What is the expected temperature change when using an adiabatic humidifier?

• A. The air temperature increases as moisture is added.
• B. The air temperature decreases as moisture is added.
• C. The air temperature remains constant.
• D. The air temperature cycles with humidity.

Answer: (B)

Adiabatic humidification cools the air. When water is added as a fine mist, it evaporates by drawing energy from the surrounding air. Since no external heat is supplied in an adiabatic process, the latent heat needed for evaporation comes from the air itself, causing the sensible temperature to drop. Therefore, as moisture is added, the air temperature decreases. The cooling is typically modest and depends on how much moisture is added and the air’s initial conditions. This is different from humidification methods that add heat (like steam), which would raise the air temperature.