basic principle of refrigeration is
simple
just pass a colder liquid continuously
around the object which is to be cooled
this will take heat out from the object
the whole refrigeration technology is
after this how to produce cold liquid
continuously
we will see how this is achieved in this
video
this is what inside a refrigerator
at the heart of the system is a simple
device called throttling device
cold liquid is produced with help of
this phenomenon
in this case throttling device is a
capillary tube
for effective throttling at inlet
refrigerant should be high pressure
liquid
throttling device is an obstruction to
the flow which causes tremendous
pressure drop
due to drop in pressure boiling point of
refrigerant comes down and it starts
evaporating
heat required for evaporation comes
within the refrigerant so its
temperature drops
if you check temperature across
throttling device you can notice this
drop
next phase is simple
just pass this cold liquid over the body
where you have to absorb heat
during heat absorption process
refrigerant further evaporates and
transforms into pure vapor
so we have produced the required
refrigeration effect
if we can take this low pressure vapor
refrigerant to state before throttling
process
that is high pressure liquid state we
will be able to repeat this process
so first step let's raise the pressure
a compressor is introduced for this
purpose
compressor will raise the pressure back
to its initial value
but since it is compressing gas along
with pressure temperature will also
raise
it is unavoidable
now the refrigerant is high pressure
vapor
to convert it to liquid state we are
introducing another heat exchanger
this heat exchanger is fitted outside
refrigerator
so it will liberate heat to the
surroundings
vapor will get condensed to liquid and
temperature will come down to normal
level
so the refrigerant is back to its
initial state again high pressure liquid
we can repeat this cycle over and over
for continuous refrigeration
this cycle is known as vapor compression
cycle
you can note more details of
refrigerator components here
to enhance heat transfer both evaporator
and condenser are having fins attached
to it
since evaporator is cooling the
surrounding air it is common that water
will get condensed over it forming frost
frequent removal of frost is required to
enhance heat transfer
apart from raising pressure compressor
also helps maintain flow in the
refrigerant circuit
usually hermetically sealed
reciprocating type with proper sealing
is used for this purpose
since it is compressing gas huge amount
of input power is required for this
operation
a simple energy balance of the system
yields this relation
performance of a refrigeration system
can be defined as follows
hope you had a good overview of working
of a refrigerator thank you