Refrigeration and Air Conditioning Practice Test: Vapour Absorption Refrigeration System — Flashcards

Vapour Absorption Refrigeration System topics include:  ideal VAR system and its performance, domestic electrolux and lithium bromide refrigeration system.

A vapor absorption refrigeration system (VARS) is a refrigeration method that uses heat energy to change the condition of refrigerant vapors.  Basically, a VARS is a heat pump with three thermal reservoirs. It uses the principle that liquids evaporate at low temperatures when the pressure is reduced. 

A basic VARS setup includes the following components: Absorber, Pump, Generator, Pressure relief valve, Condenser, Expansion device, Evaporator. 

Here's how a VARS works:
Refrigerant vapors evaporate
The vapors enter the absorber and get absorbed by an absorbent
The pump pressurizes the rich refrigerant-absorbent solution from the absorber pressure to the generator pressure
In the generator, the solution is heated by available low-grade heat
As a result of heating, ammonia gas gets expelled from the strong solution in the generator and passes onto the condenser
In the condenser, the ammonia gas is again condensed to liquid and passed on to receiver
An analyzer separates water particles from ammonia vapor and only lets ammonia to pass through to the next components
The residue weak solution of water and ammonia accumulated in the generator is passed back to the absorber 

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