A humidifier is a piece of equipment that mixes two components together in the gas phase. Generally humidifiers are used to add liquid water to a gas phase stream, but any liquid may be used. The liquid is converted to a vapor either by the introduction of heat or convective forces from the gas phase stream. This produces process often produces a supersaturated gas stream with residual liquid vapor in the stream. Devices like steam traps may be used after a humidification process to capture and recycle excess vapor and insure a dry gas stream.
A basic schematic of a humidifier is shown below:
One liquid and one gas phase enter the humidifier. A fan may induce rapid flow
of the gas across the surface of the liquid, or alternatively the liquid may be brought
to a rapid boil, producing liquid vapor. The combined streams then exit the humidifier.