Various defrosting techniques used in Refrigeration and Air conditioning

In every AC and refrigeration unit, we want a fluent transfer of heat. Four methods which can be implied to get rid of Frost which is a hindrance to the heat transfer and has a negative impact on refrigeration systems.

These include

1.      Defrosting using Hot Water

2.      Electric heating

3.      Defrosting through reverse refrigeration cycle

4.      Defrosting through hot gases

Defrosting using Hot Water:

As the name clearly indicates, in this method water with high temperature is passed to melt the water vapors which are present deposited as frost. The heat flows from hot water and melts the frost.

Electric Heating:

In this apparatus, some coils are present inside the evaporator. These coils do not contain any fluid. These coils are used for Electric heating purpose. When the current is passed through these coils, heat is generated due to the resistance of the coils which can be calculated as

                                               

P = I² R

This heat then melts the frost from the evaporator.

Defrosting through reverse refrigeration cycle:

This apparatus has been provided with a four way valve system. By this valve, we can bring appreciable changes in the apparatus. Evaporator can be converted to Condenser and the condenser then behaves as Evaporator.

By doing so, if evaporator is converted into condenser, it will release heat to the surrounding. This heat will melt the pre existing layer of the frost.

Defrosting through Hot gases:

The compressed gases (refrigerant) have a high temperature inside the compressor. In this apparatus, we possess a solenoid valve. By opening this valve, these high temperature, high pressure refrigerant can be introduced inside the evaporator.

By doing so, the heat from these hot gases will flow to the low temperature side and will eventually result in melting of the frost.