The process of humidification occurs when a gas stream is brought in contact with a liquid stream (typically water). Liquid evaporates at the gas-liquid interface and the liquid vapor humidifies the gas. Conventionally, Spray or Bubble columns have been used for humidification. However, Liqui-Cel® Membrane Contactors offer a more efficient method.

A membrane contactor is made from microporous hydrophobic hollow fiber membranes, which repel water and allow stable gas-liquid interface to form without dispersion. If the liquid is water or an aqueous solution the membrane pores remain gas-filled and the rate of humidification is controlled only by diffusion in the gas phase, which is very fast. If the membrane does not repel the liquid and the pores are filled by wicking action, membrane contactors will still work under appropriate process conditions. Humidification with a liquid other than water (e.g. an organic solvent) is therefore also possible.