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Heat Exchangers and Condensers Flashcards

1
Q

The rate of heat transfer between two liquids in a heat exchanger will increase if the… (Assume
single-phase conditions and a constant specific heat for both liquids.)

A

flow rates of both liquids increase by 10 percent.

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2
Q 
Refer to the drawing of an operating lube oil heat exchanger (see figure below).
Given the following information:
cp-oil = 1.1 Btu/lbm-°F
cp-water = 1.0 Btu/lbm-°F
Toil in = 174°F
Toil-out = 114°F
Twater-in = 85°F
Twater-out = 115°F
ṁ oil = 4.0 x 104 lbm/hr
ṁ water = ?
What is the approximate mass flow rate of the cooling water?
A

8.8 x 104 lbm/hr

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3
Q

The rate of heat transfer between two liquids in a single-phase heat exchanger will decrease if the…
(Assume constant specific heat capacities.)

A

flow rate of the colder liquid decreases by 10 percent.

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4
Q 
Refer to the drawing of an operating lube oil heat exchanger (see figure below).
Given the following information:
ṁ oil = 2.0 x 104 lbm/hr
ṁ water = 3.0 x 104 lbm/hr
cp-oil = 1.1 Btu/lbm-°F
cp-water = 1.0 Btu/lbm-°F
Tcw-in = 92°F
Tcw-out = 125°F
Toil-in = 180°F
Toil-out = ?
Which one of the following is the approximate temperature of the lube oil exiting the heat exchanger
(Toil-out)?
A

135°F

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5
Q

Which one of the following will reduce the heat transfer rate between two liquids in a heat exchanger?
(Assume single-phase conditions and a constant specific heat for both liquids.)

A

The inlet temperature of the colder liquid increases by 20°F.

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6
Q

The rate of heat transfer between two liquids in a heat exchanger will increase if the: (Assume
single-phase conditions and a constant specific heat for each liquid.)

A

flow rate of the hotter liquid increases by 10 percent.

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7
Q 
Refer to the drawing of an operating lube oil heat exchanger (see figure below).
Given the following information:
ṁ oil = 1.5 x 104 lbm/hr
ṁ water = 2.5 x 104 lbm/hr
cp-oil = 1.1 Btu/lbm-°F
cp-water = 1.0 Btu/lbm-°F
Tcw-in = 92°F
Tcw-out = 125°F
Toil-in = 160°F
Toil-out = ?
Which one of the following is the approximate temperature of the lube oil exiting the heat exchanger
(Toil-out)?
A

110°F

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8
Q 
Refer to the drawing of an operating lube oil heat exchanger (see figure below).
Given the following information:
cp-oil = 1.1 Btu/lbm-°F
cp-water = 1.0 Btu/lbm-°F
ṁoil = 1.2 x 104 lbm/hr
ṁwater = 1.61 x 104 lbm/hr
Toil in = 170°F
Toil out = 120°F
Twater out = 110°F
Twater in = ?
Which one of the following is the approximate cooling water inlet temperature (Twater in) for the heat
exchanger?
A

69°F

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9
Q 
Refer to the drawing of an operating lube oil heat exchanger (see figure below).
Given the following information:
ṁ oil = 1.8 x 104 lbm/hr
ṁ water = 3.3 x 104 lbm/hr
cp-oil = 1.1 Btu/lbm-°F
cp-water = 1.0 Btu/lbm-°F
Tcw-in = 90°F
Tcw-out = 120°F
Toil-in = 190°F
Toil-out = ?
What is the approximate temperature of the lube oil exiting the heat exchanger (Toil-out)?
A

140°F

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10
Q 
Refer to the drawing of an operating lube oil heat exchanger (see figure below).
Given the following information:
ṁ oil = 1.5 x 104 lbm/hr
ṁ water = 2.5 x 104 lbm/hr
cp-oil = 1.1 Btu/lbm-°F
cp-water = 1.0 Btu/lbm-°F
Toil-in = 160°F
Toil-out = 110°F
Tcw-in = 92°F
Tcw-out = ?
Which one of the following is the approximate temperature of the cooling water exiting the heat
exchanger (Tcw-out)?
A

125°F

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11
Q

The rate of heat transfer between two liquids in a heat exchanger will decrease if the: (Assume
single-phase conditions and a constant specific heat for both liquids.)

