WorksheetsACR 104 Midterm
Total questions: 53
Worksheet time: 27mins
Name
Class
Date
1.
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 ____.
a)
refrigeration
b)
cooling
c)
defrosting
d)
temperature balancing
2.
The household refrigerator fresh-food compartment typically ranges from ____.
a)
28 to 40°F
b)
25 to 35°F
c)
30 to 42°F
d)
32 to 45°F
3.
Low-temperature food storage applications generally start at ____.
a)
0°F
b)
-20°F
c)
32°F
d)
40°F
4.
High-temperature refrigeration applications will normally provide box temperatures of ____.
a)
47 to 60°F
b)
32 to 50°F
c)
20 to 40°F
d)
50 to 67°F
5.
A refrigeration system designed for the storage of flowers or candy is considered a ____ type.
a)
high temperature
b)
medium temperature
c)
low temperature
d)
sharp freezing
6.
The ____ in a refrigeration system is responsible for absorbing heat into the system from whatever medium is to be cooled.
a)
evaporator
b)
thermostat
c)
compressor
d)
condenser
7.
The boiling temperature and its relationship to the system exist in the ____.
a)
evaporator
b)
coil
c)
compressor
d)
condenser
8.
A typical evaporator operating temperature in an air-conditioning system is ____.
a)
40°F
b)
55°F
c)
75°F
d)
200°F
9.
The ____ of the liquid refrigerant determines the coil operating temperature.
a)
boiling temperature
b)
freezing point
c)
melting point
d)
transition temperature
10.
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?
a)
25 psig
b)
5 psig
c)
10 psig
d)
15 psig
11.
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 ____.
a)
flooded evaporators
b)
locked evaporators
c)
seized evaporators
d)
stoned evaporators
12.
A direct expansion-type evaporator is also called a ____.
a)
dry-type evaporator
b)
flooded evaporator
c)
multi-circuit evaporator
d)
stamped evaporator
13.
____ is the best method of checking to see when a refrigerant coil has a proper level of refrigerant.
a)
Superheat
b)
Dryheat
c)
Boiling temperature
d)
Vapor temperature
14.
A typical superheat for an evaporator operating under normal conditions would be ____.
a)
8 to 12°F
b)
4 to 6°F
c)
6 to 8°F
d)
14 to 16°F
15.
If the application requires a coil design to operate below freezing, there must be provision for ____.
a)
defrost
b)
flooding the evaporator
c)
adding refrigerant
d)
suction pressure control
16.
The film factor is a relationship between the medium giving up heat and the heat-exchange surface.
a)
True
b)
False
17.
A stamped plate evaporator usually does not use a fan to move air across it.
a)
True
b)
False
18.
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.
a)
True
b)
False
19.
____________________-temperature refrigeration produces temperatures below the freezing point of water.
a)
Low
b)
High
c)
Medium
d)
Neutral
20.
As a rule of thumb, the temperature of the evaporator should be about ____________________°F colder than the box temperature.
a)
15
b)
16
c)
20
d)
14
21.
___________________ the air means to remove the moisture, and this is frequently desirable in refrigeration systems.
a)
Dehumidifying
b)
Humidifying
c)
Heating
d)
Cooling
22.
When the refrigerant vapor is saturated with heat it is known as a(n) ____________________.
a)
Saturated vapor
b)
Saturated liquid
c)
Boiling point
d)
Humidified vapor
23.
____________________ evaporators are used when the coil would become too long for a single circuit, percent vapor.
a)
Multi-circuit
b)
Single-circuit
c)
Double-circuit
d)
Variable-circuit
24.
A defrost system that pipes the compressor discharge vapor directly to the evaporator is called a(n)
a)
Hot gas defrost
b)
Defrost
c)
Accumulated Moisture defrost
d)
Heat defrost
25.
Define saturated vapor.
a)
Saturated vapor has been cooled to its condensing temperature but has not given up any latent heat
b)
Saturated vapor has been heated to its condensing temperature but has not given up any latent heat
c)
Saturated vapor has been cooled to its condensing temperature but has given up its latent heat
d)
Saturated vapor has been cooled to its condensing temperature but has not given up any sensible heat
26.
Define superheat.
a)
Superheat is the sensible heat added to the vapor refrigerant after the change of state has occurred.
b)
Superheat is the latent heat added to the vapor refrigerant after the change of state has occurred.
c)
Superheat is the sensible heat added to the liquid refrigerant after the change of state has occurred.
d)
Superheat is the sensible heat subtracted to the vapor refrigerant after the change of state has occurred.
27.
What is a starved coil?
a)
When a metering device is not feeding enough refrigerant to the coil, the coil is said to be a starved coil..
b)
When a compressor is not feeding enough refrigerant to the coil, the coil is said to be a starved coil..
c)
When a metering device is feeding refrigerant to the coil, the coil is said to be a starved coil..
d)
When a metering device is feeding too much refrigerant to the coil, the coil is said to be a starved coil..
28.
What is a typical problem on the liquid side of a liquid cooling evaporator?
a)
Mineral deposits that may build up on the liquid side and cause a poor heat exchange.
b)
Metal deposits that may build up on the liquid side and cause a poor heat exchange.
c)
Mineral deposits that may build up on the liquid side and cause a good heat exchange.
d)
Metal deposits that may build up on the liquid side and cause a good heat exchange.
