Thermo Flashcards

1
Q

A steam-water mixture is initially saturated with a quality of 50 percent when a small amount of heat is added. Assuming the pressure remains constant and the mixture remains saturated, the quality of the mixture will __________; and the temperature of the mixture will __________.

A. increase; increase

B. increase; remain the same

C. remain the same; increase

D. remain the same; remain the same

A

ANSWER: B.

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2
Q

A liquid is saturated with 0 percent quality. Assuming pressure remains constant, the addition of a small amount of heat will… A. raise the steady-state liquid temperature above the boiling point. B. result in a subcooled liquid. C. result in some of the liquid vaporizing. D. result in a superheated liquid.

A

ANSWER: C.

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3
Q

A steam-water mixture is initially saturated with a quality of 95 percent when a small amount of heat is added to the mixture. If the mixture remains saturated and pressure remains constant, the temperature of the mixture will __________; and the quality of the mixture will __________. A. increase; remain the same B. increase; increase C. remain the same; remain the same D. remain the same; increase

A

ANSWER: D.

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4
Q

An open container holds 1.0 lbm of saturated water at standard atmospheric pressure. The addition of 1.0 Btu will… A. raise the temperature of the water by 1°F. B. vaporize a portion of the water. C. increase the density of the water. D. result in 1°F of superheat.

A

ANSWER: B.

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5
Q

An open container holds 1.0 lbm of saturated water at standard atmospheric pressure. The addition of 4.0 Btu will… A. result in 4°F of superheat. B. vaporize a portion of the water. C. increase the density of the water. D. raise the temperature of the water by 4°F

A

ANSWER: B.

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6
Q

The temperature of a quantity of water is 212°F. Which one of the following parameters, when paired with the temperature, provides insufficient information to determine whether the water is a saturated liquid rather than a saturated liquid-vapor mixture? A. Enthalpy B. Entropy C. Pressure D. Specific volume

A

ANSWER: C.

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7
Q

A steam-water mixture is initially saturated with a quality of 50 percent when a small amount of heat is added. If pressure remains constant and the mixture remains saturated, mixture steam quality will __________; and mixture temperature will __________. A. increase; increase B. increase; remain the same C. remain the same; increase D. remain the same; remain the same

A

ANSWER: A.

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8
Q

Consider a saturated steam-water mixture with a quality of 99 percent. If pressure remains constant and heat is removed from the mixture, the temperature of the mixture will __________; and the quality of the mixture will __________. (Assume the mixture remains saturated.) A. decrease; increase B. decrease; decrease C. remain the same; increase D. remain the same; decrease

A

ANSWER: D.

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9
Q

Which one of the following will occur if 500 Btu is removed from 1.0 lbm of dry saturated steam at 800 psia? (Assume that pressure does not change.) A. Temperature will decrease. B. Density will decrease. C. Specific volume will decrease. D. Enthalpy will increase.

A

ANSWER: C.

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10
Q

Which one of the following will decrease if heat is added to a saturated vapor at a constant pressure? A. Density B. Temperature C. Entropy D. Enthalpy

A

ANSWER: A.

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11
Q

Consider a saturated steam-water mixture with a quality of 79 percent. If pressure remains constant and heat is added to the mixture, the temperature of the mixture will __________; and the quality of the mixture will __________. (Assume the mixture remains saturated.) A. increase; increase B. increase; remain the same C. remain the same; increase D. remain the same; remain the same

A

C. remain the same; increase

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12
Q

Consider a saturated steam-water mixture at 500°F with a quality of 90 percent. If the pressure of the mixture is decreased with no heat gain or loss, the temperature of the mixture will __________; and the quality of the mixture will __________. (Assume the mixture remains saturated.) A. decrease; decrease B. decrease; increase C. remain the same; decrease D. remain the same; increase

A

B. decrease; increase

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13
Q

Consider dry saturated steam at 470°F. If the pressure of the steam remains constant while heat is added, steam temperature will __________; and steam quality will __________. A. remain the same; remain the same B. remain the same; increase C. increase; remain the same D. increase; increase

A

C. increase; remain the same

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14
Q

Consider a sealed vessel containing 1,000 lbm of a saturated steam-water mixture at 500°F. The vessel is perfectly insulated with no heat gain or loss occurring. If a leak near the bottom of the vessel results in a loss of 10 percent of the liquid volume from the vessel, the temperature of the mixture will __________; and the overall quality of the mixture will __________. (Assume the mixture remains saturated.) A. decrease; increase B. decrease; decrease C. remain the same; increase D. remain the same; decrease

A

A. decrease; increase

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15
Q

Consider 1.0 lbm of dry saturated steam at 200 psia. If pressure does not change, which one of the following will be caused by the addition of 6.0 Btu to the steam? A. The steam will remain saturated at the same temperature. B. The steam will become superheated at the same temperature. C. The steam will remain saturated at a higher temperature. D. The steam will become superheated at a higher temperature.

