Which refrigerant state indicates that the system is ready to absorb heat?

The state of saturated vapor indicates that the refrigerant is ready to absorb heat effectively. In a refrigeration cycle, saturated vapor is the state of the refrigerant just before it enters the compressor. At this point, the refrigerant has absorbed as much heat as it can hold at a given pressure and temperature, making it ideal for the process of heat absorption.

When the refrigerant vapor becomes saturated, it is at a balance between being a liquid and a gas, which allows it to absorb additional heat without a change in temperature. As the saturated vapor enters the compressor, it is then compressed, increasing its pressure and temperature, and thereby readying it for the next stage of the refrigeration cycle.

In contrast, while other states such as the subcooled liquid, superheated vapor, and saturated liquid have their own roles in the refrigeration cycle, they do not represent the optimal state for heat absorption in the way that saturated vapor does. A subcooled liquid is designed to avoid boiling in the evaporator, while superheated vapor has already absorbed heat to a point where it is warmer than its saturation temperature at that pressure, and a saturated liquid is ready to vaporize but is not in the best condition to absorb additional heat efficiently.