21

Question 1

A high evaporator superheat indicates

Answer 1

An undercharged system

Question 2

What type of heat removes moisture from the air in a refrigerator?

Answer 2

Latent heat

Question 3

Where is the thermocouple placed to measure system superheat?

Answer 3

Right before compressor

Question 4

The residential refrigerator fresh food compartment typically ranges from

Answer 4

35°F to 40°F

Question 5

High-temperature refrigeration applications will normally provide box temperatures of

Answer 5

47°F to 60°F

Question 6

What are the three functions of the evaporator?

Answer 6

Liquid to vapor, superheat, absorb heat.

Question 8

The household refrigerator fresh food compartment is a good example of_______ refrigeration.

Answer 8

medium-temperature

Question 9

Can be accomplished with heat from the system or using an electric heater.

Answer 9

Defrost

Question 10

Two pieces of metal stamped with the impression of a pipe passage through it.

Answer 10

Stamped evaporator

Question 11

Reduces pressure drop inside the evaporator.

Answer 11

Multiple circuit coil

Question 12

A refrigeration system operated with the liquid refrigerant level very close to the outlet of the evaporator coil for improved heat exchange.

Answer 12

Flooded evaporator

Question 13

Hight-temp, high-pressure vapor from discharge side of the compressor.

Answer 13

Hot gas

Question 14

When a metering device is not feeding enough refrigerant to the coit resulting in higher superheat and rise in box temperature.

Answer 14

Starved coil

Question 15

Copper or aluminum tube that has fins usually made of aluminum pressed onto the copper lines to extend the surface area of the tubes.

Answer 15

Finned tube evaporator

Question 16

Medium temp refrigeration where evaporator coil operates below freezing but the air in the cooler is above freezing. Coil is defrosted by the air inside the cooler while the compressor is off.

Answer 16

Off cycle defrost

Question 17

Component between the high-pressure liquid line and the evaporator that feeds the liquid refrigerant into the evaporator.

Answer 17

Expansion device (metering)

Question 18

Absorbs heat into the system from whatever medium is to be cooled.

Answer 18

Evaporator

Question 19

When the refrigerated space is allowed to warm up considerably, the system must go through this to compensate for the excessive heat load on the evaporator.

Answer 19

Hot pulldown

Question 20

Dry type evaporator where the refrigerant is boiled off before leaving the evaporator.

Answer 20

Direct expansion evaporator

Question 21

What are three methods used to defrost an evaporator?

Answer 21

Electric heater, hot gas, passive off cycle

Question 22

Low temperature coils have fin spacings that are narrower than medium
temperature coils. T/F

Answer 22

F

Question 23

Wet compression happens when liquid refrigerant gets past the piston oil rings and vaporizes upon compression, absorbing heat from the cylinder walls and reducing the discharge line temperature.

Answer 23

T

Question 24

Hot gas defrost uses vapor taken off the top of the receiver. T/F

Answer 24

F

Question 25

In a tube-in-tube evaporator coil, water is in the outer tube and refrigerant flows in the inner tube in the opposite direction of the water. T/F

Answer 25

T

Question 26

When moisture is removed from the air, latent heat is removed. T/F

Answer 26

T

Question 27

Aluminum parallel flow plates are oriented horizontally for use in condensers and vertically for evaporators. T/F

Answer 27

T

Question 28

One of the higher low-temperature applications is the making of ice. T/F

Answer 28

T

Question 29

Best time to take a superheat reading is when the system is in a hot pulldown. T/F

Answer 29

F

Question 30

The______ of the liquid refrigerant determines the coil operating temperature.

Answer 30

Boiling temp

Question 31

Heat that is added to the refrigerant is after it has all vaporized is called

Answer 31

Superheat

Question 32

If the evaporator temperature is below 32°F, there must be some provision for _

Answer 32

Defrost

Question 33

A saturated vapor condition exists when

Answer 33

all the liquid has boiled to a vapor

Question 34

Refrigeration designed for the purpose of storing flowers or candy is considered _

Answer 34

High temp

Question 35

A saturated vapor condition exists when

Answer 35

all the liquid has boiled to a vapor

Question 36

The latent heat absorbed by the evaporator while it is changing state is_____ then sensible heat added to the vapor leaving the coil.

Answer 36

More concentrated

Question 37

The best heat exchange occurs between what type of mediums?

Answer 37

Liquid

Question 38

What type of material may be used to manufacture evaporators? (List three)

Answer 38

Aluminum, copper, stainless

Question 39

What type of evaporator is used more than any other type of heat exchanger between air and refrigerant?

Answer 39

Finned tube

Question 40

A dirty evaporator coil will cause what type of symptoms?

Answer 40

Insulation on the coil, excessive superheat, not make temp

Question 41

When hot gas is used for defrost, what controls the flow of the hot gas into the evaporator?

Answer 41

Solenoid valve on discharge line after compressor.