What is the condition of the refrigerant as it leaves the expansion valve?

The correct choice indicates that the refrigerant, as it exits the expansion valve, is in a state of saturated liquid and vapor. This condition occurs because the expansion valve is designed to reduce the pressure of the refrigerant, which allows a portion of the refrigerant to evaporate, creating a mixture of both liquid and vapor.

In a refrigeration cycle, before the refrigerant enters the expansion device, it is typically a high-pressure liquid. The expansion valve reduces the pressure, which causes the refrigerant to partially vaporize due to the drop in temperature and pressure. This results in a phase change where some of the refrigerant remains in liquid form while some converts to vapor, leading to the saturated state.

This mixture is crucial for the efficiency of the system as it ensures that there is sufficient vapor present to absorb heat in the evaporator coil. Thus, having a mixture of saturated liquid and vapor as the refrigerant leaves the expansion valve sets the stage for effective heat exchange in the subsequent stages of the refrigeration cycle.