A

flow rates of both liquids decrease by 10 percent

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12
Q

Refer to the drawing of a lube oil heat exchanger (see figure below).
Given the following heat exchanger parameters:
• Lube oil flow rate is 200 lbm/min.
• Lube oil enters the heat exchanger at 140°F.
• Lube oil leaves the heat exchanger at 100°F.
• Specific heat of the lube oil is 0.8 Btu/lbm-°F.
• Cooling water flow rate is 400 lbm/min.
• Cooling water enters the lube oil heat exchanger at 60°F.
• Specific heat of the cooling water is 1.0 Btu/lbm-°F.

What is the approximate temperature of the cooling water leaving the lube oil heat exchanger?

A

76°F

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13
Q 
Refer to the drawing of an operating lube oil heat exchanger (see figure below).
Given the following information:
Q̇
oil = 1.0 x 107 Btu/hr
Toil in = 170°F
Toil out = 134°F
Twater in = 85°F
Twater out = 112°F
cp-oil = 1.1 Btu/lbm-°F
cp-water = 1.0 Btu/lbm-°F
ṁwater = ?
Which one of the following is the approximate mass flow rate of the cooling water?
A

3.7 x 105 lbm/hr

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14
Q 
Refer to the drawing of an operating lube oil heat exchanger (see figure below).
Given the following information:
ṁ oil = 1.8 x 104 lbm/hr
ṁ water = 3.3 x 104 lbm/hr
cp-oil = 1.1 Btu/lbm-°F
cp-water = 1.0 Btu/lbm-°F
Tcw-in = 90°F
Tcw-out = 120°F
Toil-in = 170°F
Toil-out = ?
What is the approximate temperature of the lube oil exiting the heat exchanger (Toil-out)?
A

120°F

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15
Q

Refer to the drawing of an operating water cleanup system (see figure below).
If cooling water flow rate is 1.0 x 106 lbm/hr, what is the approximate water flow rate in the cleanup
system?

A

2.2 x 105 lbm/hr

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16
Q

A main turbine-generator was operating at 80 percent load with the following initial steady-state lube
oil and cooling water temperatures for the main turbine lube oil heat exchanger:
Toil in = 174°F
Toil out = 114°F
Twater in = 85°F
Twater out = 115°F
Six months later, the following current steady-state heat exchanger temperatures are observed:
Toil in = 177°F
Toil out = 111°F
Twater in = 85°F
Twater out = 115°F
Assume the lube oil system is a closed system. Also, assume the following did not change:
• Cooling water mass flow rate
• Cooling water and lube oil specific heats
• Heat exchanger heat transfer coefficient
Which one of the following could be responsible for the differences between the initial and current
steady-state heat exchanger temperatures?

A

The current main turbine lube oil mass flow rate is less than the initial flow rate.

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17
Q

A main turbine-generator was operating at 80 percent load with the following initial steady-state lube
oil and cooling water temperatures for the main turbine lube oil heat exchanger:
Toil in = 174°F
Toil out = 114°F
Twater in = 85°F
Twater out = 115°F
Six months later, the current steady-state heat exchanger temperatures are:
Toil in = 174°F
Toil out = 120°F
Twater in = 85°F
Twater out = 120°F
Assume that the lube oil mass flow rate does not change, and that the specific heat values for the
cooling water and lube oil do not change. Also assume that the main turbine lube oil system is a
closed system.
The differences between the initial and current steady-state heat exchanger temperatures could be
caused by the current main turbine-generator load being __________ with the current heat exchanger
cooling water mass flow rate being __________.

A

lower; lower

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18
Q

Refer to the drawing of an operating parallel-flow lube oil heat exchanger (see figure below).
Assume that lube oil (LO) inlet temperature is greater than cooling water (CW) inlet temperature.
Unlike a counter-flow heat exchanger, in a parallel-flow heat exchanger the __________ temperature
can never be greater than the __________ temperature.

A

CW outlet; LO outlet

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19
Q

Refer to the drawing of an operating process water cleanup system (see figure below).
Assume there is no heat loss from the process water cleanup system to the surroundings and the
process water flow rate does not change. If valve D closes fully, what will be the final steady-state
temperature of the process water flowing through the filter?

