Refrigeration Flashcards
Pressure, Volume, Energy statement for boiling liquids.
As Pressure Increases, Volume Decreases and More Energy is required to boil a liquid.
As Pressure Decreases, Volume Increases and Less Energy is required to boil a liquid.
Explain heat transfer and 3 ways heat can be transferred.
Heat always travels from a Hot body to a Cold body, Heat can be transferred by Conduction, Convection, Radiation.
Explain Conduction.
Heat transfers through a Solid.
Explain Convection.
Heat transfers through a Fluid.
Explain Radiation.
Heat transfers through a Space.
Explain Sensible Heat.
This is the heat required to change temperature, not change the state of the substance.
Explain Latent Heat.
This is the Heat required to change the state of a substance without any change in its temperature.
Explain Superheat.
When a substance goes above its boiling point.
Explain Sub-cooling.
When a substance drops below its boiling point.
4 Components of Basic refrigeration system.
Compressor, Condenser, Thermal Expansion Valve (TEV), Evaporator.
What is the function of the Compressor?
Pumps refrigerant around the system.
What is the function of the Condenser?
Uses sea water to cool the refrigerant changing its state from a Gas into a Liquid.
What is the function of the Thermal Expansion Valve (TEV)?
Controls the flowrate of refrigerant through the system. Increasing or decreasing the flow depending on the temperature of the refrigerant leaving the Evaporator.
What is the function of the Evaporator?
The refrigerant flowing through the Evaporator removes heat from the refrigerant/cold room. This action changes the state of the refrigerant from a Liquid into a Gas.
Fuction of the LP cut out?
Stops the compressor if the pressure drops too low.
Function of the HP cut out?
Stops the compressor if the pressure gets too high.
Function of the Oil Seperator?
Seperates oil from the refrigerant.
Function of the Drier?
Removes moisture from the refrigerant.
Function of the Sight Glass and what does it indicate?
Indicates moisture in the refrigerant,
Yellow - there is moisture.
Green - there is no moisture.
Name 3 Methods of defrosting.
Natural Defrost, Hot Gas Defrost, Electrical Heating Cells.
When is Natural Defrost carried out?
Every 3 to 6 months.
When is Hot Gas Defrosting carried out?
Done for a maximum of 1 hour in 24 in 15 minute slots.
When is Electrical Heat Cells defrosting carried out?
Done for a maximum of 1 hour in 24.
Name 5 methods of Leak Detection.
Oils Slicks, Infra-red leak detection system (IRDLS), Spectrolyne Dye and UV Lamp, Snoop, Halogen Leak Detector.