A

D. The steam will become superheated at a higher temperature

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16
Q

What is the approximate quality of wet steam leaving a reactor at 530 psig with an enthalpy of 928.9 Btu/lbm? A. 25 percent B. 37 percent C. 63 percent D. 75 percent

A

C. 63 percent

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17
Q

Which one of the following describes the effect of removing heat from a saturated steam-water mixture that remains in a saturated condition? A. Temperature will increase. B. Temperature will decrease. C. Quality will increase. D. Quality will decrease.

A

D. Quality will decrease

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18
Q

Which one of the following is the approximate quality of a saturated steam-water mixture at 467°F with an enthalpy of 1,000 Btu/lbm? A. 24 percent B. 27 percent C. 73 percent D. 76 percent

A

C. 73 percent

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19
Q

The temperature of a saturated steam-water mixture is 467°F. Which one of the following parameter values, when paired with the temperature, provides insufficient information to determine the quality of the mixture? A. Pressure is 499.96 psia. B. Enthalpy is 977.33 Btu/lbm. C. Entropy is 1.17 Btu/lbm -°R. D. Specific volume is 0.817 ft3/lbm.

A

A. Pressure is 499.96 psia.

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20
Q

Given a reactor operating at 985 psig with a feedwater inlet temperature of 400°F, what is the amount of feedwater subcooling? A. 136.6°F B. 140.6°F C. 144.6°F D. 148.6°F

A

C. 144.6°F

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21
Q

What effect will occur if heat is removed from water that is in a subcooled condition? A. Temperature of the water will increase. B. Enthalpy of the water will decrease. C. Quality of the water will increase. D. Density of the water will decrease.

A

B. Enthalpy of the water will decrease.

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22
Q

An open vessel contains 1.0 lbm of water at 206°F and standard atmospheric pressure. Which one of the following will be caused by the addition of 3.0 Btu to the water? A. The water temperature will rise by approximately 3°F. B. Approximately 3 percent of the water mass will vaporize. C. The water density will decrease by approximately 3 percent. D. The water will become superheated by approximately 3°F.

A

A. The water temperature will rise by approximately 3°F.

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23
Q

Which one of the following is the approximate temperature of a saturated steam-water mixture that has an enthalpy of 1,150 Btu/lbm and a quality of 95 percent? A. 220°F B. 270°F C. 360°F D. 440°F

A

C. 360°F

24
Q

Dry saturated steam undergoes an ideal expansion process in an ideal turbine from 1,000 psia to 28 inches Hg vacuum. Approximately how much specific work is being performed by the turbine? A. 1,193 Btu/lbm B. 775 Btu/lbm C. 418 Btu/lbm D. 357 Btu/lbm

A

C. 418 Btu/lbm

25
Q

Dry saturated steam undergoes an ideal expansion process in an ideal turbine from 294 psig to 27 inches Hg vacuum. Approximately how much specific work is being performed by the turbine? A. 1,203 Btu/lbm B. 418 Btu/lbm C. 343 Btu/lbm D. 308 Btu/lbm

A

C. 343 Btu/lbm

26
Q

Which one of the following is the approximate reactor coolant heatup rate if reactor vessel pressure increases from 470 psig to 980 psig over a two-hour period? A. 40°F/hr B. 60°F/hr C. 80°F/hr D. 120°F/hr

A

A. 40°F/hr

27
Q

Given a set of steam tables that lists the following parameters for saturated steam and water:  Pressure  Enthalpy  Specific volume  Entropy  Temperature One can determine the __________ of a saturated steam-water mixture given only the __________. A. temperature; enthalpy B. temperature; pressure C. pressure; entropy D. pressure; specific volume

A

B. temperature; pressure

28
Q

The saturation pressure corresponding to 400°F is approximately… A. 232 psia. B. 247 psia. C. 262 psia. D. 444 psia.

A

B. 247 psia.

29
Q

An operator suspects that a steam line temperature instrument reading is not correct. A recently calibrated pressure gauge sensing steam pressure for the same steam line indicates 351 psig. Assuming the system is operating at saturation pressure, what approximate temperature should the temperature instrument indicate? A. 424°F B. 428°F C. 432°F D. 436°F

A

D. 436°F

30
Q

The saturation temperature for steam at a pressure of 785 psig is approximately… A. 510°F. B. 513°F. C. 515°F. D. 518°F.