A

540°F

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20
Q

A counter-flow heat exchanger is being used to cool the lube oil for a main turbine and generator.
The main turbine and generator was initially operating at 100 percent load with the following stable
heat exchanger conditions:
Toil in = 174°F
Toil out = 114°F
Twater in = 85°F
Twater out = 115°F
Main turbine and generator load was reduced, and the heat exchanger cooling water mass flow rate
was decreased to one-half of its initial value, resulting in the following stable current conditions:
Toil in = 178°F
Toil out = 138°F
Twater in = 85°F
Twater out = ?
Assume that the lube oil mass flow rate and the specific heats of both fluids did not change.
Which one of the following is the current cooling water outlet temperature?

A

125°F

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21
Q

Given the following parameter values for a feedwater heater:
Feedwater inlet temperature = 320°F
Feedwater inlet pressure = 1,000 psia
Feedwater mass flow rate = 1.0 x 106 lbm/hr
Extraction steam pressure = 500 psia
Assume that the extraction steam enters the heater as a dry saturated vapor and leaves the heater as a
saturated liquid at 500 psia.
Which one of the following is the approximate mass flow rate of extraction steam required to increase
feedwater temperature to 380°F?

A

8.4 x 104 lbm/hr

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22
Q

Refer to the drawing of an operating parallel-flow lube oil heat exchanger (see figure below).
Unlike a counter-flow heat exchanger, in the parallel-flow heat exchanger the __________
temperature will always be greater than the __________ temperature.

A

LO outlet; CW outlet

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23
Q

Which one of the following will increase the heat transfer rate between two liquids in a heat
exchanger? (Assume single-phase conditions and a constant specific heat for both liquids.)

A

The inlet temperature of the hotter liquid increases by 20°F.

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24
Q 
Given the following parameters for an operating lube oil heat exchanger:
Lube oil inlet temperature = 150°F
Lube oil outlet temperature = 105°F
Cooling water inlet temperature = 60°F
Cooling water outlet temperature = 110°F
Considering only counter-flow and parallel-flow heat exchanger designs, the lube oil heat exchanger
described above must be…
A

counter-flow, because the lube oil outlet temperature is less than the cooling water outlet
temperature.

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25
Q

A reactor is shut down with core decay heat being removed by the residual heat removal (RHR)
system. Assume that only the RHR heat exchangers are removing heat from the reactor coolant
system (RCS), and that the RHR system provides complete thermal mixing of the RCS. Also, assume
that core decay heat is the only source of heat addition to the RCS.
Given the following information:
Reactor core rated thermal power = 2,950 MW
Core decay heat rate = 0.5% rated thermal power
RHR system heat removal rate = 5.3 x 107 Btu/hr
RHR and reactor coolant cp = 1.05 Btu/lbm-°F
Combined RCS and RHR inventory = 425,000 lbm
Which one of the following actions will establish a reactor cooldown rate between 20°F /hour and
30°F/hour?

A

Increase RHR heat exchanger flow rate to increase the cooldown rate by 20°F/hour.

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26
Q

A reactor is shut down with core decay heat being removed by the residual heat removal (RHR)
system. Assume that only the RHR heat exchangers are removing heat from the reactor coolant
system (RCS), and that the RHR system provides complete thermal mixing of the RCS. Also, assume
that core decay heat is the only source of heat addition to the RCS.
Given the following information:
Reactor core rated thermal power = 2,950 MW
Core decay heat rate = 0.5% rated thermal power
RHR system heat removal rate = 5.7 x 107 Btu/hr
RHR and reactor coolant cp = 1.05 Btu/lbm-°F
Combined RCS and RHR inventory = 450,000 lbm
Which one of the following actions will establish a reactor cooldown rate between 20°F/hour and
30°F/hour?

A

Increase RHR heat exchanger flow rate to increase the cooldown rate by 10°F/hour.

