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Refrigeration II > Modern refrigeration and air conditioning Ch. 17-20 > Flashcards

Modern refrigeration and air conditioning Ch. 17-20 Flashcards

1
Q

What happens to the high and low side pressures during the off cycle?

A

They become equal.

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2
Q

Fast freezing preserves food better than slow freezing because…

A

Slower oxidation and foods form smaller water crystals (less damaging).

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3
Q

Refrigerator should be set to maintain product temperature of _____ or less

A

40°F (4.5°C)

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4
Q

What is the main advantage of a chest freezer compared to an upright freezer?

A

Efficiency! less cold air lost when lid is opened (cold air falls)

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5
Q

The evaporator in most refrigerator-freezers is located…

A

In the freezer compartment top of cabinet

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6
Q

In a refrigerator-freezer, the percentage of cold air that is delivered to the fresh-food compartment is controlled by the ______

A

Damper

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7
Q

The outer shell of a refrigerator-freezer is typically made from….

A

Sheets of steel

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8
Q

When closed, the refrigerator door seals tightly to the cabinet because of ________

A

small magnets in the gasket

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9
Q

Wine cooler doors are typically made of _____

A

Double-paned, tempered, safety glass

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10
Q

Is it common for a domestic refrigerator-freezer to contain some liquid refrigerant in the evaporator?

A

Yes.

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11
Q

What is the common evaporator temperature range in a domestic refrigerator-freezer?

A

0°F to -25°F (-18°C to -32°C)

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12
Q

most common compressor used in domestic refrigerators?

A

Split Phase

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13
Q

on start up a motor may draw an overload of up to __%

A

600%

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14
Q

poor air circulation in a natural draft condenser =

A

high head pressure, incresed run-time, and insufficient cooling.

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15
Q

hot wall condenser uses

A

tubing that is in direct contact with the outer wall of the cabinet which serves as a heat sink

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16
Q

forced draft condenser does…

A

takes air in from the front of the refrigerator and expells the air out of the back

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17
Q

cardboard partitions do what?

A

direct air flow

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18
Q

most common metering device in domestic refrigerators

A

capillary tube

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19
Q

what is the purpose of the filter drier

A

to prevent moisture from entering the metering device where it could freeze and cause clogging

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20
Q

what does the evaporator do

A

absorbs heat in the cabinet when refrigerant passes through it

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21
Q

what is the purpose of the heat exchanger between the capillary tube and suction line

A

to prevent liquid refrigerant to the compressor and to provide sub cooling to liquid refrigerant before it enters the evaporator

22
Q

most common fixed temperature range in domestic refrigerators

A

37-41°f

23
Q

semi automatic defrost

A

button must be pressed to begin defrost cycle and it automatically cycles back to normal run

24
Q

automatic defrost

A

electric heating element next to evaporator with a timer operates during the off cycle

25
Q

demand defrost

A

active based on number of times refrigerator is opened

26
Q

continuous defrost

A

counts down to next defrost cycle no matter if compressor is running

27
Q

timed defrost

A

uses a timer to set a predetermined time to defrost

28
Q

mullion heater

A

electric heater installed arounf the door openings to prevent condensation from forming

29
Q

flow of wate in automatic ice makers are regualted by

A

solenoid water valve

30
Q

low water pressure can make ____ ice cubes

A

hollow

31
Q

3 steps to automatic ice maker

A

fill, freeze, harvest

32
Q

best method of cutting capillary tubing is…

A

making a notch with a file and bending the tubing back and forth

33
Q

2 methods for crushed ice

A

auger and reverse auger

34
Q

refrigerators should only be installed in rooms that are __ square ft or larger

A

100

35
Q

there should be serveral large loops in refrigerator water line to?

A

move the refrigerator with out disconnecting the water connection

36
Q

an extention cord may cause ?

A

an un exceptable voltage drop

37
Q

hot wall condenser refrigerator must have atleast __” of air space

A

2

38
Q

if a refrigerator does not start and the inside light does not come on what is most likely the problem

A

elecrical circuit

39
Q

a leaky door gasket can cause …

A

build up of frost on the evaporator

40
Q

what can prevent a newly installed ice maker from working properly

A

if the lice maker temp is held at 20 °f

41
Q

compressor condition, storage space, and temperature outside of the cabinet affects what

A

freezer cycling time

42
Q

over charge of refrigerant can result in

A

frost on the suctionline

43
Q

a system has symptoms of restriction in the metering device but begins acting normally when heat is applied what is the most likely cause

A

moisture in the system

44
Q

condenser and compressor should be cleaned atleast…

A

every three months

45
Q

a vacuum with a brush attachment can be used to …

A

clean the compressor and condensor

46
Q

in a compressor burn out ___ mixes with refrigerant and oil cause an odor

A

burnt electrical wiring

47
Q

a filter drier on the high side should be installed at the

A

capillary tube inlet

48
Q

a second filter drier on the low side will prevent what

A

repeat compressor burnout

49
Q

indication a system is low on refrigerant

A

high low side pressure

50
Q

oil should be replaced when?

A

in the event of a leak

51
Q

when discarding a refrigerator you must

A

remove the doors, reclaim the refigerant, and place a label indicating the refrigerant has been reclaimed

Refrigeration II (1 decks)

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