A

D. 518°F.

31
Q

Which one of the following is the approximate quality of steam leaving a cyclone separator at 985 psig and 1,186 Btu/lbm? A. 95 percent B. 96 percent C. 97 percent D. 99 percent

A

D. 99 percent

32
Q

The saturation pressure for water at 328°F is approximately… A. 85 psig. B. 100 psig. C. 115 psig. D. 130 psig.

A

A. 85 psig.

33
Q

Dry saturated steam at 250 psia enters turbine X. Superheated steam at 250 psia and 500°F enters turbine Y. Both turbines are 100 percent efficient and exhaust to a condenser at 1 psia. Which one of the following lists the approximate percentages of moisture at the exhausts of turbines X and Y? A. Turbine X = 24.5%; turbine Y = 20.8% B. Turbine X = 26.3%; turbine Y = 13.0% C. Turbine X = 24.5%; turbine Y = 13.0% D. Turbine X = 26.3%; turbine Y = 20.8%

A

A. Turbine X = 24.5%; turbine Y = 20.8%

34
Q

Cooling water exits a fuel channel with an enthalpy of 1,195 Btu/lbm at a reactor pressure of 1,050 psig. What is the state of the fluid at the exit of the fuel channel? A. Saturated B. Superheated C. Compressed D. Subcooled

A

B. Superheated

35
Q

Which one of the following sets of parameters for a saturated steam-water mixture will result in the highest quality? A. 500°F; 1,100 Btu/lbm B. 320°F; 1,070 Btu/lbm C. 200°F; 1,040 Btu/lbm D. 160°F; 960 Btu/lbm

A

C. 200°F; 1,040 Btu/lbm

36
Q

Which one of the following is the enthalpy of steam at 235.3 psig and 500°F? A. 1,201.1 Btu/lbm B. 1,202.2 Btu/lbm C. 1,263.5 Btu/lbm D. 1,286.6 Btu/lbm

A

C. 1,263.5 Btu/lbm

37
Q

A saturated steam-water mixture leaving a reactor core has the following parameter values: Temperature = 550.5°F Pressure = 1,035 psig Quality = 14.5 percent Which one of the following is the approximate enthalpy of the steam-water mixture? A. 610 Btu/lbm B. 643 Btu/lbm C. 720 Btu/lbm D. 860 Btu/lbm

A

B. 643 Btu/lbm

38
Q

A saturated steam-water mixture leaving a reactor core has the following parameter values: Temperature = 550.5°F Pressure = 1,035 psig Quality = 20 percent Which one of the following is the approximate enthalpy of the steam-water mixture? A. 641 Btu/lbm B. 678 Btu/lbm C. 751 Btu/lbm D. 1,063 Btu/lbm

A

B. 678 Btu/lbm

39
Q

What is the approximate amount of heat required to convert 3.0 lbm of water at 100°F and 100 psia to dry saturated steam at 100 psia? A. 889 Btu B. 1,119 Btu C. 2,666 Btu D. 3,358 Btu

A

D. 3,358 Btu

40
Q

A nuclear power plant is operating with the following main steam parameters at the main turbine steam inlet valves: Pressure = 900 psia Quality = 98 percent The main turbine steam chest pressure is 400 psia. Assuming an ideal throttling process, what is the quality of the steam in the steam chest? A. 97 percent B. 98 percent C. 99 percent D. 100 percent

A

A. 97 percent

41
Q

A saturated steam-water mixture with a quality of 30 percent leaves a main turbine at 1.0 x 106 lbm/hr and enters a steam condenser at 2.0 psia. Condensate enters the hotwell at 118°F. Which one of the following is the approximate condenser heat transfer rate? A. 3.1 x 108 Btu/hr B. 5.8 x 108 Btu/hr C. 7.2 x 108 Btu/hr D. 9.9 x 108 Btu/hr

A

A. 3.1 x 108 Btu/hr

42
Q

Which one of the following is the approximate amount of heat required to convert 2.0 lbm of water at 100°F and 100 psia to dry saturated steam at 100 psia? A. 1,119 Btu B. 1,187 Btu C. 2,238 Btu D. 2,374 Btu

A

C. 2,238 Btu

43
Q

Turbine X is an ideal steam turbine that exhausts to a condenser at 1.0 psia. Turbine X is driven by dry saturated steam at 500 psia. Which one of the following lists the approximate specific work output of turbine X and the moisture content of the steam exiting turbine X? Specific Work Moisture Content A. 388 Btu/lbm 72% B. 388 Btu/lbm 28% C. 817 Btu/lbm 72% D. 817 Btu/lbm 28%

A

B. 388 Btu/lbm 28%

44
Q

A steam line is carrying steam at 500 psia and 507°F. Approximately how much specific ambient heat loss is required before moisture formation can occur in the steam line? A. 31 Btu/lbm B. 45 Btu/lbm C. 58 Btu/lbm D. 71 Btu/lbm

