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WorksheetsUnit 3 Quiz
Total questions: 97
Worksheet time: 49mins
What term is used to describe the measurement of refrigeration capacity?
Degree of refrigeration
Ton of refrigeration
Pound of refrigeration
Refrigeration quotient
Which of the following is NOT a purpose of the compressor in a refrigeration cycle?
To increase the refrigerant pressure
To circulate the refrigerant
To cool the refrigerant
To decrease the volume of the refrigerant
What is the relationship between pressure and the boiling point of water or other liquids?
Pressure and boiling point are inversely proportional
Pressure and boiling point are directly proportional
Pressure has no effect on the boiling point
Boiling point decreases as pressure increases
Which color is NOT typically designated for a refrigerant cylinder?
Blue
Green
Yellow
Red
What should be plotted on a pressure/enthalpy diagram for a refrigerant blend (R-407C) that has a noticeable temperature glide?
A refrigeration cycle with constant temperature lines
A refrigeration cycle with constant pressure lines
A refrigeration cycle with constant enthalpy lines
A refrigeration cycle with a noticeable temperature glide
What should be properly ventilated to prevent hazards associated with refrigerant leaks?
Storage areas for tools
Areas with potential for refrigerant leaks
Office spaces
Dining areas
When should extra precautions be taken to prevent refrigerant leaks?
When working near an open flame
During regular office hours
When the system is turned off
While refilling office supplies
What protective gear should be worn when handling refrigerants?
Heat-resistant suit
Goggles with side shields and gloves
Earplugs
Steel-toed boots
Refrigerants should be transferred from the container to a system or from the system to what type of container?
A recycled container
An unapproved container
A new container
An approved container
What is the term refrigeration used to describe in this context?
The process of heating food
The process of preserving food and comfort cooling
The process of freezing water into ice
The process of cooking food at low temperatures
What is considered the frozen hard point for most foods?
35°F
45°F
32°F
0°F
Which temperature range is known as medium temperature in the refrigeration industry?
35°F to 45°F
0°F to 32°F
45°F to 55°F
Below 0°F
What were the first ice boxes made of?
Metal
Wood
Plastic
Cork
What would constitute a refrigerator according to the text?
A box insulated with cork
A cooling unit placed where the ice was located
A box made of metal
A box placed in the coldest room in the house
Who could afford ice manufactured by mechanical refrigeration in the early 1900s?
Everyone in the society
Only the wealthy
Only the middle class
Only the working class
What new feature did some models of modern refrigerators include?
Manual ice dispensers
Connections to the World Wide Web
Built-in radio systems
Manual temperature control
Why did centralized frozen food lockers become established before World War II?
Because frozen food was cheaper
Because most people had a freezer at home
To allow a family to have its own locker for frozen food
Because refrigerated food was not popular
Why is food that is frozen fresh appealing?
It is less expensive than other foods
It stays fresh for a longer period of time
It can be cooked directly without thawing
It has more nutrients than refrigerated food
What is a common perception about refrigerated and frozen foods in modern times?
They are considered luxury items
They are taken for granted
They are seen as less healthy
They are only for special occasions
What is the process of refrigeration primarily concerned with?
Adding heat to a place where it is wanted
Removing heat from a place where it is not wanted and transferring it to a place where it makes little or no difference
Maintaining the same temperature inside and outside the refrigerator
Increasing the temperature inside the refrigerator to match room temperature
What is the typical temperature range for a household room from summer to winter?
Between 35°F and 90°F
Between 70°F and 90°F
Between 0°F and 35°F
Between 50°F and 70°F
Why is it recommended to allow food to cool down to room temperature before placing it in the refrigerator?
To prevent the food from spoiling
To increase the efficiency of the refrigerator
To warm up the refrigerator interior
To reduce the risk of freezing the food
What is the phenomenon called when cooler air falls out of the refrigerator and is replaced with warmer air at the top?
Heat exchange
Thermal inversion
Heat leakage
Air displacement
How does heat transfer into the refrigerator according to the text?
By convection
By conduction
By radiation
It does not transfer heat
What is considered as heat leakage in a refrigerator?
Cold air escaping from the refrigerator
Warm food placed in the refrigerator
The refrigerator running out of power
Ice forming on the freezer walls
What must be done if heat is added to the refrigerator?
The added heat must be contained
The added heat must be removed
The refrigerator should be turned off
The temperature inside the refrigerator should be increased
What will happen if the added heat is not removed from the refrigerator?