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27
Q

A reactor is shut down with core decay heat being removed by the residual heat removal (RHR)
system. Assume that only the RHR heat exchangers are removing heat from the reactor coolant
system (RCS), and that the RHR system provides complete thermal mixing of the RCS. Also, assume
that core decay heat is the only source of heat addition to the RCS.
Given the following information:
Reactor core rated thermal power = 2,950 MW
Core decay heat rate = 0.6 percent of rated thermal power
RHR system heat removal rate = 8.1 x 107 Btu/hr
RHR and reactor coolant cp = 1.05 Btu/lbm-°F
Combined RCS and RHR inventory = 450,000 lbm
Which one of the following actions will establish an RCS cooldown rate between 20°F/hour and
30°F/hour?

A

Reduce RHR heat exchanger flow rate to decrease the cooldown rate by 20°F/hour.

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28
Q

A reactor is shut down with the residual heat removal (RHR) system in service. Assume that only the
RHR heat exchangers are removing heat from the reactor coolant system (RCS), and the RHR system
provides complete thermal mixing of the RCS. Also, assume that core decay heat is the only source
of heat addition to the RCS.
Given the following current information:
Reactor core rated thermal power = 2,950 MW
Core decay heat rate = 0.6 percent of rated thermal power
RHR system heat removal rate = 4.7 x 107 Btu/hr
RHR and reactor coolant cp = 1.05 Btu/lbm-°F
Combined RCS and RHR coolant mass = 450,000 lbm
Which one of the following actions will establish a reactor coolant heatup rate between 10°F/hour and
20°F/hour?

A

Increase RHR heat exchanger flow rate to reduce the heatup rate by 10°F/hour

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29
Q

Refer to the drawing of an operating water cleanup system (see figure below).
All valves are identical and are initially 50 percent open. To lower the temperature at point 7, the
operator can adjust valve __________ in the open direction.

A

D

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30
Q

Refer to the drawing of an operating lube oil heat exchanger (see figure below).
Increasing the oil flow rate through the heat exchanger will cause the oil outlet temperature to
__________ and the cooling water outlet temperature to __________.

A

increase; increase

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31
Q

Refer to the drawing of an operating lube oil heat exchanger (see figure below).
Assume that the inlet lube oil and inlet cooling water temperatures are constant and cooling water flow
rate remains the same. Decreasing the oil flow rate through the heat exchanger will cause the lube oil
outlet temperature to __________ and the cooling water outlet temperature to __________.

A

decrease, decrease

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32
Q

Refer to the drawing of an operating water cleanup system (see figure below).
Valves A, B, and C are fully open. Valve D is 80 percent open. If valve D is throttled to 50 percent,
the temperature at point…

A

4 will increase.

33
Q

Refer to the drawing of an operating water cleanup system (see figure below).
Valves A, B, and C are fully open. Valve D is 20 percent open. If valve D is opened to 100 percent,
the temperature at point…

A

4 will decrease.

34
Q

Refer to the drawing of an operating water cleanup system (see figure below).
All valves are identical and are initially 50 percent open. To lower the temperature at point 4, the
operator can adjust valve __________ in the __________ direction.

A

B; close

35
Q

Refer to the drawing of a lube oil heat exchanger (see figure below).
The lube oil heat exchanger is in service with the following inlet temperatures:
Lube oil inlet temperature = 120°F
Cooling water inlet temperature = 60°F
Assuming that cooling water flow rate is greater than lube oil flow rate, which one of the following
pairs of heat exchanger outlet temperatures is possible? (Assume both fluids have the same specific
heat.)

A

Lube Oil Cooling Water
Outlet Temp Outlet Temp
80°F 80°F

36
Q

Refer to the drawing of a lube oil heat exchanger (see figure below).
The lube oil heat exchanger is in service with the following inlet temperatures:
Lube oil inlet temperature = 130°F
Cooling water inlet temperature = 70°F
Assuming that cooling water flow rate is greater than lube oil flow rate, which one of the following
pairs of heat exchanger outlet temperatures is possible? (Assume both fluids have the same specific
heat.)

A

Lube Oil Cooling Water
Outlet Temp Outlet Temp
90°F 100°F

37
Q

Refer to the drawing of a lube oil heat exchanger (see figure below).
The lube oil heat exchanger is in service with the following inlet temperatures:
Lube oil inlet temperature = 110°F
Cooling water inlet temperature = 75°F
Assuming that cooling water flow rate is greater than lube oil flow rate, which one of the following
pairs of heat exchanger outlet temperatures is possible? (Assume both fluids have the same specific
heat.)