A

A. 31 Btu/lbm

45
Q

Which one of the following is the approximate amount of heat required to convert 2.0 lbm of water at 100°F and 100 psia to superheated steam at 400°F and 100 psia? A. 1,119 Btu B. 1,159 Btu C. 2,239 Btu D. 2,319 Btu

A

D. 2,319 Btu

46
Q

What is the approximate specific heat (Btu/lbm-°F) of water at 300°F and 100 psia? A. 1.03 Btu/lbm-°F B. 1.11 Btu/lbm-°F C. 1.17 Btu/lbm-°F D. 1.25 Btu/lbm-°F

A

A. 1.03 Btu/lbm-°F

47
Q

The theoretical maximum efficiency of a steam cycle is given by the equation: Effmax = (1 - Tout/Tin) x 100% where Tout is the absolute temperature for heat rejection and Tin is the absolute temperature for heat addition. (Fahrenheit temperature is converted to absolute temperature by adding 460°F.) A nuclear power plant is operating with a stable reactor vessel pressure of 900 psia. What is the approximate theoretical maximum steam cycle efficiency this plant can achieve by establishing its main condenser vacuum at 1.0 psia? A. 35 percent B. 43 percent C. 65 percent D. 81 percent

A

B. 43 percent

48
Q

With a nuclear power plant operating near rated power, air inleakage into the main condenser causes main condenser pressure to increase from 1.0 psia to 2.0 psia. Given the following:  Initial main condenser condensate depression was 4°F.  After the plant stabilizes, main condenser condensate depression is 2°F with main condenser pressure at 2.0 psia. Which one of the following is the approximate increase in main condenser specific heat rejection needed to restore condensate depression to 4°F? A. 2 Btu/lbm B. 4 Btu/lbm C. 8 Btu/lbm D. 16 Btu/lbm

A

A. 2 Btu/lbm

49
Q

A nuclear power plant is operating at a low power level. Main steam at the main turbine steam inlet valves has the following properties: Pressure = 900 psia Quality = 99 percent The main turbine steam chest pressure is 300 psia. Which one of the following is the approximate temperature of the steam in the steam chest? A. 417°F B. 439°F C. 496°F D. 532°F

A

A. 417°F

50
Q

A nuclear power plant is operating at 100 percent power. Steam is escaping to atmosphere through a flange leak in a steam supply line to the low pressure section of the main turbine. Given:  Steam line pressure is 300 psia.  Steam line steam temperature is 440°F. What is the approximate temperature of the steam as it reaches standard atmospheric pressure? A. 212°F B. 268°F C. 322°F D. 358°F

A

D. 358°F

51
Q

A steam line is carrying dry saturated steam at 500 psia. Approximately how much heat addition to the steam is necessary to achieve 60°F of superheat? A. 31 Btu/lbm B. 45 Btu/lbm C. 58 Btu/lbm D. 71 Btu/lbm

A

B. 45 Btu/lbm

52
Q

Refer to the drawing of a water-filled manometer (see figure below).

The manometer is installed across an orifice in a ventilation duct to determine the direction of airflow. With the manometer conditions as shown, the pressure at P1 is __________ than P2; and the direction of airflow is __________.

A. greater; left to right

B. greater; right to left

C. less; left to right

D. less; right to left

A

ANSWER: A.

53
Q

Refer to the drawing of two water storage tanks with four differential pressure (D/P) level detectors (see figure below).

The tanks are identical and are being maintained at the same constant water level with 17 psia gas pressure above the water. The tanks are surrounded by standard atmospheric pressure. The temperature of the water in the tanks and reference legs is 70°F.

Which one of the level detectors is sensing the greatest D/P?

A. No. 1

B. No. 2

C. No. 3

D. No. 4

A

ANSWER: B.

54
Q

Refer to the drawing of a water-filled manometer (see figure below).

The manometer is installed across an orifice in a ventilation duct to determine the direction of airflow. With the manometer conditions as shown, the pressure at P1 is __________ than P2; and the direction of airflow is __________.

A. less; right to left

B. less; left to right

C. greater; right to left

D. greater; left to right

A

ANSWER: A.

55
Q

Refer to the drawing of two water storage tanks with four differential pressure (D/P) level detectors (see figure below).

The tanks are identical with equal water levels and 20 psia gas pressure above the water. The tanks are surrounded by standard atmospheric pressure. The temperature of the water in the tanks and reference legs is 70°F.

If each detector experiences a ruptured diaphragm, which detector(s) will produce a lower level indication? (Assume that actual tank and reference leg water levels do not change.)

A. No. 1 only

B. No. 2 only

C. No. 1, 2, and 3

D. No. 2, 3, and 4

A

ANSWER: D.

56
Q
A