Condenser, Evaporator, Metering Device Pretest

Question 1

Closing the condenser housing louvers can be used to raise low head pressure in low ambient temperatures

True or False

Answer 1

True

Question 2

Some water defrost systems spray a lithium chloride brine solution solution over the evaporator

True or False

Answer 2

True

Question 3

Some commercial refrigeration applications require that water be kept from freezing at temperatures below 32F

True or False

Answer 3

True

Question 4

A fixed orifice metering device consists of a length of seamless tubing with a small and precisely formed inside diameter

true or false

Answer 4

false

Question 5

systems equipped with a high-side float use a separate liquid receiver

true or false

Answer 5

false

Question 6

A PWM solenoid EEV can hold its value at any variable position between open and closed for the purpose of modulating refrigerant

True or False

Answer 6

False

Question 7

Hunting might allow liquid refrigerant to reach the compressor and cause compressor damage

True or False

Answer 7

True

Question 8

In a system that uses a standard TXV, high-side and low-side pressures balance during the off cycle.

True or False

Answer 8

False

Question 9

A TXV can adjust the refrigerant flow rate to compensate for varying loads

True or False

Answer 9

True

Question 10

A filter-drier should be placed in the liquid line ahead of the TXV

True or False

Answer 10

True

Question 11

Capillary tubes regularly function as check valves

True or False

Answer 11

False

Question 12

A suction line-liquid line heat exchanger ______

a) superheats liquid refrigerant on the high side
b) superheated vapour refrigerant in the suction line
c) promotes a steady column of liquid in the suction line
d) all of the above

Answer 12

b)

Question 13

A hot water reclaim tank is a cylinder filled with water that absorbs heat from refrigerant flowing through a refrigeration systems ________

a) discharge line
b) suction line
c) accumulator
d) sight glass

Answer 13

a) discharge line

Question 14

Counterflow in a tube-within-a-tube condenser allows

a) the warmest water to be adjacent to the warmest refrigerant
b) the coolest refrigerant to be next to the coolest water
c) a steady transfer of heat throughout the entire condenser
d) all of the above

Answer 14

d) all of the above

Question 15

A condenser in which a water tubing winds around the inside of a metal refrigerant shell is called a __________

a) air cooled
b) shell and coil
c) shell and tube
d) tube within a tube

Answer 15

b) shell and coil

Question 16

Some types of water-cooled condensers use ________________

a) the top part of the shell as liquid receiver
b) bottom part of shell as liquid receiver
c) both and B
d) neither A or B

Answer 16

b) bottom part of shell

Question 17

A condenser that uses only water as the medium into which system heat is expelled is a ________________

a) air cooled
b) water cooled
c) evaporative
d) all of the above

Answer 17

d) all of the above

Question 18

In a hot-gas defrost system, the evaporator is defrosted by:

a) refrigerant from the vapour line
b) suction vapour from the low side
c) warm liquid refrigerant from the high side
d) hot exhaust fumes from a gas or diesel engine

Answer 18

a) refrigerant vapour from the discharge side

Question 19

In what type of defrost system is hot refrigerant gas diverted to the evaporator to expedite the defrosting process?

a) off cycle defrost system
b) pump down defrost system
c) electric defrost system
d) none of the above

Answer 19

d) none of the above

Question 20

Which of the following statements regarding off cycle defrost systems is FALSE?

a) frost accumulates during the on cycle
b) evaporator fans continue to circulate air during off cycle
c) the heat in the air circulated during the off cycle melts the frost
d) it can only be used in very low temperature systems

Answer 20

d) it can only be used in very low temperature systems

Question 21

An electric heat defrost system ________

a) energizes electric heating coils
b) applies an electric voltage directly to the frost covered coil
c) used illuminated heat lamps
d) none of the above

Answer 21

a) energizes electric heating coils

Question 22

Which of the following statements regarding water defrost systems is false?

