Question

please Answer 100% if you have any doubt please tell me

1. About the effect of the operating pressure on the hydrogen fuel cell performance

a. The net voltage will increase in the optimistic model if the pressure increases. b. There is a maximum voltage increase in the realistic model. c. The difference between the two models is related to the different parameter values. d. In a real application, voltage from a fuel cell system will increase if the inlet gas pressure increases.

2. About alkaline electrolyte fuel cells, a. The electrolyte can be mobile or static. b. The mobile electrolyte AFCs have a problem in short circuit. c. Pure oxygen should be used in the mobile electrolyte AFCs. d. Each cell in a mobile electrolyte AFC system has its own electrolyte.

3. About direct methanol fuel cells a. Methanol is a good energy carrier with higher energy density than hydrogen. b. Methanol is easy to be stored. c. The net energy density in methanol is higher than that in hydrogen. d. The cost of methanol is low.

4. About the direct methanol fuel cells a. The reaction rate on the anode of a DMFC is lower than that on the anode of a H2 FC. b. The open-circuit voltage of a DMFC is higher than that of a H2 FC. c. Water is needed in the cathode reaction. d. Carbon dioxide will be generated on the anode.

5. In power electronics,
a. Thyristor, MOSFET, and IGBT are usually used as switches. b. Buck and booster are used to change the DC voltage. c. There is always an energy loss in switches, converters, and inverters. d. The ripples can always be found in the outputs from converter and inverter.

6. About inverters, a. Pure sine wave is good to the grid and electric motors. b. Pulse-width modulation is usually used to get a sine wave. c. Fourier analysis is used to determine the quality of the output from an inverter. d. A H-bridge circuit is used in a single-phase pulse-width modulation.

7. About electric motors, a. Brushed DC motors are not used when the power is supplied by hydrogen fuel cell system. b. The rotor is a permanent magnet in an induction motor. c. The rotor is a permanent magnet in a switched reluctance motor. d. The rotor is a permanent magnet in a brushless DC motor.

8. In a steam reforming process, a. The reforming reaction is endothermic. b. The reforming reaction is exothermic. c. The hydrogen concentration increases when the operating temperature increases. d. The heat generated from a fuel cell stack can be supplied to a internal reformer

only question 1 needed More information do others

Answer 1

1)option D because as the pressure increases , the mole fraction of oxygen in fuel cell increases causing voltage generated to increase

2)option A , electrolyte can be mobile or static. Static electrolyte was used in Apollo spacecraft and mobile or flowing is used in Elo flux fuel cell .

3)Option A because key advantage of methanol based fuel cell is that due to high energy density of methanol they are best suited to transfer energy .

4)Option D , carbon dioxide is generated at anode as waste or byproduct in the DMFC .

5)Option B is true because buck boost type chopper can either increase or decrease the DC input voltage levels .

6)option A correct because more the sine wave shape , more better the form factor , lesser are harmonics in pure sine best case of no harmonics , so best power quality available to consumer.

7)Option D , rotor is made of permanent magnet in BLDC motor so that no need of brush required.

8)option A is true , because reforming reaction needs large amount of heat so it becomes endothermic process.