A

Lube Oil Cooling Water
Outlet Temp Outlet Temp
90°F 90°F

38
Q

Refer to the drawing of an operating water cleanup system (see figure below).
All valves are identical and are initially 50 percent open. To raise the temperature at point 4, the
operator can adjust valve __________ in the __________ direction.

A

C; open

39
Q

Refer to the drawing of a lube oil heat exchanger (see figure below).
The lube oil heat exchanger is in service with the following inlet temperatures:
Lube oil inlet temperature = 130°F
Cooling water inlet temperature = 70°F
Assuming that cooling water flow rate is greater than lube oil flow rate, which one of the following
pairs of heat exchanger outlet temperatures is not possible? (Assume both fluids have the same
specific heat.)

A

Lube Oil Cooling Water
Outlet Temp Outlet Temp
120°F 83°F

40
Q 
Refer to the drawing of a lube oil heat exchanger (see figure below).
The lube oil heat exchanger is in service with the following inlet temperatures:
Lube oil inlet temperature = 130°F
Cooling water inlet temperature = 70°F
Assuming the cooling water flow rate exceeds the lube oil flow rate, which one of the following pairs
of heat exchanger outlet temperatures is possible? (Assume both fluids have the same specific heat.)
A

Lube Oil Cooling Water
Outlet Temp Outlet Temp
100°F 90°F

41
Q

Refer to the drawing of an operating water cleanup system (see figure below).
Valves A, B, and D are fully open and valve C is 50 percent open. If valve C is opened to 100 percent,
how will the temperatures at points 3 and 6 be affected?

A

Point 3 Point 6

Increase Increase

42
Q

Refer to the drawing of an operating water cleanup system (see figure below). All valves are identical
and are initially 50 percent open.
To raise the temperature at point 7, the operator can adjust valve _____ in the close direction.

A

D

43
Q

Refer to the drawing of a lube oil heat exchanger (see figure below).
The lube oil heat exchanger is in service with the following inlet temperatures:
Lube oil inlet temperature = 130°F
Cooling water inlet temperature = 70°F
Assume that cooling water mass flow rate is less than lube oil mass flow rate, and that both fluids have
the same specific heat. Which one of the following pairs of heat exchanger outlet temperatures is not
possible?

A

Lube Oil Cooling Water
Outlet Temp Outlet Temp
110°F 90°F

44
Q

Refer to the drawing of a lube oil heat exchanger (see figure below).
The lube oil heat exchanger is in service with the following inlet temperatures:
Lube oil inlet temperature = 120°F
Cooling water inlet temperature = 60°F
Assuming that cooling water flow rate is greater than lube oil flow rate, which one of the following
pairs of heat exchanger outlet temperatures is possible? (Assume both fluids have the same specific
heat.)

A

Lube Oil Cooling Water
Outlet Temp Outlet Temp
90°F 85°F

45
Q

Refer to the drawing of a lube oil heat exchanger (see figure below).
The lube oil heat exchanger is in service with the following inlet temperatures:
Lube oil inlet temperature = 130°F
Cooling water inlet temperature = 70°F
Given that cooling water mass flow rate is greater than lube oil mass flow rate, which one of the
following pairs of heat exchanger outlet temperatures is not possible? (Assume both fluids have the
same specific heat.)

A

Lube Oil Cooling Water
Outlet Temp Outlet Temp
110°F 95°F

46
Q

Refer to the drawing of an operating lube oil heat exchanger (see figure below).
Assume that the inlet lube oil and inlet cooling water temperatures are constant and the lube oil flow
rate remains the same. If the cooling water flow rate increases, the lube oil outlet temperature will
__________; and the cooling water outlet temperature will __________.

A

decrease; decrease

47
Q

Refer to the drawing of a heat exchanger (see figure below).
The heat exchanger is in service with the following inlet temperatures:
Service water inlet temperature = 130°F
Cooling water inlet temperature = 70°F
Assume that both fluids have the same specific heat, and that service water mass flow rate is greater
than cooling water mass flow rate. Which one of the following pairs of heat exchanger outlet
temperatures is possible?

