Absorption versus compression refrigeration In a vapour absorption refrigeration system, what components collectively replace the mechanical compressor of a vapour-compression system?

Introduction / Context:
Absorption refrigeration uses thermal energy rather than mechanical work for compression. Understanding the functional substitution of components helps in system selection where waste heat is available.

Given Data / Assumptions:

• Working pair examples: NH3–H2O or LiBr–H2O.
• Steady operation; throttling devices present similar to compression systems.

Concept / Approach:
Instead of mechanically compressing refrigerant vapour, absorption systems chemically absorb the refrigerant into an absorbent (absorber), pump the liquid solution to high pressure (liquid pump), and then desorb the refrigerant vapour using heat (generator). The rectifier/analyzer may also be present depending on the pair.

Step-by-Step Solution:
Absorber: low-pressure vapour is absorbed, releasing heat.Pump: raises pressure of the solution (low power due to liquid pumping).Generator: heat input liberates high-pressure refrigerant vapour, functionally equivalent to compressor discharge.

Verification / Alternative check:
Thermodynamic cycles show the compressor work in vapour-compression is replaced by pump work plus generator heat input in absorption cycles.

Why Other Options Are Wrong:

• Liquid pump only or generator only cannot accomplish both pressurization and vapour production functions.
• Absorber and generator without pump cannot raise pressure.

Common Pitfalls:
Ignoring the crucial role of the liquid pump in achieving high pressure with minimal mechanical work.

Final Answer:
Absorber, generator, and liquid pump