Industrial Refrigeration Flashcards
What is the vapour compression system of refrigeration?
compressor ➡️ condenser ➡️ metering device ➡️ evaporator
what are five hazards that exist when working with refrigeration systems?
high pressures
toxic gases
burns
freezing of flesh
electrical shock
True or False:
heat travels from hot to cold?
true
what is conduction?
heat transfer by physical contact
what is convection?
heat transfer by moving matter
what is radiation?
transfer of heat by electromagnetic waves
refrigeration is the process of moving ____________?
heat
what is sensible heat?
heat that can be measured with a thermometer.
what is latent heat?
heat that is added or removed to change state.
what are two ways to make a liquid boil?
add heat
lower the pressure
what are the four main components in the vapour compression refrigeration cycle?
compressor
condenser
metering device
evaporator
where is the heat from the surroundings added to the refrigeration?
in the evaporator
what is meant by the high side and the low side in the refrigeration cycle?
high pressure side and low pressure side
what is a hermetically sealed unit?
unit that is completely sealed from the atmosphere
why is nitrogen used when the refrigeration piping is welded?
so the inside of the pipe is kept as clean as possible from oxidization
what two things circulate through the refrigeration piping?
refrigerant
oil
the boiling temperature of a liquid and the condensing temperature of a vapour can be the same as long as the _____________ exerted on the fluid is the same
pressure
as it changes into a vapour, a liquid absorbs the _______________________
latent heat of vaporization
as it condenses into a liquid, a vapour rejects the _________________
latent heat of condensation
what should the first response be if a worker is splashed with liquid ammonia?
safety shower
on a flooded system, the brine tubes are immersed in the liquid _________________
refrigerant
all ammonia-flooded systems require an oil separator because the __________ does not return to the compressor.
oil
the liquid levels in liquid overfeed low-pressure receivers are monitored and controlled by_______________
float switches
lithium bromide (absorption) refrigeration uses ____________ energy to produce the refrigeration effect
heat
____________ is used as the refrigerant in the lithium bromide absorption system.
water
in the absorber, the solution becomes ____________ as it absorbs water vapour.
diluted
the concentrator drives the water vapour out of the lithium bromide solution by adding ___________ to the solution
heat
in an absorption system, the heat exchanger serves a vital function, it _________ the dilute solution and __________ the concentrated solution
heats
cools
cooling the concentrated solution too fast can cause _____________
crystallization
in order to shut down the absorption chiller safely, the system must run through the _____________ cycle to prevent crystallization
dilution
what are three common maintenance checks performed on condensers and evaporators?
leaks
fouling or plugging
piping connections
____________ analysis and treatment can prevent scale and algae build up in cooling towers
water
when performing an alignment on a refrigeration compressor and electric motor, you must account for ____________________
thermal growth
what five tools can assist you when performing maintenance checks on a compression refrigeration system?
thermometer
multimeter
pressure gauge
leak testing device
manual
the metering device on a compression refrigeration system can be a ____________, _______________ or a _____________
capillary tube
fixed orifice
thermostatically controlled expansion valve
what 3 symptoms indicate that the system is low on refrigerant?
inability to cool
iced up evaporator coil
warm air flow from ventilation ducting
name three methods of heat transfer
conduction
convection
radiation
what happens in the evaporator?
heat is taken in
liquid is evaporated into a gas
what happens in the condenser?
heat is rejected
gas is condensed into a liquid
what happens when we increase the pressure on a fluid being heated?
raise the boiling point
where is the lithium bromide concentration increased?
in the generator
what two units in the absorption system require cooling water?
absorber
condenser
what happens if the Li-Br solution becomes too concentrated?
it crystallizes
what is the dilution cycle used for?
slows down the cooling process so the lithium bromide does not crystallize
what unit is steam or hot water used in?
generator
what units consist of the low pressure system?
evaporator, condenser, metering device
where is the metering device located?
between the low and high pressure side
which has the higher boiling point? Water or Li-Br?
water