a) water delivery may be dropped through a pan located over the evaporator
b) water delivery may be through a spray
c) water delivery may be done during a cooling cycle with the compressor running
d) the water running over the evap is warm enough to melt the ice

Answer 22

c) water delivery may be done during a cooling cycle with the compressor running

Question 23

A condensate pump is used to __________

a) remove the moisture that builds up from defrosting and compensating
b) move water to a cooling towers gravity flow basin
c) provide water pressure for an evaporative cond

Answer 23

a)

Question 24

A defrost timer that turns on defrost operations at a preset time and stops defrosting operations when the evaporator reaches a preset cut-out temperature is a _______________ defrost timer

a) time-initiated, temperature-terminated
b) time-initiated, pressure-terminated
c) time initiated, time-terminated

Answer 24

a)time initiated , temperature terminated

Question 25

Surfaces in and along air ducts that direct air flow through the evaporator and throughout the cabinet are called; a) off center plates b) fittings c) wet plates d) baffles

Answer 25

d) baffles

Question 26

Heat exchangers made from two metal sheets that are welded together to form a series of passages are ___________ evaporators a) baffle-tube b) fin-and-tube c) plate d) shell-and-sheet

Answer 26

c) plate

Question 27

A liquid-cooling evaporator ____________ a) uses a cooled liquid that acts as the primary heat transfer medium b) can be immersed or tube-within-a-tube c) is designed to cool a liquid rather than air d) all of the above

Answer 27

d) all of the above

Question 28

An evaporator that depends on gravity for air circulation is a ___________ evaporator a) forced-draft b) natural-draft c) quick-draft d) all of the above

Answer 28

b) natural-draft

Question 29

The function of EEV’s is to maintain _________ at a desired setting a) superheat b) sub cooling c) ambient temperature d) head pressure

Answer 29

a) superheat

Question 30

On a cap tube system, severe frosting is the suction line during compressor start-up indicates a __________ a) overcharge b) undercharge c) refrigerant leak d) none of the above

Answer 30

a) overcharge

Question 31

Electronic expansion valves (EEV’s) use a _______ -operated assembly a) spring b) diaphragm c) bellows d) none of the above

Answer 31

d) none of the above

Question 32

To maintain a constant pressure in the evaporator when the system is running, an AXV _______ refrigerant flow when the evaporator pressure drops a) decreases b) stabilizes c) increases d) none of the above

Answer 32

c) increases

Question 33

Pulse width-modulating (PWM) solenoid EEV’s are refrigerant metering devices that use a pulse width modulation signal to control the operation of a _______ for variable refrigerant flow a) stepper motor b) diaphragm c) solenoid valve d) bleed valve

Answer 33

c) solenoid valve

Question 34

Low-side float (LSF) metering devices control the flow of liquid refrigerant into the _________ a) sensing bulb b) compressor c) evaporator d) suction line

Answer 34

c) evaporator

Question 35

Increasing the ______ too much will starve the evaporator a) superheat b) sub cooling c) undercooking d) none of the above

Answer 35

a) superheat

Question 36

The orifice size of a metering orifice may need to be changed for units with long _______ sets to account for the extra refrigerant charge a) filter drier b) suction line c) piston d) expansion

Answer 36

b) suction line

Question 37

When a capillary tube serves the function of both the liquid line and the metering device, it is connected between the evaporator and the ___________ a) suction line b) condenser c) compressor d) accumulator

Answer 37

b) condenser

Question 38

The ________ of the cap tube determines how much pressure drops between the condenser and evaporator a) length b) inside diameter c) number of turns d) all of the above

Answer 38

d) all of the above

Question 39

Metering devices that can change their orifice size to account for changes in cooling loads are referred to as ________ metering devices a) modulating b) flow c) fixed d) limited

Answer 39

a) modulating

Question 40

The primary purpose of a metering device is to produce ________ a) pressure drop b) temperature drop c) sub-cooling d) superheat

Answer 40

a) a pressure drop