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VIU PWR ENG Part B > Basic Concepts Of Compression and absorption Refrigeration > Flashcards

Basic Concepts Of Compression and absorption Refrigeration Flashcards

1
Q

A chemical dot placed under the lens of a sight glass that is exposed to liquid refrigerant monitors
Select one:
a. Liquid flow
b. Refrigerant levels
c. The presence of moisture in the refrigerant
d. Vapour flow

A

c. The presence of moisture in the refrigerant

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2
Q 
-744 is non-toxic and non-flammable. Which safety group does it belong to?
Select one:
a. Group A2 
b. Group B4  
c. Group A1 
d. Group A3
A

c. Group A1

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3
Q 
pressure relief device on a refrigeration system shall have sufficient capacity to prevent the pressure in the pressure vessel from rising more than \_\_\_\_\_ above the setting of the pressure relief device. 
Select one:
a. 10% 
b. 150%
c. 103 kPa
d. 25%
A

a. 10%

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4
Q

Refrigeration plant workers should never wear

Select one:

a. Cotton clothing
b. Long sleeve shirts
c. Contact lenses
d. Latex gloves

A

c. Contact lenses

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5
Q

Absorption refrigeration systems may use waste in order to
Select one:
a. pressurize the system
b. evaporate water from the weak lithium bromide
c. decrease the evaporation point of the refrigerant
d. maintain a minimum load on the system, during periods of low cooling demand
e. To increase the lithium boiling point.

A

b. evaporate water from the weak lithium bromide

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6
Q 
The CSA B52 code requires that \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ shall be provided on all systems operating above atmospheric pressure. 
Select one:
a. pressure limiting devices  
b. temperature cutout devices 
c. flow switches
d. purgers
A

a. pressure limiting devices

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7
Q

Pressure limiting devices must shut down the pressure imposing element at ___________% of the high side design pressure.

Select one:

a. 80%
b. 90%
c. 110%
d. 100%

A

b. 90%

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8
Q

Which of the following is NOT an advantage of a factory assembled, packaged refrigeration unit?
Select one:
a. Components are designed to match each other
b. The final installation does not need to meet CSA B52 code
c. The unit is equipped with all the required auxiliary equipment
d. The unit is factory tested in operation

A

b. The final installation does not need to meet CSA B52 code

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9
Q 
Which of the following is not a component of a closed cycle compression refrigeration system? 
Select one:
a. Evaporator 
b. Compressor 
c. Absorber  
d. Condenser
A

c. Absorber

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10
Q 
A safety control designed to protect the chiller from freezing is the: 
Select one:
a. Vane closed switch 
b. Low oil pressure shut down switch 
c. Motor demand limiter 
d. Chilled water flow switch
A

d. Chilled water flow switch

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11
Q 
Which of the following is NOT a form of refrigeration evaporator construction? 
Select one:
a. Bare tube 
b. Plate surface 
c. Shell and tube  
d. Finned tube 
e. Double-tube
A

e. Double-tube

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12
Q

The low oil pressure cut-off switches of a mechanical refrigeration system
Select one:
a. keep the compressor oil pressure at a level where the oil will not freeze
b. prevent compressor start-up if the oil heater fails
c. shut down the compressor when the oil pressure drops below the minimum required value
d. keep the oil from gelling at low pressure

A

c. shut down the compressor when the oil pressure drops below the minimum required value

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13
Q 
Which of the following is NOT a common type of refrigeration condenser? 
Select one:
a. Flooded 
b. Air-cooled  
c. Shell and tube 
d. Shell and coil
A

a. Flooded

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14
Q 
Which of the following is an example of a loss of latent heat? 
Select one:
a. Steam condenses  
b. Water evaporates 
c. Ice melts 
d. Refrigerant evaporates
A

a. Steam condenses

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15
Q

With regard to economizers installed on packaged air-conditioning chillers, which of the following statements is FALSE?
Select one:
a. Economizers control the flow of liquid refrigerant from the evaporator to the condenser
b. Liquid refrigerant levels in each chamber are controlled by float operated valves
c. The upper float chamber is connected to the bottom of the condenser
d. The economizer is made of two chambers

A

a. Economizers control the flow of liquid refrigerant from the evaporator to the condenser

