Working of Vapour Compression Refrigeration System (VCRS)

Working of Vapour Compression Refrigeration System (VCRS)

The various refrigeration system which exists are given below:-

1.  Ice refrigeration system
2.  Air refrigeration system
3.  Vapour compression refrigeration system
4.  Vapour absorption refrigeration system
5.  Special type system-
     a} Thermoelectric refrigeration system
     b} Cascade refrigeration system
     c} Adsorption refrigeration system
     d} Vortex tube refrigeration system
     e} Steam jet refrigeration system
     f} Mixed refrigeration system
            Out of all these refrigeration system Vapour Compression Refrigeration System is mostly used and most important.
Simple vapour compression system


It is the most usable and practical form of refrigeration.It is the most vital refrigeration system from the view point of commercial as well as domestic utility.
           Here refrigerant evaporates and condenses or changes alternately between the liquid and vapour phases without leaving the refrigeration space.

working principle

During evaporation process,it absorbs heat from the low temperature{cold} body.This heat is wisely used as its latent heat for transforming it from the liquid to vapour refrigerant.
                             In cooling or condensing,it rejects or release heat to external body,by which creating a cooling/liquifying effect in the working fluid.
              Thus we say that VCRS acts as a latent heat pump as it pumps its latent heat from the cold body and delivers it to the external hot body or cooling medium.

functions and utilization of different parts of a vapour compression cycle

– It is a mechanical device which is used to increase both pressure and temperature  of a refrigerant.
– It is a work absorbing device in which energy is transformed in to working  fluid.
– Here piston reciprocating compressor is used.
   Generally three types of valves used in VCRS-
a} Ring valve-   pressure 60mpa and speed 600r.p.m.
b} Plate valve-   pressure 40mpa and speed 800r.p.m.
c} Poppet valve-pressure 30mpa and speed 600r.p.m.
2.} Condenser:- 
– It is a type of heat exchanger in which heat is rejected by refrigerant to the surrounding.
– It is present to the side of a refrigerator in the form of bunch of tubes.
 – Generally condenser tubes are made of COPPER.
3.}Expansion or throttle valve:-
– It is generally known as the pressure reducing device which reduces pressure of  refrigerant and thus reduce its temperature.
– Here blow of refrigerant occur through a restricted passage.
– Its main work is to control the flow of refrigerant.
– It is an isenthalpic process i.e. enthalpy remains  constant.
e.g. capillary tube{domestic},shutter valve,gate valve etc.
It is also a type of heat exchanger in which heat is absorbed by refrigerant at constant pressure.It is also made up of of COPPER.
5.} Discharge line:-
A discharge line delivers the high pressure and high temperature vapour from the compressor to the condenser.
6.}Receiver tank:-
It is used to provide storage for a condense liquid,so that a constant supply of liquid is available to the evaporator as required.
7.}Liquid line:-
A liquid line carries a liquid refrigerant from the receiver tank to the expansion or throttle valve.
8.}Suction line:-
The suction line provides/brings the low pressure vapour from the evaporator to the suction inlet of compressor.

Working cycle diagram


T-S And P-H Diagram




Merits and demerits of vapour compression refrigeration system over air refrigeration system:-

1.} Here coefficient of performance{cop}is quite high as in VCRS the working cycle is very closed to reversed carnot cycle.
2.} Here the size of evaporator is smaller for the same refrigerating effect.
3.} Its running cost is also lower as compare to air refrigeration system when used on ground level.Its almost 1/4 of air refrigeration system.
4.} Temperature of evaporator can be achieved simply as per requirement by the adjustment of throttle valve for same unit.
1.} Its initial cost is high.
2.} The major disadvantage is leakage  of  vapour, inflammability and toxity.
That was all about the Working of Vapour Compression Refrigeration System ( VCRS ).
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