A

Service Water Cooling Water
Outlet Temp Outlet Temp
120°F 82°F

48
Q

The heat exchanger is in service with the following inlet temperatures:
Cooling water inlet temperature = 70°F
Service water inlet temperature = 130°F
Assume that both fluids have the same specific heat, and that cooling water mass flow rate is greater
than service water mass flow rate. Which one of the following pairs of heat exchanger outlet
temperatures is not possible?

A

Service Water Cooling Water
Outlet Temp Outlet Temp
90°F 110°F

49
Q

Refer to the drawing of a heat exchanger (see figure below).
The heat exchanger is in service with the following inlet temperatures:
Service water inlet temperature = 130°F
Cooling water inlet temperature = 70°F
Assume that both fluids have the same specific heat, and that cooling water mass flow rate is greater
than service water mass flow rate. Which one of the following pairs of heat exchanger outlet
temperatures is possible?

A

Service Water Cooling Water
Outlet Temp Outlet Temp
90°F 105°F

50
Q

Severe stress in a mechanical component, induced by a sudden, unequally distributed temperature
reduction is a description of…

A

thermal shock.

51
Q

The major thermodynamic concern resulting from rapidly cooling a reactor vessel is…

A

thermal shock.

52
Q

Steam has been admitted to a main condenser for 25 minutes with no cooling water flow. Initiating
full cooling water flow rate at this time will…

A

induce large thermal stresses on the junctions between the condenser tubes and the tubesheet.

53
Q

Refer to the drawing of an operating lube oil heat exchanger (see figure below).
If scaling occurs inside the cooling water tubes, cooling water outlet temperature will __________;
and lube oil outlet temperature will __________. (Assume the lube oil and cooling water flow rates
do not change.)

A

decrease; increase

54
Q

Which one of the following will occur to reduce the heat transfer rate in a parallel-flow heat exchanger
as scaling increases on the exterior surface of the tubes?

A

Thermal conductivity of the tubes will decrease.

55
Q

A nuclear power plant is operating at steady-state conditions with the main generator supplying 1,000
MW to the power grid. Assume main generator load remains constant.
If one percent of the tubes in the main condenser become plugged, condenser absolute pressure will
__________; and condenser hotwell temperature will __________.

A

increase; increase

56
Q

Refer to the drawing of an operating lube oil heat exchanger (see figure below).
If deposits accumulate on the outside of the cooling water tubes, cooling water outlet temperature will
__________; and lube oil outlet temperature will __________. (Assume the lube oil and cooling
water inlet temperatures and mass flow rates do not change.)

A

decrease; increase

57
Q

A main turbine-generator is operating at 80 percent load with the following initial steady-state
temperatures for the main turbine lube oil heat exchanger:
Toil in = 174°F
Toil out = 114°F
Twater in = 85°F
Twater out = 115°F
After six months of main turbine-generator operation, the following final steady-state lube oil heat
exchanger temperatures are observed:
Toil in = 179°F
Toil out = 119°F
Twater in = 85°F
Twater out = 115°F
Assume the final cooling water and lube oil flow rates are the same as the initial flow rates, and the
specific heat values for the cooling water and lube oil do not change.
Which one of the following could be responsible for the differences between the initial and final heat
exchanger steady-state temperatures?

A

The heat exchanger tubes have become fouled with scale.

58
Q

Refer to the drawing of two system curves for a main condenser cooling water system (see figure
below).
Which one of the following will cause the system curve to shift from the solid curve toward the dashed
curve?

A

The main condenser tubes are cleaned.

59
Q

Refer to the drawing of two system curves for a typical main condenser cooling water system (see
figure below).
Which one of the following will cause the system curve to shift from the solid curve toward the dashed
curve?

A

The main condenser tubes become increasingly fouled

60
Q

Refer to the drawing of an operating lube oil heat exchanger (see figure below).
If mineral deposits accumulate on the inside of the cooling water tubes, cooling water outlet
temperature will __________; and lube oil outlet temperature will __________. (Assume the lube oil
and cooling water inlet temperatures and flow rates do not change.)

A

decrease; increase

61
Q

Refer to the drawing of an operating lube oil heat exchanger (see figure below).
The heat exchanger was initially placed in continuous service 6 months ago. During the 6-month
period of operation, mineral deposits have accumulated inside the heat exchanger tubes.
The following parameters are currently stable at their initial values:
• Lube oil mass flow rate
• Lube oil inlet temperature
• Lube oil outlet temperature
• Cooling water inlet temperature
Compared to their initial values, the current cooling water outlet temperature is __________; and the
current cooling water mass flow rate is __________.

