Refrigeration

Question 1

Explain pressure volume energy relationship

Answer 1

As pressure increases, volume decreases, and more energy is needed to boil a liquid

Question 2

Heat travels from…

Answer 2

Hot to cold

Question 3

3 methods of heat transfer

Answer 3

1. Conduction - Solid
2. Convection - Liquid
3. Radiation - Air

Question 4

Sensible Heat

Answer 4

Changes temp, NOT State

Question 5

Latent Heat

Answer 5

Changes state, NOT Temp

Question 6

Superheat

Answer 6

Every degree above its boiling point
e.g. 101 = 1 superheat

Question 7

Sub cooling

Answer 7

Cools and condenses into liquid and drops below boiling point

Question 8

Temperature energy graph

Answer 8

Temperature energy graph

Question 9

Basic refrigeration system

Answer 9

Basic refrigeration system

Question 10

Compressor

Answer 10

Pumps refrigerant around system

Question 11

Condenser

Answer 11

Cools refrigerant, changing state from gas to liquid

Question 12

Thermal Expansion Valve

Answer 12

Controls flowrate
Inc/Dec temp depending on temp of refrigerant leaving the evaporator

Question 13

Evaporator

Answer 13

Changes state of refrigerant from liquid to gas

Question 14

Condition of refrigerant as it flows from compressor to condenser

Answer 14

Hot, High Press Gas

Question 15

Condition of refrigerant as it flows from condenser to TEV

Answer 15

Warm, High Press liquid (Sub Cooled)

Question 16

Condition of refrigerant as it flows from TEV to evaporator

Answer 16

Very cold, low press liquid

Question 17

Condition of refrigerant as it flows fromevaporator to compressor

Answer 17

Cool, low press gas (superheated)

Question 18

LP Cut Out

Answer 18

Stops compressor if pressure drops too low

Question 19

HP cut out

Answer 19

stops the compressor if the pressure gets too high

Question 20

Oil Separator

Answer 20

Separates oil from the refrigerant

Question 21

Liquid Receiver

Answer 21

Store refrigerant during maintenance

Question 22

Drier

Answer 22

removes moisture from refrigerant

Question 23

Sight Glass

Answer 23

indicates moisture in the refrigerant

Yellow – there is moisture
Green – there isn’t moisture

Question 24

Refrigeration Procedures

Answer 24

1. Defrosting
2. Leak Detection
3. Lubrication

Question 25

When is defrosting required?

Answer 25

Ice builds up on evaporator coils

Question 26

Methods of defrosting

Answer 26

Natural Defrost Hot Gas Defrosting Electrical Heating coils

Question 27

How often is natural Defrost carried out?

Answer 27

Every 3-6 months

Question 28

How often is hot gas defrosting carried out?

Answer 28

Max of 1hr per 24hrs

Question 29

How often is electrical heating coils carried out?

Answer 29

Max of 1hr every 24hrs

Question 30

Why is Leak Detection used?

Answer 30

Refrigerant leaks are harmful to the environment and reduce refrigerant plant efficiency

Question 31

Methods of Leak Detection

Answer 31

1. Oil Slicks 2. IRLDS 3. Spectrolyne dye 4. Snoop 5. Halogen Leak Detector

Question 32

What is an oil Slicks?

Answer 32

where oil is leaking there will also be refrigerant leaking

Question 33

IRLDS

Answer 33

Infra-red leak detection system

Question 34

What kind of lubricants are needed for compressors?

Answer 34

Hygroscopic lubricants

Question 35

What do hygroscopic lubricants do?

Answer 35

Absorb moisture from the atmosphere

Question 36

What kinds of oils are used in refrigeration?

Answer 36

SUNISO 3GS SW68 OM70

Question 37

What source should oils be used

Answer 37

New, unopened cans

Question 38

Methods of How is oil added to compressors

Answer 38

1. Sump Filler Plug 2. Hand Punp 3. Dosing pot

Question 39

What is the Montreal protocol?

Answer 39

Agreement to phase out harmful ozone depleting substances

Question 40

Montreal Protocol substances

Answer 40

CFC HCFC Halons

Question 41

What is the Kyoto summit

Answer 41

Agreement to reduce all Greenhouse gases

Question 42

Greenhouse gas substances

Answer 42

Co2, HFC, PFC

Question 43

How is phosphine gas produced?

Answer 43

Refrigerants are heavier than air and will displace Oxygen If exposed to high temperatures they can produce PHOSGENE GAS

Question 44

Hazards of refrigerants

Answer 44

Can produce Cold Burns on exposed skin (Frost Bite) Decomposing Fruit and Veg can produce CO²

Question 45

What so you do if refrigerant gets in your eyes

Answer 45

flushing with running water and then require medical treatment.

Question 46

Procedure for entering refrigeration compartments

Answer 46

- Rating in charge of watch to be kept informed - Breathing Apparatus avaliable - High/Low exhaust fans running - No Smoking - IRLDS working correctl

Question 46

Procedure for entering refrigeration compartments

Answer 46

- Rating in charge of watch to be kept informed - Breathing Apparatus avaliable - High/Low exhaust fans running - No Smoking - IRLDS working correctly - personnel trapped warning lights working - sentry - internal door mechanism working

Question 47

What should happen to oil after use?

Answer 47

It should be disposed of in accordance with MARPOL

Question 48

Chilled water provides cooling for...

Answer 48

Weapons Systems Radars Ships Computer Systems Air Treatment Units (ATUs

Question 49

Main difference between chilled water, and refrigeration

Answer 49

The chilled water plant has a CHILLER in place of the EVAPORATOR

Question 50

What provides cooling for condenser and motors

Answer 50

sea water pump