Quiz 21
What are some typical problems on the liquid side of a liquid cooling evaporator?
- float mechanical fails - too much air in the system - mineral deposits - leaks - not all refrigerant is liquid
Low temperature food storage applications generally start at _______.
0 degrees F
As a rule of thumb, the temperature of the evaporator should be about _______ degrees F colder than the box temperature.
15
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?
25 psig
The household refrigerator fresh-food compartment typically ranges from_____.
28 to 40 degrees F
A typical evaporator operating temperature in an air-conditioning system is _________.
40 degrees F
High-temperature refrigeration applications will normally provide box temperatures of ________.
47 to 60 degrees F
A typical superheat for an evaporator operating under normal conditions would be________.
8 to 12 degrees F
Describe a flooded coil
A flooded coil is when you have a low superheat and possibly be overcharged.
_________ the air means to remove the moisture, and this is frequently desirable in refrigeration systems.
Dehumidifier
T/F: Every central split cooling system manufactured in the USA today must have a Seasonal Energy Efficiency Ratio (SEER) of at least 10.
False
What is a starved coil?
Is when you have a high superheat. Also restriction or being under charged could be present
________ -temperature refrigeration produces temperature below the freezing point of water
Low
What do temperature ranges for commercial refrigeration refer to?
Low, medium, high
__________ evaporators are used when the coil would become too long for a single circuit, percent vapor
Multiple circuit
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 _________.
Refrigeration
_________ is the best method of checking to see when a refrigerant coil has a proper level of refrigerant.
Superheat
T/F: A stamped plate evaporator usually does not use a fan to move air across it
True
T/F: The capacity (tonnage) of heat exchanger can vary with its height and depth
True
T/F: The film factor is a relationship between the medium giving up heat and the heat-exchange surfaces.
True
T/F: The refrigeration evaporator is a component that absorbs heat from the conditioned space into the refrigeration system.
True
T/F: 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
What is a bearing washout?
When there's low oil level in the crankcase
Why are the fins of a low temperature evaporator spaced wider apart than those on a high temperature evaporator?
because the fins will accumulate ice. With the fins being wider it will allow the ice to form, but will not cause restriction to the coil.
The_______ of the liquid refrigerant determines the coil operating temperature
boiling temperature
If the application requires a coil design to operate below freezing, there must be provision for_________.
defrost
A direct expansion-type evaporator is also called a ________.
dry-type evaporator
The _______ in a refrigeration system is responsible for absorbing heat into the system from whatever medium is to be cooled.
evaporator
The boiling temperature and its relationship to the system exist in the _______.
evaporator
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 ________.
flooded evaporators
A refrigeration system designed for the storage of flowers or candy is considered a _______ type.
high temperature
A defrost system that pipes the compressor discharge vapor directly to the evaporator is called a (n) ________ type.
hot gas
Define superheat.
is the best method of checking to see when a refrigerant coil has a proper level of refrigerant. Also when the refrigerant vapor is saturated with heat.
Define saturated vapor.
is when all the liquid has been boiled off into a vapor.
The household refrigerator fresh-food compartment is a good example of _______ refrigeration.
medium-temperature
When the refrigerant vapor is saturated with heat it is known as a(n) _______.
saturated vapor
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.
watt hours