Refrigeration is the process of lowering down the temperature of the body than its surrounding temperature, by extracting an amount of heat from it.
Now the question arises, what is the difference between a cooling process and a refrigeration process?
The Cooling process is the spontaneous process where the final temperature of the body need not be lower than the surrounding temperature. Whereas, in the case of Refrigeration, it is not a spontaneous process where the final temperature of the body should always be lower than the surrounding temperature.
Consider, a cup of hot tea is placed on the top of the table. After some time, you will be noticed that the temperature of the tea becomes equals to the surrounding temperature. This is an example of the cooling process. For the refrigeration process, consider a glass containing water and you put a lot of ice in it. You will be noticed that the temperature of the glass is lowered than the surrounding temperature.
There are many areas where refrigeration plays a vital role, namely: Food processing and preservation, Chemical industries, Conditioning of air, Freshwater installations, Ice production, Transport refrigeration, etc.
Now the refrigeration process can be done by the movement of refrigerant (a fluid that takes heat from the body that needs to be cooled down than the surrounding temperature) from four components: Evaporator, Compressor, Condenser & Expansion device.
The following process diagram can easily depict the refrigeration process.
It is a component of the refrigeration cycle in which latent heat is taken by the refrigerant that flows in the tubes of the evaporator from the objects which are placed in the evaporator. After taking the latent heat from the object, the phase of the refrigerant has changed into the dry gas and moves towards the compressor. Another purpose of this component is to receive the low pressure and low-temperature refrigerant fluid from the expansion valve.
It is the most important component of the refrigeration cycle. The compressor compresses the refrigerant to the pressure that corresponds to the saturation temperature which is higher than the temperature at the entry point of the compressor. Moreover, the capacity of the refrigeration mainly depends upon the capacity of the compressor.
In a cycle of the refrigeration system, the condenser plays a vital role. The high temperature, high pressurized refrigerant vapor from the compressor is entered into the condenser where the phase change of refrigerant occurs. The vapor phase of the refrigerant is changed into the liquid phase by rejecting the heat present in the vaporized refrigerant.
4. Expansion Valve
The important function of the expansion valve is that it removes the pressure from the liquid refrigerant that coming from the condenser. Moreover, the high pressurized refrigerant when entering into the expansion valve, its temperature is quite high.