What happens when heat is added to saturated liquid refrigerant?

When heat is added to a saturated liquid refrigerant, it leads to the phase change known as evaporation. In this state, the refrigerant is on the verge of transitioning from liquid to vapor. As heat is introduced, the temperature of the refrigerant rises, providing the energy needed for the liquid molecules to overcome the intermolecular forces that hold them together. This process transforms the liquid into vapor without an increase in temperature during the phase change, until all the liquid has evaporated.

In contrast, condensing would occur if heat were removed from a vapor, leading the refrigerant to switch back to a liquid state. Freezing would involve a phase change from liquid to solid, which typically happens at lower temperatures and does not apply when heat is added. Remaining stable would imply that the refrigerant is not undergoing any phase change, but that is not the case when heat is continuously supplied to a saturated liquid. Thus, the correct understanding highlights the natural progression from liquid to vapor upon heating within the confines of refrigeration cycles.