Refrigeration is a process/system by which the temperature of a space is reduced [heat is removed from a space]
Principle of Refrigeration
When a liquid evaporates it produces a cooling effect by taking the heat from the surrounding
Examples:
- Place a drop of volatile liquid [ether (or) eau-de-cologne]on the hand
It gives a cooling sensation
This is because, the liquid evaporates taking the heat from the skin
- Water kept in an earthen/mud pot or pail, gets cooled
This is because, the water that gets leaked through the pores in the body/surface of the pot evaporates taking the heat from the body/surface of the pot/the water inside
- Take a cylinder containing liquid CO2
Place a Bottle of Water on the coiled outlet pipe of the cylinder
Open the outlet valve of the cylinder to release the CO2
Water in the Bottle gets cooled
This is because, the liquid CO2 evaporates taking the heat from the Bottle surface/Water inside
Compression Refrigeration Cycle – Vapour Compression System
Components & Operation
In the previous example – Liquid CO2 in the Cyl will soon become empty
Cooling effect will Stop
To continue the cooling effect the cylinder has to be recharged with CO2
In the actual Vapour Compression System, the Refrigerant vapours are not allowed to escape into atmosphere.
Instead it is compressed in a compressor
Pressurised refrigerant vapours are then cooled in a condenser to form liquid
Liquid Refrigerant is collected in a receiver
It is then sent back to the evaporator coil through a Throttle Valve (Expansion Valve)
This cycle is continued
In the actual Refer system, instead of cooling a bottle of water the cargo/provision is cooled, by using a fan to circulate the air around the evaporator coil and the cargo/provision
The liquid refrigerant inside the evaporator coil gets vapourised by taking the heat from the cargo
