Domestic Electrolux Refrigerator

Introduction:-

  In the vapour absorption system, the compressor is replaced by an absorption, a pump and generator and a pressure reducing valve. This components in vapour absorption system, perform the same function as that of a compressor in vapour refrigerant from the evaporation is drawn into an absorber where it is absorb by the weak solution of the refrigerant forming a strong solution. This strong solution is pumped to the generator where it is heated by some external source. During the heating process the vapour refrigerant is driven off by the solution and enters into the condenser where it is liquefied. The liquid refrigerant, then close into the evaporation and this the cycle is completed.

Domestic Electrolux Refrigerator:-

      The idea was first developed by the ‘Electrolux company’ of Luton , England.

This type of refrigerator is also called three- fluid absorption system.

Main purpose of system:-

    Is to eliminate the pump so that in the absence of moving parts, the machine becomes noiseless. The three fluids used in this system are ammonia, hydrogen and water. The ammonia is used as a refrigerant because it possesses most of the desirable properties. It is toxic, but due to absence of moving parts, there is very little chance for the leakage and the total amount of refrigerant used is small.

Uses of Hydrogen:-    

     The hydrogen the lightest gas, is used to increase the rate of *evaporation of the liquid ammonia passing through the evaporator. The hydrogen is also non- corrosive and insoluble in water. This is used in the low- pressure side of the system. The water is used as a solvent because it has the ability to absorb ammonia readily . The principle of operation of a domestic Electrolux type refrigerator, as show in Fig. 1, is discussed below.

 

Uses of Ammonia:-   

   The strong ammonia solution from the absorber through heat exchanger is heated in the generator by applying heat from an external source, usually a gas burner. During this heating process, ammonia vapors are removed from the solution and passed to the condenser. A rectifier or a water separator fitted before the condenser removes water vapor carried with the ammonia vapors, so that dry ammonia vapors are supplied to the condenser.

Uses of Water vapors:-       

    These water vapors, if not removed, will enter into the evaporator causing freezing and choking of the machine. The hot weak solution left behind in the generator flows to the absorber through the heat exchanger. This hot weak solution while passing through the exchanger is cooled. The heat removed by the weak solution is utilized in raising the temperature of strong solution passing through the heat exchanger. In this way, the absorption is accelerated and the improvement in the performance of a plant is achieved.

      The ammonia vapors in the condenser are condensed by  using external cooling source. The liquid refrigerant leaving the condenser flows under gravity to the evaporator where it meets the hydrogen gas. The hydrogen gas which is being fed to the evaporator permits the liquid ammonia to evaporate at a low pressure and temperature according to Dalton’s principle.