Refrigeration

Question 1

Complete the sentence

When Pressure increases, Volume ____ and ____ Energy is required to boil a liquid

Answer 1

Volume Decreases

More Energy

Question 2

Complete the sentence

When Pressure decreases, Volume ____ and ____ Energy is required to boil a liquid

Answer 2

Volume Increases

Less Energy

Question 3

How does heat travel?

Answer 3

Hot to Cold

Question 4

What ways can heat be transferred?

There are 3 ways

Answer 4

-Conduction
-Convection
-Radiation

Question 5

Define Conduction

Answer 5

Heat transfer through a solid

Question 6

Define Convection

Answer 6

Heat transfer through a fluid

Question 7

Define Radiation

Answer 7

Heat transfer through a space

Question 8

Define Sensible Heat

Answer 8

Heat required to change Temperature, not the State of a substance

Question 9

Define Latent Heat

Answer 9

The heat required for a Change of State in a substance, while the Temperature remains constant

Question 10

Define Superheat

Answer 10

When a substance goes above its Boiling Point it is Superheated; For every degree it goes above its boiling temperature, it gains one degree of Superheat

Question 11

Define Sub-Cooling

Answer 11

When a substance cools and condenses into a liquid and drops below the boiling point it is Sub-Cooled; For every degree it drops below boiling point, it gains a degree of Sub-Cooling

Question 12

Name the components of the Basic Refrigeration System

There are 4 components

Answer 12

-Compressor
-Condenser
-Thermal Expansion Valve (TEV)
-Evaporator

Question 13

What is the function of the Compressor?

Answer 13

-Pumps refrigerant around the system
-High Pressure, Hot Gas

Question 14

What is the function of the Condenser?

Answer 14

-Cools the refrigerant from a gas into a liquid using sea water
-High Pressure, Warm Liquid
-Refrigerant is Sub-Cooled

Question 15

What is the function of the Thermal Expansion Valve?

Answer 15

-Controls the flowrate of the refrigerant around the system, increasing or decreasing the output depending on the temperature of the coolant leaving the evaporator
-Low Pressure, Very Cold Liquid

Question 16

What is the function of the Evaporator?

Answer 16

-Refrigerant absorbs heat from the surrounding area, changing the state from liquid into gas
-Low Pressure, Cool Gas
-Superheated

Question 17

Name the parts of the Applied Refrigeration System

There are 6 parts

Answer 17

-LP cut out
-HP cut out
-Oil Seperator
-Liquid Receiver
-Drier
-Sight Glass

Question 18

What is the purpose of the LP cut out?

Answer 18

Stops the compressor if the pressure drops too low

Question 19

What is the purpose of the HP cut out?

Answer 19

Stops the compressor if the pressure gets too high

Question 20

What is the purpose of the oil seperator?

Answer 20

Seperates oil from the refrigerant

Question 21

What is the purpose of the Liquid Receiver?

Answer 21

Stores refrigerant during maintenance

Question 22

What is the purpose of the Drier?

Answer 22

Removes moisture from the refrigerant

Question 23

What is the purpose of the Sight Glass?

Answer 23

Indicates moisture in the refrigerant
Yellow = Moisture
Green = No Moisture

Question 24

What are the different Refrigeration Procedures?

There are 3 procedures

Answer 24

-Defrosting
-Leak Detection
-Lubrication

Question 25

Describe the Defrosting procedure

Answer 25

-Required when ice builds up on the evaporator coils
-Natural Defrost: Carried out every 3 to 6 months
-Hot Gas Defrosting: Carried out for a maximum of 1 hour per day, usually in 15 minute intervals
-Electrical Heating Coils: Carried out for a maximum of 1 hour per day

Question 26

Describe the Leak Detection Procedure

Answer 26

-Oil Slicks: When oil is leaking, refrigerant will also be leaking
-IRLDS infra-red leak detection system
-Spectrolyne Dye and UV Lamp
-Snoop (similar to soapy water)
-Halogen Leak Detector (handheld electronic device)

Question 27

Describe the Lubrication procedure

Answer 27

-Lubricants used are Hygroscopic (absorb moisture from the atmosphere)
-Oil is added to the compressor in these ways:
1)Via Sump Filler Plug
2)Via a hand pump
3)Via the use of a Dosing Pot

Question 28

Give a brief decription of the Montreal Project

Answer 28

An agreement to phase out harming ozone depleting substances/refrigerants such as: CFCs, HCFC, Halons

Question 29

Give a brief description of the Kyoto Protocol

Answer 29

An agreement to reduce all greenhouse gases such as: CO2, HFC, PFC

Question 30

What are the hazards involved with refrigerants?

Answer 30

-They are heavier than air and will displace oxygen
-If exposed to high temperatures, they can produce Phosgene gas
-Can produce cold burns on exposed skin (frost bite)
-Decomposing Fruit and Veg can produce CO2

Question 31

What are some of the health and safety risks when dealing with refrigerant?

Answer 31

-If refrigerant gets into the eyes, they need flushing with running water and then medical attention is required
-Refrigerant on the skin requires washing off immediately

Question 32

What is the procedure for entering Refrigeration Compartments?

Answer 32

-The rating in charge of the watch is to be informed that personnel are entering the compartment, and informed when the compartment is vacated
-Breathing apparatus is available at the machinery space access
-The high and low exhaust fans are running
-No smoking at any time in the refrigeration area. Any hot work is to be very tightly controlled
-The Infra-Red Leak Detection System (IRLDS) is working correctly and indicating safe
-The personnel trapped warning lamps are in working order
-Any rating entering the room is to be accompanied by another rating who remains outside the room as a safety number
-The internal door opening mechanism is in correct working order

Question 33

What does chilled water provide cooling for?

Answer 33

-Weapons Systems
-Radars
-Ships Computer Systems
-ATUs

Question 34

What is the major difference between the components of a refrigeration and chilled water plant?

Answer 34

The chilled water plant has a chiller in the place of an evaporator