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Mech Theory 4 > Refrigeration > Flashcards

Refrigeration Flashcards

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1
Q

Complete the sentence

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

A

Volume Decreases

More Energy

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2
Q

Complete the sentence

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

A

Volume Increases

Less Energy

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3
Q

How does heat travel?

A

Hot to Cold

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4
Q

What ways can heat be transferred?

There are 3 ways

A

-Conduction
-Convection
-Radiation

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5
Q

Define Conduction

A

Heat transfer through a solid

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6
Q

Define Convection

A

Heat transfer through a fluid

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7
Q

Define Radiation

A

Heat transfer through a space

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8
Q

Define Sensible Heat

A

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

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9
Q

Define Latent Heat

A

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

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10
Q

Define Superheat

A

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

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11
Q

Define Sub-Cooling

A

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

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12
Q

Name the components of the Basic Refrigeration System

There are 4 components

A

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

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13
Q

What is the function of the Compressor?

A

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

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14
Q

What is the function of the Condenser?

A

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

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15
Q

What is the function of the Thermal Expansion Valve?

A

-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

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16
Q

What is the function of the Evaporator?

A

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

17
Q

Name the parts of the Applied Refrigeration System

There are 6 parts

A

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

18
Q

What is the purpose of the LP cut out?

A

Stops the compressor if the pressure drops too low

19
Q

What is the purpose of the HP cut out?

A

Stops the compressor if the pressure gets too high

20
Q

What is the purpose of the oil seperator?

A

Seperates oil from the refrigerant

21
Q

What is the purpose of the Liquid Receiver?

A

Stores refrigerant during maintenance

22
Q

What is the purpose of the Drier?

A

Removes moisture from the refrigerant

23
Q

What is the purpose of the Sight Glass?

A

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

24
Q

What are the different Refrigeration Procedures?

There are 3 procedures

A

-Defrosting
-Leak Detection
-Lubrication

25
Q

Describe the Defrosting procedure

A

-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

26
Q

Describe the Leak Detection Procedure

A

-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)

27
Q

Describe the Lubrication procedure

A

-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

28
Q

Give a brief decription of the Montreal Project

A

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

29
Q

Give a brief description of the Kyoto Protocol

A

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

30
Q

What are the hazards involved with refrigerants?

A

-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

31
Q

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

A

-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

32
Q

What is the procedure for entering Refrigeration Compartments?

A

-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

33
Q

What does chilled water provide cooling for?

A

-Weapons Systems
-Radars
-Ships Computer Systems
-ATUs

34
Q

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

A

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

Mech Theory 4 (4 decks)

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