MS-EST143_HW8_2011 - MS/EST 143, Problem Set #8 assigned...

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1 MS/EST 143, Problem Set #8 assigned 05/22/11 due 05/27/11 1. The power generation characteristics of a fuel cell are described by the polarization curve (cell voltage as a function of current density). In a certain solid oxide fuel cell (with an oxygen ion conducting electrolyte), it is observed that, as current is drawn, the voltage decreases almost linearly from the Nernst value, suggesting that the voltage losses are primarily ohmic in nature. The cell is operated at 700 °C by supplying air to the cathode and H 2 saturated with 3% water vapor to the anode. It is also observed that the limiting current density (current at zero voltage) is 4.2 A/cm 2 . (i) Plot the polarization curve. Calculate the total area specific resistance of the cell from the slope of the polarization curve. (ii) Plot the power density of the fuel cell. What is the peak (or maximum) power density? At what values of voltage and current density does this peak occur? (iii)
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This note was uploaded on 01/03/2012 for the course MS 143 taught by Professor List during the Fall '10 term at Caltech.

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