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16
Q

In a closed vessel, the boiling point of a liquid can be raised by:
Select one:
a. Raising the liquid level in the vessel
b. Lowering the pressure in the vessel
c. Raising the pressure in the vessel
d. Decreasing the temperature in the vessel

A

c. Raising the pressure in the vessel

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17
Q

The net refrigerating effect of a refrigerant is the amount of heat:
Select one:
a. Discharged by the condenser
b. Absorbed by the refrigerant in the evaporator
c. Added to the refrigerant by the compressor
d. Discharged by the refrigerant in the evaporator

A

b. Absorbed by the refrigerant in the evaporator

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18
Q 
A compression refrigeration system can be divided into two sections: a high pressure section containing the head pressure and a low pressure section carrying the \_\_\_\_\_ pressure: 
Select one:
a. Discharge 
b. Saturation
c. Absolute
d. Suction
A

d. Suction

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19
Q 
The refrigerant R-134a belongs to the following safety group: 
Select one:
a. A2
b. B1 
c. A3
d. A1
A

d. A1

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20
Q

Which of the following is NOT a function of the refrigeration compressor?
Select one:
a. Raises the pressure of the refrigerant
b. Raises the temperature of the refrigerant
c. Maintains a low pressure in the evaporator
d. Removes energy from the vapour

A

d. Removes energy from the vapour

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21
Q

Ammonia piping (according to IIAR), should be labelled in:

Select one:

a. Yellow background with black letters
b. Red background with white letters
c. Orange background with white letters
d. Orange background with black letters

A

d. Orange background with black letters

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22
Q 
One tonne of refrigeration is: 
Select one:
a. 13958 kJ per day 
b. 1000 kg of mass 
c. 233 kJ per minute 
d. 13958 J per hour
A

c. 233 kJ per minute

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23
Q 
The accessory that maintains efficient heat transfer by collecting oil before it coats the tubes of the condenser is called: 
Select one:
a. A filter-drier 
b. An oil scrubber 
c. An adsorber
d. An oil separator
A

d. An oil separator

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24
Q

All refrigeration evaporators:
Select one:
a. require regular defrosting
b. are part of the high side of the system
c. are located between the expansion valve and the king valve.
d. are flooded with refrigerant
e. boil liquid refrigerant at low pressure and low temperature

A

e. boil liquid refrigerant at low pressure and low temperature

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25
Q 
The most widely used refrigerant metering device, which consists of a pressure-sensitive bellows or diaphragm connected to a temperature sensing bulb, is the 
Select one:
a. thermostatic expansion valve 
b. automatic expansion valve 
c. capillary tube  
d. manual expansion valve
A

a. thermostatic expansion valve

26
Q

Moisture in a refrigeration system will NOT cause
Select one:
a. The formation of ice inside the refrigeration system.
b. Acid formation inside the refrigeration system.
c. The deterioration of the motor insulation of a hermetic compressor.
d. Excessive high-side pressures.

A

d. Excessive high-side pressures

27
Q

The safety head of a refrigeration compressor is designed to:
Select one:
a. Unload cylinders if over-loaded
b. Relieve pressure due to liquid in the cylinder
c. Prevent damage due to freeze-up
d. Take the place of a safety relief valve

A

b. Relieve pressure due to liquid in the cylinder

28
Q

Which of the following statements about the shell and tube evaporator is FALSE?
Select one:
a. A shell and tube evaporator is also called a chiller.
b. In a direct expansion chiller, the brine circulates through the tubes.
c. In the flooded chiller, the refrigerant is contained in the shell, and surrounds the tubes.
d. Refrigerant vapour is drawn from the evaporator by the compressor.

A

b. In a direct expansion chiller, the brine circulates through the tubes.

