Domestic vapour-compression refrigerators – Common working fluid Historically, which refrigerant has been most commonly used in domestic vapour-compression refrigerators?

Introduction / Context:
Refrigerant selection in domestic refrigerators balances safety, efficiency, materials compatibility, and compressor technology. Understanding legacy choices helps interpret older equipment and exam conventions.

Given Data / Assumptions:

• Question follows traditional textbook history (pre-phaseout era).
• Focus on domestic, hermetic, small-capacity refrigerators.

Concept / Approach:
For decades, R-12 (dichlorodifluoromethane) dominated household refrigerators due to favorable pressures, chemical stability, and compatibility with mineral oils. Modern units often use isobutane (R-600a), but in classic exam contexts, R-12 is the expected answer.

Step-by-Step Solution:
Identify typical historical domestic refrigerant: R-12.Ammonia is toxic and used in industrial plants; CO₂ requires high pressures.Hence, choose R-12.

Verification / Alternative check:
Manufacturer data sheets and regulatory histories show broad R-12 use before environmental phaseouts under Montreal Protocol, later replaced by HFCs/HFOs or hydrocarbons.

Why Other Options Are Wrong:

• Ammonia and CO₂ are not common in small domestic hermetic refrigerators (safety/high pressure constraints).
• “All of these” and unusual blends are incorrect historically.

Common Pitfalls:
Applying current eco-refrigerant trends (e.g., R-600a) to legacy-oriented questions without noting historical context.

Final Answer:
R-12