Deck 8: Cooling Systems

Question 1

When a refrigerant leaves the condenser, what physical state is it in?

A) a cold, low-pressure liquid
B) a warm, high-pressure liquid
C) a hot, high-pressure gas
D) a hot, low-pressure gas

Answer 1

a warm, high-pressure liquid

Question 2

What ultimate purpose does the evaporator serve?

A) It mixes cool refrigerant with a room's air.
B) It evaporates the refrigerant from a liquid into a gas.
C) It removes heat from the room's air.
D) It expels heat from the refrigerant into the outdoor air.

Answer 2

It removes heat from the room's air.

Question 3

What ultimate purpose does the condenser serve?

A) removes heat from the room so that it can reduce the room's air temperature
B) It adds heat to the refrigerant so that it can cool off in the expansion valve.
C) removes heat from the refrigerant so that it can change state from a gas to a liquid
D) It heats water so that it can evaporate in the cooling tower.

Answer 3

removes heat from the refrigerant so that it can change state from a gas to a liquid

Question 4

When the refrigerant leaves the compressor, what physical state is it in?

A) a hot, high-pressure gas
B) a cold, low-pressure liquid
C) a hot, low-pressure gas
D) a warm, high-pressure liquid

Question 5

Dehumidification is achieved by:

A) completely closing the fresh-air intake to the system.
B) passing humid air over a pipe containing cold water or refrigerant, which causes the water to condense on the pipe an drip into a drain pan.
C) not operating an HVAC system on days when the relative humidity is high.
D) passing humid air through a filter that removes the water.

Question 6

According to Boyle's Law, pressure and volume have a(n):

A) positive relationship.
B) perverse relationship.
C) transverse relationship.
D) inverse relationship.

Question 7

Chilled water in a central air conditioning system is used to:

A) make ice cubes in an ice machine.
B) remove heat from the warm, humid air that is in the room.
C) cool people in a room by spraying a light, cooling mist over them.
D) mix with the refrigerant to remove heat from the refrigerant.

Question 8

Condenser water cools in the cooling tower through:

A) convection heat transfer.
B) evaporative heat transfer.
C) radiant heat transfer.
D) None of the above

Question 9

Which of the following is not an advantage of a PTAC unit?

A) quiet operation
B) low installation costs
C) low material costs
D) easy to maintain

Question 10

We need to repair leaks in the refrigeration system because:

A) losing refrigerant will reduce the efficiency of the heat transfer, costing us electricity and money.
B) losing refrigerant will force the system to work harder, resulting in early compressor failure.
C) the refrigerant chemical is dangerous for human exposure.
D) All of the above

Question 11

Refrigeration condenser and evaporator coils should be kept clean because:

A) accumulated dirt and dust will reduce the property's resale value.
B) accumulated dirt and dust attract mice.
C) accumulated dirt and dust are unattractive.
D) accumulated dirt and dust form a layer of insulation.

Question 12

Ceiling fans can reduce the perceived temperature of a space by:

A) 10 - 15° F.
B) 15 - 20° F.
C) 5 - 10° F.
D) Ceiling fans do not reduce the dry-bulb temperature.

Question 13

A chiller is used to:

A) cool water in the evaporator.
B) cool water in the cooling tower.
C) cool air in the evaporator.
D) cool water in the condenser.

Question 14

Which of the following is not an example of an internal cooling load?

A) ovens
B) mixing (outside) air
C) lighting
D) computers

Question 15

From a physics perspective, there is no such thing as cold -- there is only an absence of heat.