29
Q 
If the first column of a refrigeration table lists the saturation temperature of a refrigerant, which column will most likely list the saturation pressure? 
Select one:
a. Column 1  
b. Column 2 
c. Column 3 
d. Column 4
A

b. Column 2

30
Q 
The saturation temperature of a refrigerant is the same as its:  
Select one:
a. Boiling point   
b. Freezing point  
c. Saturation pressure 
d. Fire point
A

a. Boiling point

31
Q 
Of the following refrigeration system evaporators, the \_\_\_\_\_\_\_\_\_\_\_ evaporators require the largest refrigerant charge. 
Select one:
a. Direct expansion 
b. Bare tube 
c. Plate surface 
d. Flooded  
e. Finned tube
A

d. Flooded

32
Q 
Which of the following is not found on the low side of an ammonia absorption refrigeration system? 
Select one:
a. Evaporator 
b. Generator
c. Absorber
d. Low pressure ammonia vapour
A

b. Generator

33
Q

With regard to a refrigeration system pressurestat, which of the following statements is FALSE?
Select one:
a. The control is connected to the suction line of the compressor
b. The control consists of a switch actuated through a linkage arrangement connected to a bellows or diaphragm
c. A pressurestat should be used in conjunction with an automatic expansion valve
d. When the pressure drops to the minimum allowable the switch acts opposite to a thermostat and opens

A

c. A pressurestat should be used in conjunction with an automatic expansion valve

34
Q

The ideal refrigerant should:
Select one:
a. Have a high boiling point at atmospheric pressure.
b. Have high condensing pressure
c. Have a low ozone depleting potential and a low global warming potential
d. Have a low latent heat capacity

A

c. Have a low ozone depleting potential and a low global warming potential

35
Q 
A direct expansion type evaporator that has more than one refrigerant circuit requires \_\_\_\_\_\_\_\_\_\_ to provide even refrigerant flow in each circuit. 
Select one:
a. An expansion valve 
b. A distributor 
c. A purge valve 
d. A backpressure regulator
A

b. A distributor

36
Q

Which of these statements about automatic expansion valves is FALSE?
Select one:
a. The automatic expansion valve maintains constant evaporator pressure, while the compressor is operating, regardless of the load.
b. The automatic expansion valve is usually used with multiple cooling coils connected to the same compressor.
c. A spring exerting a downward force on the diaphragm tends to open the automatic expansion valve.
d. When the compressor stops, the valve automatically closes.

A

b. The automatic expansion valve is usually used with multiple cooling coils connected to the same compressor.

37
Q

To drain oil from an NH3 system, a special self-closing __________ valve may be installed as a safety feature.

Select one:

a. Butterfly
b. Safety shut-off
c. Check
d. Dead man

A

d. Dead man

38
Q 
In an Ammonia Absorption refrigeration system, what is used as the absorbent? 
Select one:
a. Ammonia 
b. Lithium Bromide 
c. Water  
d. R-717
A

c. Water

39
Q 
When a liquid evaporates, it 
Select one:
a. Gains sensible heat 
b. Gains latent heat  
c. Loses sensible heat 
d. Loses latent heat
A

b. Gains latent heat

40
Q 
Which of the following is NOT a physical property of refrigerants? 
Select one:
a. Saturation temperature
b. Leakage tendency  
c. Corrosiveness 
d. Miscibility
A

c. Corrosiveness

41
Q

Which of the following statements about strainers is false?
Select one:
a. Strainers prevent foreign particles from damaging compressor valves.
b. Piping must be disconnected to clean the strainer.
c. Hermetic type compressors are equipped with a built-in suction strainer.
d. Strainers typically consist of a fine mesh screen basket.

A

b. Piping must be disconnected to clean the strainer.

42
Q 
Heat that causes an increase in temperature, is called \_\_\_\_\_ heat: 
Select one:
a. Radiant 
b. Sensible  
c. Latent 
d. Convective
A

b. Sensible

43
Q 
R-134a
Select one:
a. is non-toxic  
b. has a strong, pungent odour
c. is explosive when mixed with air
d. is an ozone-depleting substance
A

a. is non-toxic

44
Q

What must be located outside a Class T machinery room?

Select one:

a. Machinery shut off switch
b. Disposable coveralls
c. Spare flashlights
d. Light switches

A

a. Machinery shut off switch

45
Q 
An evaporator that can easily be cleaned and defrosted manually without interrupting the cooling process is which type of evaporator? 
Select one:
a. Liquid recirculating evaporator 
b. Finned evaporator  
c. Plate surface evaporator 
d. Shell and tube evaporator
A

c. Plate surface evaporator

46
Q 
A sulfur candle is used to test for 
Select one:
a. R-744 leaks 
b. R-717 leaks  
c. R-290 leaks
d. CFC leaks
A

b. R-717 leaks

47
Q

Positive pressure testing of a new refrigeration system may be done
Select one:
a. by pressurizing the system with the compressor
b. by filling the system with oxygen, and then checking for leaks
c. by filling the system with an inert gas, and then performing a soap bubble test.
d. by performing a hydrostatic test, using softened water

A

c. by filling the system with an inert gas, and then performing a soap bubble test.

