Final answer:
The Latent heat of vaporization is the primary type of heat transfer in an evaporator. It occurs without a temperature change, enabling a phase transition from liquid to vapor. Condensation is the reverse, releasing the same amount of latent heat.
Step-by-step explanation:
The heat that represents nearly all the heat transfer that takes place in the evaporator is called the Latent heat of vaporization. During the process of vaporization, heat is transferred to a liquid from its surroundings without a temperature change in the system, leading to a phase change from liquid to vapor. Conversely, condensation is the reverse process, releasing the latent heat, which is the same amount absorbed during vaporization, thus causing the surrounding temperature to increase.
When a vapor condenses, it transfers energy away to a colder surface, resulting in the release of the latent heat. The calculation for this energy transfer for both vaporization and condensation can be expressed as Q = mLy, where Q is the heat transfer, m is the mass of the substance, and Ly is the latent heat of vaporization or condensation. Notably, for a substance, the molar heat of vaporization and the molar heat of condensation have the same magnitude but opposite signs.