The temperature inside the refrigerator will drop
The refrigerator will use less energy
The temperature inside the refrigerator will rise
The food inside the refrigerator will freeze faster
What is the primary function of the components of a refrigerator according to the text?
To cool the food directly
To pump the heat up the temperature scale from the refrigeration compartments to the room
To freeze the food inside the refrigerator
To circulate air within the refrigerator
What would happen if the refrigerator raised the air temperature inside enough to affect the food?
The food would cook
The food would become dehydrated
The food would spoil
The food would ferment
At what temperature does the text suggest a refrigerator's interior is typically maintained?
70°F
0°F
35°F
100°F
What analogy is used in the text to describe the process of pumping heat out of the refrigerator?
Pushing a boulder up a hill
Pumping water from a valley to the top of a hill
Driving a car uphill
Boiling water on a stove
What type of energy does an electric motor use to pump heat out of the refrigerator?
Gasoline
Solar
Electric
Thermal
What is required to move heat from a lower temperature area to a higher temperature area according to the text?
Natural convection
Energy that must be purchased
Manual labor
Solar power
What is the comparison made to illustrate the concept of pumping heat up the temperature scale?
Pushing a car uphill
Pumping water uphill
Climbing a mountain
Heating water on a stove
What type of refrigeration is residential air-conditioning considered to be?
Low-temperature refrigeration
Medium-temperature refrigeration
High-temperature refrigeration
No-temperature refrigeration
What does the air conditioner do with the heat from inside the house?
It cools the heat and recirculates it inside the house.
It dissipates the heat into the ground.
It pumps the heat from inside the house to the outside.
It converts the heat into electrical energy.
What happens to the air that goes into the air-conditioning unit at approximately 75°F?
It is expelled outside as hot air.
It is used to heat the house.
It comes out at approximately 55°F.
It remains at the same temperature.
What is the outside design temperature mentioned in the document?
40°F
75°F
95°F
125°F
What is the temperature of the air after it passes over the cooling coil and before it enters the fan, as per the document?
40°F
55°F
75°F
95°F
According to the document, what is the function of the outside coil in the air-conditioning system?
It pumps heat into the house.
It cools the air inside the house to 40°F.
It transfers heat from the system to the outside air.
It increases the temperature of the air entering the unit.
Based on the information provided, what must the air-conditioning system capacity be large enough to do?
Increase the heat inside the house.
Maintain a constant temperature of 55°F inside the house.
Pump the heat out of the house faster than it is leaking back in.
Cool the outside air to 125°F before it enters the house.
What is the boiling point of water at sea level when the barometric pressure is at the standard value of 29.92 in. Hg?
203.4°F
250°F
212°F
100°C
According to the text, how can the boiling point of water be changed and controlled?
By controlling the temperature of the water
By controlling the vapor pressure above the water
By changing the water's chemical composition
By altering the water's physical state
What happens to the pressure if the temperature in a closed container is increased?
The pressure decreases
The pressure remains constant
The pressure increases
The pressure fluctuates unpredictably
Why is understanding the temperature/pressure relationship important in refrigeration?
It helps in predicting weather patterns
It is crucial for the maintenance of the refrigeration system
It allows control over the temperatures that the system will maintain
It is only important for cooking food at high altitudes
At what temperature does water boil in Denver, Colorado, which is about 5000 ft above sea level?
212°F
250°F
203.4°F
100°C
What is the absolute pressure in inches of mercury (in. Hg) at a water temperature of 30°C?
0.081
0.165
0.050
0.103
At what water temperature does the absolute pressure reach 0.507 inches of mercury (in. Hg)?
60°C
70°C
80°C
50°C
What is the absolute pressure in inches of mercury (in. Hg) when the water temperature is 42°C?
0.268
0.131
0.122
0.289
If the water temperature is 50°C, what is the absolute pressure in inches of mercury (in. Hg)?
0.178
0.362
0.256
0.739
At what temperature does water boil when the atmospheric pressure is 29.92 in. Hg according to the chart?
100°F
212°F
180°F
160°F
What is the absolute pressure in lb/in² (psia) when the water temperature is 160°F?
3.719
4.742
5.994
7.512
According to the chart, what is the absolute pressure in inches of mercury (in. Hg) at a water temperature of 150°F?
5.881
7.573
9.656
12.203
At what temperature does water boil when the atmospheric pressure is 24.92 in. Hg?
212°F
203°F
250°F
100°C
Why does water boil at a temperature higher than 212°F in a pressure cooker?