A

lower; greater

62
Q

Refer to the drawing of an operating lube oil heat exchanger (see figure below).
The heat exchanger was initially placed in continuous service 6 months ago. During the 6-month
period of operation, mineral deposits have accumulated inside the heat exchanger tubes.
The following parameters are currently stable at their initial values:
• Cooling water mass flow rate
• Cooling water inlet temperature
• Cooling water outlet temperature
• Lube oil mass flow rate
Compared to their initial values, the current lube oil inlet temperature is __________; and the current
lube oil outlet temperature is __________.

A

higher; higher

63
Q

Borated water is flowing through the tubes of a heat exchanger being cooled by fresh water. The shell
side pressure is less than tube side pressure. What will occur as a result of a tube failure?

A

Shell side pressure will increase and the borated water inventory will be depleted.

64
Q

Refer to the drawing of an operating cooling water system (see figure below).
Which one of the following effects will occur because of the failed tube in the heat exchanger?

A

Low pressure (LP) fluid heat exchanger outlet temperature will decrease.

65
Q

A nuclear power plant is operating normally at 50 percent power. Which one of the following will
result from a cooling water tube rupture in the main condenser?

A

Increased conductivity of the condensate.

66
Q

With a nuclear power plant operating at 50 percent power, which one of the following will occur as a
result of multiple tube leaks in the main condenser? (Assume that main condenser vacuum does not
change.)

A

Condensate conductivity will increase.

67
Q

Refer to the drawing of an operating cooling water system (see figure below).
Which one of the following will occur as a result of the indicated tube failure in the heat exchanger?
(HP = high pressure; LP = low pressure)

A

Level in the surge tank will decrease.

68
Q

Initially, a nuclear power plant was operating at steady-state 100 percent power with the following
steam generator (SG) and reactor coolant system (RCS) parameters:
RCS average temperatures = 575°F
RCS hot leg temperatures = 600°F
RCS cold leg temperatures = 550°F
SG outlet steam pressures = 885 psig
Then, the reactor was shut down for a maintenance outage, during which multiple SG tube leaks were
discovered and plugged. After the outage, a total of 7 percent of the tubes in each SG were plugged.
The reactor was restarted and power was ramped to 100 percent. To establish a SG pressure of 885
psig at 100 percent power, the RCS average coolant temperatures will have to be increased to…

A

578°F

69
Q

Initially, a nuclear power plant was operating at steady-state 80 percent power with the following
steam generator (SG) and reactor coolant system (RCS) parameters:
RCS hot leg temperatures = 600°F
RCS cold leg temperatures = 550°F
RCS mass flow rate to each SG = 100 percent
Then, the reactor was shut down for a maintenance outage, during which multiple SG tube leaks were
discovered and then plugged. After the outage, the RCS mass flow rate to each SG was 98 percent.
When the reactor is once again operating at 80 percent power with RCS hot leg temperatures at 600°F,
the RCS cold leg temperatures will be…

A

549°F.

70
Q

A nuclear power plant was initially operating at steady-state 50 percent power with 50 gpm of main
condenser cooling water inleakage through a cooling water tube rupture. Power was then increased,
and is currently stable at 60 percent.
Assume the size of the cooling water tube rupture does not change, and the main condenser cooling
water inlet pressure and inlet temperature do not change.
When compared to the flow rate of main condenser cooling water inleakage at 50 percent power, the
flow rate of cooling water inleakage at 60 percent power is __________ because the main condenser
pressure at 60 percent power is __________.

A

lower; higher

71
Q

During normal nuclear power plant operation, a main condenser develops an air leak which decreases
vacuum at a rate of 1.0 inch Hg/min. Which one of the following will increase because of this
condition? (Assume that main turbine steam inlet valve position does not change.)

A

Condenser hotwell temperature.

72
Q

During normal nuclear power plant operation, why does air entry into the main condenser reduce the
thermodynamic efficiency of the steam cycle?

A

The enthalpy of the low pressure turbine exhaust increases.