48
Q 
The refrigeration condenser design that requires chemical cleaning, because it cannot be mechanically cleaned, is the: 
Select one:
a. Shell and tube condenser
b. Shell and coil condenser 
c. Air-cooled condenser
d. Evaporative condenser
A

b. Shell and coil condenser

49
Q

The function of the condenser in a refrigeration system is to:
Select one:
a. Lower the temperature of the liquid refrigerant
b. Change high pressure refrigerant vapour to liquid
c. Lower the temperature of the refrigerant vapour
d. Lower the liquid refrigerant pressure

A

b. Change high pressure refrigerant vapour to liquid

50
Q

Which of the following statements about double tube refrigeration condensers is true?
Select one:
a. They consist of two separate tubes side by side.
b. They are easy to clean.
c. Water flows in the inner tube in the opposite direction of the flow of refrigerant.
d. They are the most efficient of all condensers.

A

c. Water flows in the inner tube in the opposite direction of the flow of refrigerant.

51
Q 
In a lithium bromide refrigeration system, which of the following is the refrigerant?
Select one:
a. Lithium bromide
b. Lithium solution
c. Water 
d. Aqueous bromine
A

c. Water

52
Q

The expansion valve in a refrigeration system
Select one:
a. Expands the liquid to the receiver
b. Regulates the liquid refrigerant flow to the evaporator
c. Is used to charge the refrigeration system
d. Isolates the compressor from the condenser

A

b. Regulates the liquid refrigerant flow to the evaporator

53
Q

Which of the following steps is NOT part of a start-up of a reciprocating or rotary compressor refrigerating system?
Select one:
a. Check for proper oil level in the compressor
b. Open shutoff valves in the cooling water supply and return lines of water-cooled condensers
c. Valves in pressure piping should be closed
d. Check the setting of high and low pressure cut-off switches

A

c. Valves in pressure piping should be closed

54
Q

In the lithium bromide refrigeration system, what is the function of the concentrator (generator)?
Select one:
a. To exchange heat between the high temperature refrigerant vapour and the atmosphere
b. To increase the absorbency potential of used absorbent
c. To speed up the evaporation of the refrigerant
d. To cool the concentrated absorbent

A

b. To increase the absorbency potential of used absorbent

55
Q 
A liquid trap located in the suction line before a refrigeration compressor, which evaporates liquid refrigerant and returns it to the compressor as a gas, is called: 
Select one:
a. An oil separator 
b. A strainer-drier  
c. A distributor 
d. An accumulator
A

d. An accumulator

56
Q 
When a chiller has stopped due to low water temperature, and the chilled water temperature subsequently rises approximately 5 to 6°C above the chilled water temperature set point, the: 
Select one:
a. Compressor will restart  
b. Compressor will unload 
c. Cooling tower fan will restart 
d. Condenser pump will restart
A

a. Compressor will restart

57
Q 
The rate at which a refrigeration system removes heat from the refrigerated medium is defined as: 
Select one:
a. the Coefficient of Performance
b. the Net Cooling Effect
c. the refrigeration capacity. 
d. the Compression Ratio
A

c. the refrigeration capacity.

58
Q

Refrigerant compressors:
Select one:
a. Must have intercoolers
b. Could be the centrifugal type
c. Use automotive-style suction and discharge valves
d. Have more cooling fins than air compressors

A

b. Could be the centrifugal type

59
Q 
In a refrigeration system, the liquid refrigerant is changed to a gas in the: 
Select one:
a. Condenser 
b. Receiver 
c. Compressor 
d. Evaporator
A

d. Evaporator

60
Q 
In order to lower the boiling point of the refrigerant in the lithium bromide refrigeration system, it is important that the system maintain 
Select one:
a. An extremely high vacuum  
b. Very high pressure 
c. Very low temperatures 
d. High absorbent circulation rates
A

a. An extremely high vacuum

VIU PWR ENG Part B (18 decks)

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