Flashing

Definition

The sudden partial vaporization of a liquid when its pressure drops below its saturation pressure.

At the expansion valve, the pressure drop causes part of the refrigerant to flash to vapor, which lowers the saturation temperature and chills the remaining liquid. This makes the refrigerant cold enough to absorb heat in the evaporator. Flashing is the mechanism by which throttling produces cold without external heat removal.

Related concepts

Pressure control of phase change · Expansion valve · Refrigerant cycle

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Part of The Blueprint of Water · 🔥 thermodynamics