VAPOUR ABSORPTION REFRIGERATION SYSTEM

 PRINCIPLE : 

                           The vapour absorption system has no compressor. The compressor is replaced by the combined effects provided by an Absorber , Pump and Generator. The compressor work is replaced by the heat supplied in the generator and pump. The pump consumes less electric power. The generator is operated by the external heat source. 

ABSORBENT - It absorbs refrigerant in the vapour phase and convert into liquid phase. 

REFRIGERANT - Ammonia is used as the refrigerant. 

AQUA - AMMONIA SYSTEM - It used the homogenous mixture of ammonia and water. Hence it is called as aqua-ammonia system.

 DESCRIPTION :

                EVAPORATOR - It consist of coiled tubes. The substance to be cooled is paced in the evaporator. It is the coldest region in the refrigerator. It is also called refrigerated space or freezer compartments.

               ABSORBER TANK - It contain the absorbent. It should have high affinity for the refrigerant, high boiling point and low specific heat.

               CIRCULATION PUMP- The pump circulates the refrigerant to the generator.

               GENERATOR - Heat is added to the generator from an external source. It may be a gas burner or solar heater.

               CONDENSER - Air or water is used as the cooling medium.

                  EXPENSION VALVE - The condenser is connected to an expansion valve. The pressure of the liquid passing through the expansion valve drops for reuse in the evaporator.

WORKING :

• The dry low pressure ammonia vapour from the evaporator enters the absorber.

• The absorber contain the cold water. Dry ammonia vapour is absorbed in the cold water producing a low pressure concentrated ammonia solution.

• The circulation pump pumps the strong ammonia solution from the absorber to the generator. This action increase the pressure of the solution.

• In the Generator, the solution is heated by external heat source (solar).

• Hence the high pressure ammonia vapour enters the condenser (concentrated ammonia solution).

• The weak ammonia solution in the generator come back to the absorber. 

• In the condenser, cold water is circulated around the condenser tubes. So the ammonia vapour is condensed to liquid ammonia.

• The high pressure liquid ammonia is passed to the expansion valve for reduce the pressure.

• The low pressure low temperature Ammonia liquid is passed to the evaporator in the freezer compartment . 

• The resultant ammonia vapour from the evaporator to the absorber.