Because the atmospheric pressure is lower than normal
Because the vapor pressure is lower than atmospheric pressure
Because the pressure in the vessel is above atmospheric pressure
Because the heat is removed from the water
What is the boiling point of water at sea level with an atmospheric pressure of 29.92 in. Hg or 14.696 psia?
203°F
250°F
212°F
100°C
What is the vapor pressure inside a pressure cooker when the water boils at 250°F?
24.92 in. Hg
29.92 in. Hg
15 psig
14.696 psia
What happens to the boiling point of water when the pressure is increased, according to the water temperature/pressure table?
It decreases
It remains the same
It increases
It fluctuates unpredictably
At what pressure will water start to boil at 70°F according to the experiment described?
1 atm
0.739 in. Hg (0.363 psia)
15 psig
250°F
What is the purpose of boiling water at a temperature low enough to absorb heat out of a room as mentioned in the text?
To increase the pressure
To create steam for industrial use
To have comfort cooling (air-conditioning)
To measure the atmospheric pressure
What does Figure 3.13 illustrate?
The relationship between water temperature and pressure
The setup for measuring atmospheric pressure
The boiling point of water at different pressures
The setup of an experiment demonstrating the boiling point of water at 70°F and a pressure of 0.739 in. Hg
What happens to the water in the bell jar when the pressure is lowered to correspond to a temperature of 40°F?
The water remains at the same temperature but stops boiling.
The water boils at 40°F due to the reduced pressure.
The water freezes because of the temperature drop.
The water temperature increases due to the pressure change.
What is the pressure of water boiling at 40°F in the example provided?
0.122 psia
0.248 in. Hg
75°F
0.248 psia
Why is the air leaving the cooling coil cold when water at 40°F is circulated through it?
Because the water absorbs heat from the air.
Because the air gives up heat to the coil.
Because the coil is naturally cold.
Because the air is compressed by the coil.
What is a refrigerant according to the text?
A substance that changes from a solid to a liquid at practical pressures.
A substance that changes from a liquid to a gas at impractical pressures.
A substance that can be changed readily to a vapor by boiling it and then changed to a liquid by condensing it.
A substance that cannot change its characteristics repeatedly.
Why is water not normally used as a refrigerant in most applications?
Because it cannot change from a liquid to a vapor and back at practical pressures.
Because it is not familiar to most people.
Because it changes its characteristics too often.
Because it is only used for small applications for reasons that will be discussed later.
What does a vapor pressure of 68.5 psig for R-22 indicate about its temperature?
It indicates that the temperature is below 40°F.
It indicates that the temperature is exactly 40°F.
It indicates that the temperature is above 40°F.
It indicates that the temperature is unrelated to the pressure.
Under which two conditions will the pressure and temperature of a refrigerant correspond when both liquid and vapor are present?
When the refrigerant is non-condensable and when it is at equilibrium.
When the refrigerant is at equilibrium and when it is non-saturated.
When the change of state is occurring and when the refrigerant is at equilibrium.
When the refrigerant is superheated and when it is subcooled.
What is the term used to describe a refrigerant when both liquid and vapor can exist simultaneously?
Subcooled
Superheated
Saturated
Equilibrated
What does the saturation temperature of a liquid/vapor mixture depend on?
The size of the container
The type of refrigerant only
The pressure of the liquid/vapor mixture
The ambient temperature only
What happens to the pressure inside a cylinder of R-22 when it is moved from a walk-in cooler at 35°F to a warmer room at 75°F?
The pressure decreases because the liquid inside starts to freeze
The pressure remains the same as no outside forces are acting on it
The pressure increases because the liquid inside starts to boil slightly and creates vapor
The pressure increases because the vapor inside condenses
At what pressure does the cylinder of R-22 stabilize when it reaches room temperature of 75°F?
61.5 psig
132 psig
196 psig
75 psig
What is indicated by a temperature/pressure chart for a refrigerant like R-22?
The efficiency of the refrigerant at different temperatures
The saturation temperatures for different saturation pressures
The amount of refrigerant needed for different room temperatures
The boiling point of the refrigerant at atmospheric pressure
When the cylinder of R-22 and its contents are at room temperature and in equilibrium, what is the state of the refrigerant?
It is unsaturated at 75°F
It is superheated at 75°F
It is saturated at 75°F
It is subcooled at 75°F
What happens to the vapor in the cylinder of R-22 when it is moved into a 35°F walk-in cooler?
The vapor increases in pressure.
The vapor condenses into a liquid.
