What is transferred from the refrigerated space to the refrigerant in the evaporator?

In the evaporator of a refrigeration system, the key process involves the transfer of heat from the refrigerated space to the refrigerant. This process primarily happens through the absorption of latent heat. Latent heat refers specifically to the heat energy required to change the state of a substance without changing its temperature—in this case, the refrigerant is evaporating from a liquid to a vapor as it absorbs heat from the surroundings.

When the refrigerant enters the evaporator as a low-pressure liquid, it absorbs heat from the space to be cooled. This heat is needed to convert the liquid refrigerant into a vapor. The latent heat absorbed during this phase change is what enables the refrigerant to effectively remove heat from the refrigerated space, thereby cooling it down.

Understanding this concept is crucial, as it highlights the roles of latent heat in refrigeration systems, distinguishing it from other heat types like sensible heat, which involves temperature change without phase change, and work energy, which pertains to physical work done on or by the system.