What kind of heat produces a change in state without a change in temperature?

The concept of latent heat is crucial in understanding phase changes within substances. Latent heat refers to the amount of heat energy required to change a substance from one state to another—such as from solid to liquid (melting) or from liquid to gas (vaporization)—without changing its temperature. This is important in applications involving refrigeration and air conditioning because it helps to explain how systems transfer heat during phase change processes.

For instance, when ice melts into water, it absorbs heat (latent heat) from its surroundings without any increase in temperature until it has completely transitioned into water. Similarly, when water evaporates to become steam, it also takes in thermal energy but remains at the same temperature until the phase change is complete.

In contrast, the other options relate to different concepts. Mean temperature differences pertain to the average temperature gradient within a system. Enthalpy is the total heat content of a substance and includes both internal energy and the energy associated with pressure and volume, rather than a specific phase change context. MBH refers to a measure of heat transfer, specifically in terms of thousands of BTUs per hour, and does not specifically deal with the change of state like latent heat does.

Understanding latent heat is essential for anyone involved in HVAC systems