73
Q

A nuclear power plant is operating at steady-state 100 percent power. Assume the main condenser
cooling water inlet temperature and flow rate do not change.
If the main condenser vacuum slowly decreases, the temperature of the condensate falling into the
hotwell will…

A

increase, because the condensate saturation pressure has increased.

74
Q

A nuclear power plant is operating at steady-state 100 percent power when air inleakage causes main
condenser vacuum to decrease from 28 inches Hg vacuum to 27 inches Hg vacuum. Assume the
main steam inlet pressure, inlet quality, and mass flow rate through the main turbine do not change,
and the condenser cooling water inlet temperature and mass flow rate do not change.
When the plant stabilizes, turbine exhaust quality will be __________; and turbine exhaust
temperature will be __________.

A

higher; higher

75
Q

A nuclear power plant is operating near rated power with the following initial conditions:
Main steam pressure = 900 psia
Main steam quality = 100 percent, saturated vapor
Main condenser pressure = 1.0 psia
Air leakage into the main condenser results in the main condenser pressure increasing and stabilizing
at 2.0 psia. Assume that all main steam parameters (e.g., pressure, quality, and mass flow rate)
remain the same and that the main turbine efficiency remains at 100 percent.
Which one of the following is the percent by which the main generator MW output will decrease as a
result of the main condenser pressure increase?

A

7.5 percent

76
Q

Refer to the drawing of an operating lube oil heat exchanger (see figure below).
The heat exchanger is operating with the following initial parameters:
Cooling water inlet temperature (Tcw-in) = 75°F
Cooling water outlet temperature (Tcw-out) = 95°F
Oil inlet temperature (Toil-in) = 150°F
Oil outlet temperature (Toil-out) = 120°F
Air introduction to the heat exchanger results in some of the heat exchanger tubes becoming
uncovered. As a result, Tcw-out decreases to 91°F. Assume the inlet temperatures, mass flow rates,
and specific heats of both fluids do not change.
Which one of the following will be the resulting temperature of the lube oil exiting the heat exchanger
(Toil-out)?

A

126°F

77
Q

Refer to the drawing of an operating lube oil heat exchanger (see figure below).
Given the following initial parameters:
Cooling water inlet temperature (Tcw-in) = 75°F
Cooling water outlet temperature (Tcw-out) = 105°F
Oil inlet temperature (Toil-in) = 140°F
Oil outlet temperature (Toil-out) = 100°F
Air introduction to the heat exchanger results in some of the heat exchanger tubes becoming
uncovered. As a result, Tcw-out decreases to 99F. Assume that the mass flow rate and specific heat
of both fluids remain the same, and that Toil-in does not change. Which one of the following will be
the approximate temperature of the lube oil exiting the heat exchanger (Toil-out)?

A

108°F

78
Q

Refer to the drawing of an operating lube oil heat exchanger (see figure below).
The heat exchanger is operating with the following initial parameters:
Cooling water inlet temperature (Tcw-in) = 75°F
Cooling water outlet temperature (Tcw-out) = 95°F
Oil inlet temperature (Toil-in) = 150°F
Oil outlet temperature (Toil-out) = 110°F
Air leakage into the heat exchanger causes some of the heat exchanger tubes to become uncovered.
As a result, Tcw-out decreases to 89°F. Assume the inlet temperatures, mass flow rates, and specific
heats of both fluids do not change.
Which one of the following will be the resulting temperature of the lube oil exiting the heat exchanger
(Toil-out)?

A

122°F

79
Q

Refer to the drawing of an operating lube oil heat exchanger (see figure below).
The heat exchanger was operating with the following initial parameters:
Cooling water inlet temperature (Tcw-in) = 71°F
Cooling water outlet temperature (Tcw-out) = 91°F
Oil inlet temperature (Toil-in) = 175°F
Oil outlet temperature (Toil-out) = 125°F
The heat exchanger was vented, resulting in the following current parameters:
Cooling water inlet temperature (Tcw-in) = 71°F
Cooling water outlet temperature (Tcw-out) = 95°F
Oil inlet temperature (Toil-in) = 175°F
Oil outlet temperature (Toil-out) = ?
Assume that the mass flow rates and specific heats of both fluids were unchanged.
Which one of the following is the current lube oil outlet temperature (Toil-out)

A

115°F

Components (3 decks)

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