Refrigeration Flashcards
Complete the sentence
When Pressure increases, Volume ____ and ____ Energy is required to boil a liquid
Volume Decreases
More Energy
Complete the sentence
When Pressure decreases, Volume ____ and ____ Energy is required to boil a liquid
Volume Increases
Less Energy
How does heat travel?
Hot to Cold
What ways can heat be transferred?
There are 3 ways
-Conduction
-Convection
-Radiation
Define Conduction
Heat transfer through a solid
Define Convection
Heat transfer through a fluid
Define Radiation
Heat transfer through a space
Define Sensible Heat
Heat required to change Temperature, not the State of a substance
Define Latent Heat
The heat required for a Change of State in a substance, while the Temperature remains constant
Define Superheat
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
Define Sub-Cooling
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
Name the components of the Basic Refrigeration System
There are 4 components
-Compressor
-Condenser
-Thermal Expansion Valve (TEV)
-Evaporator
What is the function of the Compressor?
-Pumps refrigerant around the system
-High Pressure, Hot Gas
What is the function of the Condenser?
-Cools the refrigerant from a gas into a liquid using sea water
-High Pressure, Warm Liquid
-Refrigerant is Sub-Cooled
What is the function of the Thermal Expansion Valve?
-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
What is the function of the Evaporator?
-Refrigerant absorbs heat from the surrounding area, changing the state from liquid into gas
-Low Pressure, Cool Gas
-Superheated
Name the parts of the Applied Refrigeration System
There are 6 parts
-LP cut out
-HP cut out
-Oil Seperator
-Liquid Receiver
-Drier
-Sight Glass
What is the purpose of the LP cut out?
Stops the compressor if the pressure drops too low
What is the purpose of the HP cut out?
Stops the compressor if the pressure gets too high
What is the purpose of the oil seperator?
Seperates oil from the refrigerant
What is the purpose of the Liquid Receiver?
Stores refrigerant during maintenance
What is the purpose of the Drier?
Removes moisture from the refrigerant
What is the purpose of the Sight Glass?
Indicates moisture in the refrigerant
Yellow = Moisture
Green = No Moisture
What are the different Refrigeration Procedures?
There are 3 procedures
-Defrosting
-Leak Detection
-Lubrication
Describe the Defrosting procedure
-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
Describe the Leak Detection Procedure
-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)
Describe the Lubrication procedure
-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
Give a brief decription of the Montreal Project
An agreement to phase out harming ozone depleting substances/refrigerants such as: CFCs, HCFC, Halons
Give a brief description of the Kyoto Protocol
An agreement to reduce all greenhouse gases such as: CO2, HFC, PFC
What are the hazards involved with refrigerants?
-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
What are some of the health and safety risks when dealing with refrigerant?
-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
What is the procedure for entering Refrigeration Compartments?
-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
What does chilled water provide cooling for?
-Weapons Systems
-Radars
-Ships Computer Systems
-ATUs
What is the major difference between the components of a refrigeration and chilled water plant?
The chilled water plant has a chiller in the place of an evaporator