29.
Why are the fins of a low temperature evaporator spaced wider apart than those on a high temperature evaporator?
a)
This allows for the formation of frost without blocking air flow.
b)
This allows for the formation of frost blocking air flow.
c)
This doesn't allow for the formation of frost without blocking air flow.
d)
This allows for the formation of heat without blocking air flow.
30.
What is a bearing washout?
a)
Bearing washout is when the lower oil level in the crankcase causes scoring of the bearing surfaces in the compressor.
b)
Bearing washout is when the higher oil level in the crankcase causes scoring of the bearing surfaces in the compressor.
c)
Bearing washout is when the lower oil level in the crankcase causes scoring of the bearing surfaces in the condenser.
d)
Bearing washout is when the higher oil level in the crankcase causes scoring of the bearing surfaces in the condenser.
31.
The refrigerant in a condenser in a refrigeration system ____.
a)
rejects heat
b)
absorbs heat
c)
changes to a vapor
d)
is under lower pressure than the evaporator
32.
A normally operating water-cooled condenser is operating with a 10°F 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)
Both are correct
b)
None are correct
c)
The outlet water temperature will be lower than expected.
d)
The system head pressure will rise.
33.
Mineral deposits on the water side of a water-cooled condenser act as a(n) ____.
a)
insulator
b)
conductor of heat
c)
cleaning solution
d)
They have no effect on the operation of the condenser.
34.
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)
greater than
b)
less than
c)
the same as
d)
slightly lower than
35.
The water circuit in shell-and-coil and tube-within-a-tube coil condensers must be cleaned ____.
a)
chemically
b)
by removing the end caps
c)
with a brush
d)
by air pressure
36.
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
37.
In a water-cooled condenser, a regulating valve is used to control the ____.
a)
refrigerant head pressure
b)
refrigerant flow through the pressure reducing device
c)
suction pressure
d)
water temperature
38.
Which of the following can be used to maintain the head pressure of a system with an air-cooled condenser?
a)
All of the above.
b)
Fan cycling.
c)
Dampers
d)
Condenser flooding.
39.
A water regulating valve helps to maintain a system's head pressure by modulating the flow of refrigerant through the condenser.
a)
False
b)
True
40.
The desired water flow through a condenser connected to a recirculating water system is approximately 3 gallons per minute per ton of refrigeration.
a)
True
b)
False
41.
When the evaporative condenser is used in cold climates, freeze protection must be provided in winter.
a)
True
b)
False
42.
If the spring pressure of a water regulating valve is increased, the system head pressure will also increase.
a)
True
b)
False
43.
High head pressures from low ambient can cause insufficient refrigerant flow rates through metering devices, which in turn can starve evaporators.
a)
False
b)
True
44.
Low suction pressures, iced coils, short cycling, and inefficient cooling, can also result from low head pressures.
a)
True
b)
False
45.
In a recirculating water system condenser, the leaving water temperature is normally ____________________°F lower than the condensing temperature of the refrigerant.
a)
10
b)
12
c)
8
d)
9
46.
An evaporative condenser uses air and ____________________ to desuperheat, condense, and subcool the refrigerant.
a)
Water
b)
Oil
c)
Nitrogen
d)
None of the above
47.
If an air-cooled condenser's fan motor stops running, the head pressure will ___________________.
a)
Increase
b)
Decrease
c)
Stay the same
d)
None of the above
48.
In order for a flooded condenser type head pressure control system to operate, a device called a(n) ____________________ holds the extra refrigerant in warmer weather when the condenser doesn’t need to be flooded.
a)
Receiver
b)
Accumulator
c)
Evaporator
d)
Compressor
49.
What is meant by the term blowdown?
a)
Water allowed to escape down the drain to keep minerals from overconcentrating.
b)
Refrigerant allowed to escape down the drain to keep minerals from overconcentrating.
c)
Oil allowed to escape down the drain to keep minerals from overconcentrating.
d)
Water allowed to escape down the drain to help minerals concentrate in the coils.
50.
What is the condenser saturation temperature if there is 20°F of subcooling and the outlet temperature of the refrigerant is 90°F?
a)
110°F
b)
70°F
c)
180°F
d)
45.5°F
51.
Define "subcooling."
a)
Subcooling is the reduction of the temperature of a liquid below its condensing temperature.
b)
Subcooling is the increase of the temperature of a liquid below its condensing temperature.
c)
Subcooling is the reduction of the temperature of a vapor below its condensing temperature.
d)
Subcooling is the increase of the temperature of a vapor below its condensing temperature.
52.
What would the symptom be if an air-cooled condenser had two fans and one stopped running?
a)
The symptom would be an increased head pressure.
b)
The symptom would be a decreased head pressure.
c)
The symptom would be no head pressure.
d)
The symptom would be no change in head pressure.
53.
Define "heat reclaim."
a)
The process of recovering heat from the system as when reusing the heat from the air-cooled equipment discharge gas for heating water, heating air, etc.
b)
The process of recovering cool from the system as when reusing the heat from the air-cooled equipment discharge gas for heating water, heating air, etc.
c)
The process of recovering heat from the system as when reusing the cool from the air-cooled equipment discharge gas for heating water, heating air, etc.
d)
The process of recovering cool from the system as when reusing the cool from the air-cooled equipment discharge gas for heating water, heating air, etc.
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