In what state does refrigerant typically enter the expansion valve?

The typical state in which refrigerant enters the expansion valve is as a saturated liquid. This is critical for the effective operation of the refrigeration cycle. In the expansion valve, the refrigerant undergoes a pressure drop, causing it to partially evaporate into a mixture of vapor and liquid. If the refrigerant were to enter the expansion valve in any state other than a saturated liquid, it could lead to inefficient cooling, system pressure imbalances, and potential damage to components, such as compressors.

Entering as a saturated liquid ensures that the refrigerant has the ideal properties to begin its phase change as it passes through the expansion valve. This process allows the refrigerant to absorb heat efficiently during the subsequent evaporation phase in the evaporator, which is essential for effective heat exchange in refrigeration systems.