Answer Happy

3. Use MATLAB or a similar mathematical program, based on the data of Table 3.3, to plot the graphs like those of Figures 3.1 and 3.2. The simple script file below could be your starting point. Eoc=1.031, A=0.03, r=0.000245, m=2.11E-5, n=0.008 i=linspace (1,1000,200) v= Eoc - r*i - A* log(i) - m*exp(n*i) plot (i, v)
Table 3.3 Example values of parameters for equation (3.22). Parameter Low temperature (e.g., PEMFC) High temperature (e.g., SOFC) 1.2 1.0 2 V. (V) in (mA cm2 r (k2 cm) i, (mA cm2) A (V) B (V) i (mAcm 2 2 30 x 10-6 0.067 300 x 10-6 300 0.03 0.06 0.05 0.08 900 900
1.2 1.0 "No loss' voltage of 1.2 V Even the open circuit voltage is less than the theoretcial no loss value Rapid initial fall in voltage Voltage falls more slowly and graph is fairly linear 0.8 - Cell voltage (V) 0.6 - 0.4 T L Voltage begins to fall faster at higher currents 0.2 T 0 800 200 400 600 1000 Current density (mA cm) Figure 3.1 Graph showing the voltage for a typical low temperature, air pressure, fuel cell.
1.2 1.0 "No loss' voltage of 1.0 V Graph is fairly linear 0.8 Cell voltage (V) 0.6 Very small initial fall in voltage, and open circuit voltage is very close to theoretical value 0.4 - Voltage begins to fall faster at higher currents 0.2 200 400 600 800 1000 Current density (mA cm2 Figure 3.2 Graph showing the voltage of a typical air pressure fuel cell operating at about 800°C.