Refrigeration Flashcards
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.
3 types of Heat transfer?
Conduction
Convection
Radiation
Describe Conduction?
Heat transfer through a solid
Describe convection?
Heat transfer through a fluid.
Describe Radiation?
Heat transfer through a space.
Describe sensible heat?
Heat required to change temp not change state of substance.
Describe latent heat?
Heat required to change state of substance not the temp.
Describe superheat?
Substance goes above boiling point it is superheated. Every degree in heat gains 1 point degree of superheat.
Describe sub-cooling?
Substance cools and condenses into liquid then drops below its boiling point.
4part refrigeration components?
Compressor
Condenser
Thermal expansion valve (TEV)
Evaporator
Function of compressor?
Pumps refrigerant around the system.
Function of condenser?
Used sea water too cool the refrigerant changing its state from a gas into a liquid.
Function of a (TEV)?
Controls flow rate of refrigerant through a system increase and decrease flow depending on temp of refrigerant leaving evaporator.
Function of evaporator?
Refrigerant flowing through evaporator removes heat from refrigerator changes state from liquid to gas.
LP cut out?
Stops compressor if pressure drops.
HP cut out?
Stops compressor if pressure gets too high.
Oil separator?
Separates oil from the refrigerant.
Liquid receiver?
Stores refrigerant during maintenance.
Function of Drier?
Removes moisture from refrigerant.
Sight glass?
Indicates moisture in the refrigerant
Yellow - there is moisture
Green - there isn’t moisture
Methods of defrosting?
Natural defrost- every 3 to 6 months
Hot gas defrost- maximum of 1 hour in 15 minute slots.
Electric heating coils- same as hot gas.
Methods of leak detection?
Oil slicks Infra-red leak detection system Spectrolyne dye and UV lamp Snoop Halogen leak detector
3 lubricants?
OM70
SW68
Suniso 3GS
Ways oil is added to the compressor?
Via sump filler plug
By a hand pump
Through the use of a dosing pot
Montreal protocol?
CFC
HCFC
HALONS
Kyoto summit - reduce greenhouse gasses.
Greenhouse gasses?
CO2
HFC
PFC
What is chilled water used for?
Weapon systems
Radars
Ships computer systems
Air treatment units (ATU)