Question

Vapour Absorption Refrigeration System, normally uses refrigerant.

• A. R-12
• B. R-22
• C. R-134a
• D. R-717

Hint:

If a question asks about Absorption systems, think of Ammonia. Then remember that Ammonia is R-717 because its molecular weight is 17 ($N=14, H=1 \times 3$).

Answer 1

The Correct Option is D

Vapour Absorption Refrigeration Systems (VARS) differ from compression systems by using a physical or chemical absorption process to move refrigerant. These systems require a pair of fluids: a refrigerant and an absorbent. 1. The Ammonia-Water Pair: The most common pair used in industrial absorption systems is the

Ammonia-Water system.

• Refrigerant: Ammonia acts as the refrigerant because of its excellent thermodynamic properties and high latent heat.

• Absorbent: Water acts as the absorbent because it has a very high affinity for ammonia.

2. Identifying R-717: In the international refrigerant numbering system:

• R-717 is the chemical designation for

Ammonia ($NH_3$).

• The '700' series is used for inorganic refrigerants, and '17' is the molecular weight of ammonia.

3. Why it is Preferred for VARS: Ammonia is highly soluble in water at low temperatures and can be easily separated at higher temperatures in the generator. This makes it the standard choice for absorption cycles, which are often powered by waste heat rather than mechanical compressors.