Wednesday, December 30, 2009

ANSWERS TO BOARD EXAM REVIEWER: POWER ELEMENTS








Here's the answers to the questions posted on the last article.
1. The measure of how effective a boiler is in transferring heat from furnace to the water and steam.
Answer: C. Boiler efficiency

2. A heat exchanger used to remove dissolved air in water?
Answer:b. Deaerator

3. A state of water where the quantity of steam and liquid water is indistinguishable.
Answer: a. Critical point
Reference: p.62, Thermodynamics 6th.Ed., Faires and Simmang



4. A power plant that harness energy from the difference in temperature between the depths of the ocean.
Answer: a. OTEC
OTEC stands for Ocean Thermal Energy Conversion

5. The most efficient thermal cycle.
Aswer: d. Carnot Cycle
Making a square shape when plotted to the T-s diagram, Carnot Cycle is by far the most efficient thermal cycle.



6. A steam power plant that take a portion steam from turbine stages and use them to heat the water prior to its entry to the boiler.
Answer: b. Regenerative power plant
reference: p.238, Thermodynamics 6th.Ed., Faires and Simmang

7. The amount of heat needed to raise one gram of water by 1 degree Celcius.
Answer: c. Calorie

8. What isotope of Uranium is capable of atomic fission and therefore can be used as a fuel in nuclear power plants.
Answer: c. U-235

9. A hypothetical body capable emitting all its energy by radiation.

Answer: d. Black body
Reference: p.62, Thermodynamics 6th.Ed., Faires and Simmang

10. When the stack of the furnace emits a black smoke, it indicates that...
Answer: b. The amount of air used in burning the fuel is not enough

11. The difference between the steam temperature and its boiling temperature at a given pressure.
Answer: a. Degree superheat
Reference: p.61, Thermodynamics 6th.Ed., Faires and Simmang

12. The percentage of steam in a liquid water-steam mixture system is often referred to as
Answer: b. Quality
Reference: p.61, Thermodynamics 6th.Ed., Faires and Simmang

13. What do you call a water on its liquid form when it’s temperature is below its saturation temperature at given pressure.
Answer: c. Subcooled liquid
This can be a little tricky since "subcooled liquid" and "compressed liquid" states are identical. The BEST answer though is "subcooled liquid" because the question is referring to the temperature. On the other hand, if the question refrences the pressure, the answer

14. In a PV chart, what is the area below the process curve?
Answer: b. Work non-flow
Integral of pdV is work non-flow.

15. It is measure of the amount of matter present in a body and contains the Avogadro’s number of particles.
Answer: d. Mole
Mole is the amount of substance that contains the Avogadro's number (6.022E23) particles.
Reference: p.17, Thermodynamics 6th.Ed., Faires and Simmang

16. The amount of energy used to change the temperature of a body.
Answer: a. Sensible heat
When there is no change in temperature (during changes in phase) the heat used is called Latent Heat.

17. An instrument used to determine the heating value of a fuels.
Answers: a. Calorimeter or d. Bomb calorimeter
Both a and d can be the correct answer, but d is more specific.

18. The work produced by the turbine is a…
Answer: d. Work steady flow
Turbine is an open system so the work produced is work steady flow.

19. The process occurring in heat exchangers are ideally…
Answer: c. Isobaric
All heat exchagers operates at contant pressure (ideally).

20. The entropy- enthalpy diagram of water is also known as…
Answer: a. Mollier chart
Reference: p.72, Thermodynamics 6th.Ed., Faires and Simmang

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