Simple Vapour Absorption System
What is Simple Vapour Absorption System?
Simple Vapour Absorption System utilizes heat energy rather than mechanical energy. In Vapour Absorption System, absorber, a pump a generator and a pressure reducing valve replace compressor. These parts play out a similar capacity as that of a compressor. In this system, vapour refrigerant comes out from the evaporator. The absorber absorbs the vapour refrigerant. It is absorbed by the weaker solution of refrigerant and forming a solution. The strong solution is pumped to the generator. It is heated by some external force. During the heating process, the vapour refrigerant is driven off by the solution. Then, it enters into the condenser where it is liquefied. The liquid refrigerant flows into the evaporator and completes the cycle. It consist of:
- an absorber
- a pump
- a generator
- a pressure reducing valve
- expansion valve
Working of the Simple Vapour absorption System
- In this system, the low-pressure ammonia vapour leaves the evaporator. Coldwater in the absorber absorbs the low-pressure ammonia vapour.
- Water lowers the pressure of ammonia in the absorber. Therefore, it draws more of ammonia vapour from the evaporator. The overall temperature of the solution is increased.
- The heat of the solution is removed by the cooling arrangement in the absorber. Water`s absorption capacity is increased. At high-temperature water absorbs less ammonia.
- The liquid pump pumps the strong solution to the generator. The ammonia in the generator is heated by som force, for example, steam or gas.
- During the heating procedure, the ammonia vapour is driven off the arrangement at high pressure. It leaves behind the weak ammonia solution in the generator.
- Weak ammonia solution flows into the absorber at low pressure after passing through the pressure reducing valve.
- High-pressure ammonia vapour from the generator is condensed in the condenser to a high-pressure liquid ammonia.
- This liquid ammonia is passed to the expansion valve through the receiver and then to the evaporator. This completes the simple vapour absorption cycle.
C.O.P of the Simple Vapour absorption System
In this system, the heat consumed by the refrigerant in the evaporator gives the refrigerating effect. The total energy supplied to the system is the sum of work done by the pump and the heat supplied in the generator. Therefore Coefficient of performance of the system is given by
= Heat absorbed in evaporator / Work done by pump + Heat supplied in generator