Simple Absorption System

Simple Absorption System Points : Simple Absorption System If the compressor in a vapour compression system were replaced with a generator is absorber assembly the result would be a simple absorption system.

In this case the low pressure refrigerant vapour (Ammonia) coming from the evaporator is absorbed in the absorber by the weak solution of refrigerant water. Absorption of ammonia lowers the pressure in the absorber, which in turn thaws more ammonia vapour from the evaporator. Some form of cooling arrangement usually water cooling, is employed in the absorber to remove the heat of solution evolved there. This is necessary to increase the absorption capacity of water because at high temperature, water absorbs less ammonia. The solution in the absorber is called a strong solution because it is rich in refrigerant. The pump draws strong solution from the absorbers, builds up a pressure up to 10 Kgf/cm² and forces the strong solution in the generator.

In the generator the strong solution of ammonia is heated by some external source such as gas or steam In the heating process the ammonia vapour I driven out of the solution as a high pressure vapour leaving behind in the generator a weak solution. The weak solution flows back to the absorber through a restriction which maintains the pressure differential between the high and low sides of the system. From the generator the refrigerant vapour is conducted to the condenser where it is condensed. Then the high pressure liquid ammonia is passed through a throttle valve to the evaporator where it absorbs its latent heat thus producing cold.