Cell voltage, increasing

Section 8, the cell voltage increases with cell pressure. Thus, operating with an elevated pressure will yield increased power and efficiency for a given cycle. In addition, the use of a pressurized SOFC will also allow integration with a combustion turbine. The combustion turbine selected for integration by Siemens Westinghouse is the unique 1.4 MW Heron reheat combustion turbine, a proposed product of Heron (53). 

Does the cell voltage increase, decrease, or remain the same when each of the following changes is made Explain. 

The current efficiency increases with increasing anode-cathode distance, because for a longer anode-cathode distance there is less convection, less interaction between gas bubbles and the metal, and more stable conditions. It was found that the current efficiency is independent of the anode-cathode distance above a certain distance. However, the ohmic drop in the electrolyte increases with the interpolar distance, so the cell voltage increases. These two factors influence the energy efficiency in an opposite manner. Furthermore, the heat balance of the cell sets limits to the variation of the anode-cathode distance. 

Electrolyte Loss due to volatilization Loss due to filling inside the electrodes Loss due to reaction with the separator plate Decrease in the conductivity Increase in the resistivity of the layer Decrease in the cell voltage Increase in the polarization of electrodes... 

C and caustic products of 20-40 weight percent. The cell voltage increases dramatically with caustic strength. The ohmic drop of the membrane or its electrical resistance increases with increasing caustic concentration and also with brine concentration but to a lesser extent with brine than caustic strength. 

Concentration of Sodium Sulfate Solutions. A concentration unit is always necessary for both two- and three-compartment cells when the feed consists of dilute sodium sulfate solutions, because the cell voltage increases rapidly when the sodium sulfate concentration is <10%. The methods available are reverse osmosis, electrodialysis, and evaporation. With the present average European prices of steam and electric energy, evaporation seems to be the best method for concentrating up to 20% diluted feed solutions having a salt content around 3-5%. 

Cell voltage increase should be limited to a definite upper limit so as to avoid excessive gassing in the battery. 

During the electrolysis, the cell voltage increases gradually in time, thus indicating the accumulation of sparingly soluble intermediates on the electrode (Fig. 6.15). 

Current density As current density increases, the cell voltage increases linearly, and the current efficiency and the water transport coefficient remain essentially constant. 

Figure 23.6 shows the dependence of the half-cell voltage [t] in our notation) on time in the poisoning experiments of Konysheva et al. [17]. Comparison of Figures 23.5 and 23.6 shows that the model qualitatively well reproduces the experimental data. At low cell currents, the experimental cell voltage increases hnearly with time cf the curves FL13Cr-0.07, FL13Cr-0.18, and the lower curve... 

The cell voltage increases sharply with current density, predominantly because of (i). It is therefore important to choose an electrolyte of maximum conductivity and for this reason aqueous KOH is usually employed. Increasing the concentration of the KOH solution (e.g. from 30-40 wt%) increases its conductivity. There is also a second effect which becomes increasingly significant at higher temperatures the reduced vapor pressure associated with higher concentration results in a lower water vapor tension in the product gases and so a reduction in the enthalpic effect. 

Migration of lithium ions between electrodes continues as the cell voltage increases. Gas evolution and temperature rise in the outer casing are low. 

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