A solid oxide full cell (SOFC) is an electrochemical energy conversion device wi
ID: 848679 • Letter: A
Question
A solid oxide full cell (SOFC) is an electrochemical energy conversion device with anode and cathode sides of a thin solid ceramic membrane. A fuel such as hydrogen reacts at the anode side, while oxyen (from air) reacts at the cathode. The fuel does not cross the ceramic membrane.
Hydrogen is used as the fuel in the SOFC to power a load according to the following chemical reactions
Anode: H2 + O^2- -> H2O + 2e-
Cathode: .5 O2 + 2e- -> O^2-
Overall H2 + .5 O2 -> H2O
One of the fuel cells on Depot campus is operated at a voltage of .8V with the mass inputs as specified below. The H2O product is collected via condensation and measured as a volume of liquid vs. time. A diagram of this process is given below.
20g /s H2 ----> ( Anode Chamber) ----> (Water chamber) ----> H2
1450 g/s air ----> (Cathode chamber) -----> cathode exhaust
What is the conversion of H2 and O2 if the condensation rate is 5.4 L/min liquid H2O? Assume that all of the water is condensed and the T =25 C. How much power is generated from the fuel cell?
Notes:
a. Power = current * voltage (watts)
b. 1 mole e- = 96485 coulombs and 1 amp = 1 coulomb /sec
Explanation / Answer
Volume of water condensing=5.4 L/min
Mass of water condensing=Volume*density
=5.4*1000 [Density of water at 25? is 1000g/ltr]
=5400g
Moles of water precipitated=Mass/mol wt
=5400/18=300 mol
Water precipitated per seconde=300/60=5 mol/sec
1mol water gives 2mol of electron.
Thus current produced/sec=5*2=10 mol electron/sec
=10*96485=964850 A
Power produced=Current*voltage=964850*0.8=771880 W
=771.880 kW
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