The vapor remains unchanged.
The vapor turns into a gas.
At what temperature are the liquid and vapor refrigerant in the cylinder of R-22 saturated when placed in a 35°F cooler?
75°F
35°F
61.5 psig
132 psig
What is the cylinder pressure of R-22 when the partial liquid, partial vapor mixture reaches the cooler temperature of 35°F?
132 psig
75°F
61.5 psig
It is not specified
What is vapor pressure?
The pressure exerted by the atmosphere on a liquid
The pressure exerted on top of a saturated liquid
The pressure inside a cylinder of R-22 at equilibrium
The pressure exerted by a gas in a closed container
What happens to vapor pressure when the temperature of the liquid/vapor mixture increases?
Vapor pressure decreases
Vapor pressure remains constant
Vapor pressure increases
Vapor pressure fluctuates unpredictably
At what temperature does R-22 boil when the pressure is lowered to atmospheric pressure?
100°F
196 psig
-41°F
0°F
What effect does the loss of vapor pressure have on the liquid remaining in the cylinder of R-22?
It causes the liquid to freeze
It causes the liquid to remain at a constant temperature
It causes the liquid to boil and drop in temperature
It causes the liquid to increase in temperature
Why is it against the law to intentionally release refrigerant into the atmosphere?
Because it can cause the refrigerant to boil
Because it can cause a drop in temperature
Because it is harmful to the environment
The text does not provide this information
What will happen if the liquid valve of a refrigerant (R-22) cylinder is opened very slowly and directed into a cup?
The liquid refrigerant will freeze.
The liquid refrigerant will flow from the cylinder and accumulate in the cup.
The liquid refrigerant will evaporate before reaching the cup.
The liquid refrigerant will turn into a gas immediately upon exiting the cylinder.
At what temperature will the liquid R-22 continue to boil until all the liquid has vaporized when trickling out into a cup at 0 psig?
32°F
0°F
-41°F
100°F
Why is it illegal to perform the experiment where refrigerants are released into the atmosphere?
Because it can cause an explosion.
Because it is a waste of refrigerant.
Because it can harm the ozone layer.
Because it is illegal to intentionally vent or release refrigerants into the atmosphere.
What is the purpose of the warning "Again, do not perform the preceding experiments."?
To prevent the misuse of refrigerant.
To ensure safety protocols are followed.
To comply with legal regulations.
All of the above.
What is the temperature at which the liquid will boil when a copper tubing is attached to the valve on the liquid line of an R-22 cylinder and liquid is allowed to trickle into the tubing at atmospheric pressure?
32°F
0°F
-41°F
100°F
Why is it illegal to perform the experiment described in the text?
Because it is a waste of refrigerant
Because it can cause injury to the experimenter
Because it is harmful to the ozone layer
Because intentionally venting refrigerant into the atmosphere is illegal
Which of the following is NOT one of the four major components that make up mechanical refrigeration systems?
The evaporator
The compressor
The condenser
The expansion valve
What can be eliminated by adding some components to a refrigeration system?
Electrical issues
Temperature/pressure problems
Noise levels
Energy consumption
What is the function of the evaporator in a refrigeration system?
To release heat into the system
To absorb heat from the system
To maintain the temperature of the refrigerant
To increase the temperature of the substance to be cooled
At what temperature is the evaporator operated to absorb heat from the air in the example provided?
75°F
40°F
100°F
32°F
Why is the boiling temperature of 40°F chosen for the evaporator in air-conditioning systems?
Because it is the freezing point of the coil
Because it is the ideal room temperature
Because it is well above the freezing point of the coil
Because it is the maximum temperature the coil can handle
What analogy is used to describe the function of the evaporator?
A "heat magnet"
A "heat exchanger"
A "heat sponge"
A "heat pump"
What percentage of the R-22 refrigerant enters the coil as liquid and vapor respectively?
50% liquid and 50% vapor
75% liquid and 25% vapor
25% liquid and 75% vapor
100% liquid
What is the direction of refrigerant flow through the coil in relation to the direction of the rising vapor?
The refrigerant flow is in the opposite direction to the rising vapor.
The refrigerant flow is in the same direction as the rising vapor.
The refrigerant flow is perpendicular to the rising vapor.
The refrigerant flow direction is not related to the rising vapor.
At what point in the evaporator coil does the refrigerant become approximately 90% vapor?
Just before the end of the coil.
At the beginning of the coil.
Halfway up the coil.
After the refrigerant leaves the coil.
