Short Answer
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1.
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What
is the subcooling if my Head Pressure is 500 psig and my refrigerant outlet temp is 92.
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2.
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In
the previous question is the subcooling normal, and if it isn’t, what is the
problem?
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3.
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In a
tube-in-tube condenser, the refrigerant flows in the outer tube and the water flows in the inner
tube. Why?
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4.
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Describe the term "counterflow" when used to describe the flow through a
tube-in-tube condenser.
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5.
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What
would the symptom be if an air-cooled condenser had two fans and one stopped running?
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6.
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Define "desuperheat."
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7.
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What
is the condenser saturation temperature if there is 20°F of subcooling and the outlet
temperature of the refrigerant is 90°F?
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8.
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What
is meant by the term "blow down"?
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9.
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Define "heat reclaim."
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10.
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Define "subcooling."
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11.
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What
can you do to insure that a system is as efficient as possible and last as long as
possible?
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12.
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What
is another name for a Shell and Coil condenser?
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Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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13.
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If
the waterflow is reduced, the temperature difference across a condenser will ____. a. | increase | b. | remain the same | c. | decrease | d. | correspond to the evaporator saturation
temperature | | |
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14.
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A
normally operating water-cooled condenser is operating with a 10° differential between water in
and water out. If the amount of 85°F water going through the condenser is reduced, which of the
following is a possible temperature of the water leaving the condenser?
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15.
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Which
of the following would allow a system to operate more efficiently? a. | condenser that
had refrigerant leaving with 10°F of superheat | b. | condenser that
had refrigerant leaving with 10° of subcooling | c. | condenser that
had refrigerant leaving with 15° of subcooling | d. | condenser that
had refrigerant leaving as 100% vapor | | |
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16.
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If an
R-12 refrigeration system has its air-cooled condensing unit on a 100°F roof and the condenser
outlet temperature (refrigerant) is 115°F, with how much subcooling is the condenser
operating? a. | 130°F | b. | 30°F | c. | 100°F | d. | 15°F | | |
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17.
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Mineral deposits in the water portion of a water-cooled condenser act as
____. a. | an
insulator | b. | They have no effect on the operation of the
condenser. | c. | a conductor of heat | d. | a cleaning
solution | | |
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18.
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What
can be used to maintain the head pressure of a system with a water-cooled condenser? a. | fan
cycling | b. | dampers or louvers | c. | water regulating
valve | d. | all of the above | | |
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19.
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The
water circuit in shell and coil and coil-type tube-in-a-tube condensers must be cleaned
____. a. | by air
pressure | b. | with a brush | c. | chemically | d. | by removing the end caps | | |
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20.
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In a
water-cooled condenser with dirty condenser tubes, the temperature difference between the refrigerant
and the leaving water will be ____ when the tubes are clean. a. | slightly lower
than | b. | less
than | c. | the same
as | d. | greater
than | | |
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21.
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The
shell and tube condenser is cleaned ____. a. | with a brush after removing the end
caps | b. | only with
chemicals | c. | with compressed air | d. | with a vacuum
cleaner | | |
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22.
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The
refrigerant in a condenser in a refrigeration system ____. a. | is under lower
pressure than the evaporator | b. | changes to a vapor | c. | absorbs
heat | d. | gives up
heat | | |
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23.
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Which
of the following can be used to maintain the head pressure of a system with an air-cooled
condenser? a. | condenser
flooding valve | b. | dampers or louvers | c. | fan
cycling | d. | all of the above | | |
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24.
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An
air-cooled condenser that is operating in a climate that has four distinct seasons must
____. a. | operate with
zero degrees of subcooling | b. | use a water regulating valve | c. | have some type
of head pressure control | d. | have a multi-circuit evaporator | | |
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25.
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Control of the head pressure in an air-cooled condenser is done by
____. a. | controlling
dampers in the airstream through the condenser | b. | flooding the
condenser with refrigerant | c. | cycling the condenser fan | d. | all of the
above | | |
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26.
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Condensing temperatures in an air-cooled condensing unit can be reduced by
____. a. | increasing the
condensing surface area | b. | increasing the cfm through the
condenser | c. | decreasing the temperature of the air entering the
condenser | d. | all of the above | | |
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27.
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In a
water-cooled condenser, a regulating valve is used to control the ____. a. | suction
pressure | b. | refrigerant condensing pressure | c. | refrigerant flow
through the pressure reducing device | d. | refrigerant condensing temperature | | |
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28.
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When
a system with a water-cooled condenser cycles off, the water regulating valve should
____. a. | remain open
during the off cycle | b. | open all the way | c. | re-calibrate
itself to maintain the new lower head pressure | d. | close, since the
head pressure is lower | | |
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29.
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The
condenser in a refrigeration system ____. a. | desuperheats the vapor from the
compressor | b. | subcools the liquid refrigerant before it leaves the
condenser | c. | condenses the vapor from the
compressor | d. | all of the above | | |
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30.
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Which
of the following condensers is the most efficient? a. | forced draft
air-cooled | b. | induced draft air-cooled | c. | water-cooled
parallel flow | d. | water-cooled counter flow | | |
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31.
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A
normally operating water-cooled condenser is operating with a 10° differential between water in
and water out. If scale forms on the water tubes and the entering water is 85°F, which of the
following is possible? a. | The outlet water will be 88°F. | b. | The system head
pressure will rise. | c. | The water regulating valve will
close. | d. | Both a and b are correct. | | |
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True/False
Indicate whether the sentence or statement is true
or false.
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32.
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A
water regulating valve helps to maintain a system's head pressure by modulating the flow of
refrigerant through the condenser.
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33.
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The
desired water flow through a condenser connected to a recirculating water system is 1.5 gallons per
minute.
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34.
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If
the spring pressure of a water regulating valve is increased, the system head pressure will also
decrease.
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35.
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Evaporative condensers operate more efficiently in climates where the wet bulb
temperature is a great deal lower than the dry bulb temperature.
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Completion
Complete each sentence or
statement.
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36.
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The
low form of plant life that grows in condenser water is ____________________.
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37.
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In
order for a flooded condenser type head pressure control system to operate, a device called a
____________________ has to be added to the system because of the extra refrigerant.
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38.
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If an
air-cooled condenser's fan motor stops running, the head pressure will ____________________and the
amount of subcooling will ____________________.
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39.
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In a
water-cooled condenser, the leaving water temperature is normally ____________________°F lower
than the condensing temperature of the refrigerant.
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40.
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An
evaporative condenser uses ____________________ and ____________________ as the transfer medium for
system heat.
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