3. Define/describe the following terms or acronyms: (a) PTFE, (b) GDL, (c) MEA, (d) Ni- YSZ. What is a cermet material? (3x5-15) Technology, ME 482 1. An experimental PEM fuel cell operates at a temperature of 80°C and a pressure of 1 atm. Consider a single cathode channel of this fuel cell as shown: 1 mm Airflow passage to cathode 4-5 mm depth in paper Imm cathode 2 mm The dimensions of the channel are: area: length: 1 mm 5 mm The width of the MEA that corresponds to a single channel is 2 mm. For a stoichiometric flow ratio of 2-2 calculate: (a) The amount of oxygen entering the channel for a current density of 1.0 A/cm² in moles/sec and kg/sec, (b) The amount of dry air entering in moles/sec and kg/see assuming molar nitrogen to oxygen ratio of 79/21. (c) The volumetric flow rate of air in m'is and the inlet bulk velocity of the air in m/s assuming ideal gas behavior. (30) 4. A new large capacity water heating system is expected to save $4000 each year on fuel cost. If any increase in fuel price is neglected, what is the present worth of fuel savings in the 10th year for an interest rate of 12 %? (10) 2. A gas cylinder is full of hydrogen gas at room temperature and 2000 psig pressure. This cylinder has been proposed as a fuel tank for a fuel cell powered laptop computer. Note that the volume of the cylinder is 49.9 L. a. Determine the energy content in kJ within the cylinder when the hydrogen is combusted to make liquid water. Use the ideal gas law, PV = nRT. (1 atm 14.7 psig; R 0.08206 L.atm/mol.K) b. The efficiency of a fuel cell is defined according to the equation, n electrical energy output fuel thermal energy input (Eelectrical/Eotal), with the remaining thermal energy being converted into heat. If -0.6, how much of the combustion energy is converted into electricity? How much is converted into heat? c. The energy consumption Electrical of an electronic device is equal to the power consumption rate P multiplied by the operating time 1. Suppose you have a 100 W fuel cell (which can power a laptop computer). How long can you operate the fuel cell with this gas cylinder? Additional information: (AH)20-285.84 kJ/mol (liquid water) (AH)20-241.83 kJ/mol (vapor water) (30) 5. Match the following five scenarios to the five corresponding hypothetical j-v curves in the following figure: 1. A SOFC limited by an extremely high electrolyte resistance. 2. A PEMFC suffering from a large leakage current loss. 3. A PEMFC severely limited by poor reaction kinetics 4. A PEMFC with an extremely low ohmic resistance 5. A SOFC suffering from reactant starvation Cuner denty (Aom (4) Current density (Alom (b) Curent density (Albe (d) Current density (A (el Cell voltage (V Qument deity (c) (15)