WorksheetsACR-104 UNIT 21 END OF UNIT TEST
Total questions: 35
Worksheet time: 30mins
The process of removing heat from a place where it is not wanted and transferring that heat to a place where it makes little or no difference is known as _____.
cooling
refrigeration
defrosting
temperature balancing
The household refrigerator fresh-food compartment is a good example of _____ refrigeration.
low-temperature
medium-temperature
high-temperature
average-temperature
The household refrigerator fresh-food compartment typically ranges from _____.
25 to 35°F
28 to 40°F
30 to 42°F
32 to 45°F
Low-temperature food storage applications generally start at _____.
-20°F
0°F
32°F
40°F
High-temperature refrigeration applications will normally provide box temperatures of _____.
20 to 40°F
32 to 50°F
47 to 60°F
50 to 67°F
A refrigeration system designed for the storage of flowers or candy is considered a _____ type.
high temperature
medium temperature
low temperature
sharp freezing
The _____ in a refrigeration system is responsible for absorbing heat into the system from whatever medium is to be cooled.
evaporator
thermostat
compressor
condenser
The boiling temperature and its relationship to the system exist in the _____.
coil
thermostat
condenser
evaporator
A typical evaporator operating temperature in an air-conditioning system is ____.
40°F
55°F
75°F
200°F
The _____ of the liquid refrigerant determines the coil operating temperature.
freezing point
melting point
transition temperature
boiling temperature
If an evaporator has a pressure drop of 10 psig and the low side pressure is 15 psig, what is the pressure at the inlet of the evaporator?
5 psig
10 psig
15 psig
25 psig
Evaporators that are operated full of liquid and are equipped with a device to keep the liquid refrigerant from passing to the compressor are known as _____.
locked evaporators
seized evaporators
flooded evaporators
stoned evaporators
A direct expansion-type evaporator is also called a _____.
flooded evaporator
dry-type evaporator
multi-circuit evaporator
stamped evaporator
_____ is the best method of checking to see when a refrigerant coil has a proper level of refrigerant.
Boiling temperature
Superheat
Dryheat
Vapor temperature
A typical superheat for an evaporator operating under normal conditions would be _____.
4 to 6°F
6 to 8°F
8 to 12°F
14 to 16°F
If the application requires a coil design to operate below freezing, there must be provision for ____.
flooding the evaporator
adding refrigerant
defrost
suction pressure control
The refrigeration evaporator is a component that absorbs heat from the conditioned space into the refrigeration system.
True
False
The film factor is a relationship between the medium giving up heat and the heat-exchange surface.
True
False
A stamped plate evaporator usually does not use a fan to move air across it.
True
False
The capacity (tonnage) of the heat exchanger can vary with its height and depth.
True
False
Every central split cooling system manufactured in the USA today must have a Seasonal Energy Efficiency Ratio (SEER) of at least 10.
True
False
To check the performance of a dry-type evaporator, the service technician would first make sure that the refrigerant coil is operating with enough liquid inside.
True
False
temperature refrigeration produces temperatures below the freezing point of water.
As a rule of thumb, the temperature of the evaporator should be about °F colder than the box temperature.
the air means to remove the moisture, and this is frequently desirable in refrigeration systems.
SEER is calculated based on the total amount of cooling the system will provide over the entire season, divided by the total number of it will consume.
When the refrigerant vapor is saturated with heat it is known as a(n) .
(a) evaporators are used when the coil would become too long for a single circuit, percent vapor.
A defrost system that pipes the compressor discharge vapor directly to the evaporator is called a type.
What is the definition of saturated vapor?
Saturated vapor has been cooled to its condensing temperature but has not given up any latent heat
A vapor that is completely dry and contains no liquid particles.
A vapor that is at a temperature below its boiling point.
A vapor that is mixed with other gases.
Superheat is the added to the vapor refrigerant after the change of state has occurred.
Superheat is the sensible heat added to the vapor refrigerant after the change of state has occurred.
Superheat is the latent heat added to the vapor refrigerant after the change of state has occurred.
Superheat is the pressure added to the vapor refrigerant after the change of state has occurred.
Superheat is the volume added to the vapor refrigerant after the change of state has occurred.
What is a starved coil?
A coil with insufficient refrigerant flow
A coil with excess refrigerant flow
A coil operating at optimal conditions
A coil that is not functioning at all
What is a flooded coil?
A coil that operates with too much refrigerant
A coil that operates with air partially filling the tubes
A coil that operates with water partially filling the tubes
A coil that operates with oil completely filling the tubes
What are some typical problems on the liquid side of a liquid cooling evaporator?
Mineral deposits build up leading to poor heat exchange
Excessive cooling
High pressure
Low refrigerant flow
Why are the fins of a low temperature evaporator spaced wider apart than those on a high temperature evaporator?
To allow for more efficient heat transfer at low temperatures.
To allow for the formation of frost without blocking air flow.
To reduce the cost of manufacturing the evaporator.
To increase the surface area for heat exchange.
