Vapour Compression Refrigeration Cycle is the most widely used refrigeration system. In this system, the working fluid is a vapor. It readily evaporates and condenses or changes alternatively between the vapor and liquid phase without leaving the refrigerating plant.
During evaporation, it absorbs heat from the cold body and this heat is used as its latent heat for converting it from liquid to vapour whereas in Condensing or cooling, it rejects heat to external bodies, thus creating a cooling effect in the working fluid.
The figure above consists of the following five essential parts, those are:
The detailed explanation of the above parts is as follows.
The vapour at low pressure and low temperature enters the compressor from the evaporator where it is compressed to high pressure and high temperature.
This high pressure and temperature vapour refrigerant are discharged into the condenser through the discharge valve.
The condenser or cooler consists of coils of pipe in which the high pressure and temperature vapour refrigerant are cooled and condensed.
The refrigerant while passing through the condenser gives up its latent heat to the surroundings condensing medium which is normally air or water.
The condensed liquid refrigerant from the condenser is stored in a vessel known as a receiver from where it is supplied to the evaporator through the expansion valve.
It is also called a throttle valve. Its function is to allow the liquid refrigerant under high pressure and temperature to pass through it where it reduces its temperature and pressure.
It also consists of coils of pipe in which liquid-vapour refrigerant at low pressure and temperature is evaporated and converted into vapour refrigerant at low pressure and temperature.
The working of Vapor Compression Refrigeration System can be completed under 4 processes and are as follows.
The vapour at low temperature and low pressure enter the compressor where it is compressed isentropically and subsequently, its temperature and pressure considerably increase.
This vapour after leaving the compressor enters into the condenser, where it is condensed into high-pressure liquid and is collected in a receiver tank.
From the receiver tank, it passes through the expansion valve, where it is throttled down to low pressure and temperature.
After finding its way through an expansion valve, it finally passes onto the evaporator, where it extracts heat from the surroundings or circulating fluid and vaporizes to lower pressure vapour.
If expansion takes place without throttling, temperature level drops to a very low level due to which it should undergo sensible heat and latent heat in order to reach the evaporation stage.
The Coefficient of Performance(C.O.P) of a Simple Vapor Refrigeration Cycle is as follows.
C.O.P. = (heat extracted or refrigerating effect)/Work done.
C.O.P. = (h2-h1)/(h3-h2)
C.O.P. = (h2-h4)/(h3-h2).
[h1=h4, since during throttling expansion 4-1, the total heat content remains unchanged.]
The types of Vapor Compression Cycles which are important from the subject point of view are as follows.
The Advantages of Vapor Compression Refrigeration system are as follows.
The disadvantages of Vapor Compression Refrigeration system are as follows.
The applications of Vapor Compression Refrigeration system are as follows.
This is the explanation of the Vapor Compression Refrigeration Cycle in a detailed way.
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