What happens to liquid refrigerant when pressure is decreased?

When the pressure of a liquid refrigerant is decreased, it will indeed evaporate. This process is based on principles from thermodynamics: when the pressure is lowered, the boiling point of the refrigerant also decreases. As a result, the refrigerant can transition from a liquid state to a gaseous state even at lower temperatures.

This behavior is crucial in refrigeration systems where the rapid change in state from liquid to gas is utilized to absorb heat, thus cooling the surrounding environment. This phenomenon is often observed in systems using evaporators, where the refrigerant is allowed to evaporate at low pressure, enabling effective cooling.

In the context of the other options, while solidification could occur under certain conditions, consistently lowering pressure typically promotes vaporization rather than solidification or increased density. The change to gas naturally follows as part of the evaporation process, but the primary outcome of reduced pressure on liquid refrigerant is its transition to a gas.