What happens during the phase change of refrigerant from liquid to vapor?

During the phase change of refrigerant from liquid to vapor, the substance absorbs heat from the environment. This process is known as evaporation or boiling, depending on the context. When the refrigerant, initially in a liquid state, absorbs heat energy, this energy is used to break the intermolecular bonds that hold the molecules together in the liquid state. As these bonds break, the refrigerant molecules gain kinetic energy and transition to the vapor phase.

This characteristic of absorbing heat during the phase change is fundamental to how refrigeration systems work. It allows the refrigerant to carry heat away from the area being cooled. For example, in an evaporator coil, the refrigerant absorbs heat from the surrounding air or liquid, thus cooling the environment.

While it may seem that a constant temperature is maintained during this phase change, the key aspect is the absorption of heat, as it is the heat input that allows the phase transition. The volume and pressure may change as the refrigerant vaporizes, but the primary focus during this specific phase change is the heat absorption that facilitates the transition from liquid to vapor.