Cell voltage change

But [Cl ] in the left half-cell is constant, fixed by the solubility of KC1, with which the solution is saturated. Therefore, the cell voltage changes only when the quotient [Fe2+]/[Fe3+] changes. 

We now set out to calculate how the cell voltage changes as Fe2+ is titrated with Ce4+. The titration curve has three regions. 

The cell voltage changed between 2.7 and 2.9 V. After an operation, the same reactor treated other waste systems successfully, also on a long-term basis. The data demonstrated that the Pd cathodes can be subjected for a relatively long HDH operation. 

The OCV seems to be of less practical use. It is much more useful for a fuel cell to work under a load, with power being delivered to the users. With the electric energy output, the fuel cell voltage will decrease as the electric current load increases. A popular way to evaluate a fuel cell is to measure its polarization curve (abbreviated as I-V curve ), which is a plot showing the cell voltage change with current or current density. Figure 1.20 shows a typical polarization curve obtained with a PEMFC. 

Similarly if the cell voltage changes from V] to Va and the ohmic drop is negligible and E(anode) (SE) is constant then ... 

Cell voltage change with time after 10 ppm CO/70% H2/30% CO2 was switched to 50 ppm CO/70% H2/30% CO2 for MEAs with different anode Pt-Ru loadings. Current density = 200 mA/cm Nation 1135 membrane. (From Qi, Z. et al. 2002. /. Power Sources 111 239-247. With permission.)... 

Pathapati has conducted research in this area. Figure 10.45 describes the current density from 50 to 500 mA cm 2 and the fuel cell voltage changes with the excess air coefficients of 1.1,1.3, and 1.5 respectively. With the presupply excess air coefficient increasing, the dynamic response of the fuel cell performance improves, becoming more stable and faster. When the excess air coefficient is 1.5, starvation does not occur. 

Because the reduction reaction of Mn02 is not a well-defined reaction, the Nemst equation cannot be applied successfully, and the cell voltage changes unpredictably with time and discharge condition. 

Fuel cell testing is the most rehable and commonly used method to evaluate a PEM fuel cell. Its purpose is to assess the aspects of fuel cell performance, such as how the cell voltage changes when the fuel cell load (current or current density) is altered, or how the load changes when the cell voltage is altered, or... 

FIGURE 9.4 Calculated anode, cathode, and total cell voltage changes with backpressure as a function of current density. In the calculation, —... 

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