period one
Absorption Refrigeration Cycle
notes
reject heat
| heat energy in | |
' | & | |
| |
condenser | generator | |
expansion | pump | |
device | | |
evaporator | absorber | |
$ | % | |
| |
absorb heat | reject heat | Figure 6 |
| |
There are two fundamental differences between the absorption refrigeration cycle and the vapor-compression refrigeration cycle. The first is that the compressor is replaced by an absorber, pump, and generator. The second is that, in addition to the refrigerant, the absorption refrigeration cycle uses a secondary fluid, called the absorbent. The condenser, expansion device, and evaporator sections, however, are the same.
Refrigerant enters the evaporator in the form of a cool, low-pressure mixture of liquid and vapor ($). Heat is transferred from the relatively warm water to the refrigerant, causing the liquid refrigerant to boil. Using an analogy of the vapor- compression cycle, the absorber acts like the suction side of the compressor—it draws in the refrigerant vapor (%) to mix with the absorbent. The pump acts like the compression process itself—it pushes the mixture of refrigerant and absorbent up to the high-pressure side of the system. The generator acts like the discharge of the compressor—it delivers the refrigerant vapor (&) to the rest of the system.
The refrigerant vapor (&) leaving the generator enters the condenser, where heat is transferred to water at a lower temperature, causing the refrigerant vapor to condense into a liquid. This liquid refrigerant (') then flows to the expansion device, which creates a pressure drop that reduces the pressure of the refrigerant to that of the evaporator. The resulting mixture of liquid and vapor refrigerant ($) travels to the evaporator to repeat the cycle.
The components of the absorption refrigeration cycle will be discussed in detail in a moment.
