Basic Principle and working of Marine Refrigeration and A/C

Refrigeration and A/C working under 2 principles

> Liquids absorb heat when changed from liquid to gas

> Gases give off heat when changed from gas to liquid.

There are four main components of refrigeration or air conditioner.

> Compressor

     A compressor, basically compress the refrigerant gas thereby increase its pressure and temperature

> Condenser

     All the heat from refrigeration gas is absorbed by the condenser and changes its phase from gas to liquid.

> Expansion valve 

      The expansion device is responsible for quickly driving the pressure of the refrigerant down so it can boil (evaporate) more easily in the evaporator

> Evaporator

       The evaporator cooling the air going to the space by boiling (evaporating) the refrigerant flowing through it 

Working

     Figure illustrates the basic components and operating cycles of a refrigerator. Cold liquid refrigerant is evaporated in an evaporator coil which, being colder than its surroundings draws heat from them to latent heat of vaporization. The cool vapour is drawn off by a compressor which rises both the pressure and temperature of the vapour and passes it to the condenser. The pressure of the vapour having been increased, the vapour now has a temperature of condensation substantially greater than the temp of the condenser coolant liquid. The vapour is condensed to a high pressure liquid and the sensible heat of desuperheating  the vapour together with the intent heat of condensation is removed via the condenser coolant which is warmed up in the process. The high pressure liquid then passes through an expansion valve to the low pressure side of the refrigerator and, in doing so, flash evaporates to a two-phase mixture of cold liquid and vapour. The mixture then passes to the evaporator to continue the cycle.