148-151]. In 1984, the BEM was employed to calculate the primary current distribution during an electropolymerization reaction [152], the potential of the BEM for apphcations to irregular geometries was also noted. Hume and coworkers [153] used the approach to analyze mass transport effects of electrode-position through polymeric masks. 

The most Important engineering parameter Is the space-time yield parameter which defines the electrode/cell performance. The Importance of this term Is that It can be normalized thus allowing direct comparison both between different reactor designs and between electrochemical and non-electrochemical processes. The space-time yield term Is defined for an electrode as ... 

In recent years, ionic liquids (ILs) have attracted much attention [5-8]. In comparison with the conventional solvents (usually water and organic solvents), ILs have some unique properties. For example, ILs are an interesting class of tunable and designable solvents with essentially zero volatility, wide electrochemical window, nonflammability, high thermal stability, and wide liquid range. These make them unique for uses and applications in the areas of chemistry and chemical engineering. 

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