What is auto refrigeration?

• A. Rapid cooling of liquid when pressure is reduced by boiling instantly.
• B. The slow cooling of a system using external coolants.
• C. The process of minimizing heat through insulation alone.
• D. The cooling caused by environmental humidity.

Answer: (A)

Auto refrigeration is the self-induced cooling that happens when a liquid experiences a drop in pressure, causing part of it to flash into vapor. This vaporization absorbs latent heat from the remaining liquid, producing rapid cooling without any external coolant. That’s why the description “rapid cooling of liquid when pressure is reduced by boiling instantly” fits best—it captures the instantaneous boiling (flash evaporation) and the resulting cooling of the liquid. The other ideas describe cooling with external coolants, relying on insulation, or cooling from environmental humidity, none of which involve the liquid’s own phase change at a reduced pressure.