Liquid refrigerant that has passed through a metering device is?

• A. High pressure vapor
• B. Low pressure saturated liquid
• C. Superheated vapor
• D. Two-phase mixture

Answer: (B)

Metering devices throttle the high‑pressure liquid, dropping its pressure to the evaporator level while leaving its enthalpy about the same. At this lower pressure, the liquid is at its saturation temperature for that pressure, i.e., a low‑pressure saturated liquid. This is why the refrigerant leaving the metering device is described as a low‑pressure saturated liquid—it’s ready to begin boiling as it enters the evaporator, where heat absorption will create a two‑phase mixture. High‑pressure vapor or superheated vapor are states not produced by the throttling process, and while a two‑phase mixture forms in the evaporator, the immediate state after the metering device is the low‑pressure saturated liquid.