Humidification is simply the addition of water to air. However, humidity exerts a powerful influence on environmental and physiological factors. Improper humidity levels (either too high or too low) can cause discomfort for people, and can damage many kinds of equipment and materials.
Problems With Dry Air
Dry air can cause a variety of costly, troublesome, and sometimes dangerous problems. Static electricity can accumulate in dry atmospheric conditions and interfere with efficient operation of production machinery or electronic office machines. Where static-prone materials such as paper, films, computer disks, and other plastics are handled, dry air intensely aggravates the static problem. In potentially explosive atmospheres, dry air and its resultant static electricity accumulations can be extremely dangerous.
Humidity and Human Comfort
Studies indicate people are generally most comfortable when relative humidity is maintained between 35% and 55%. When air is dry, moisture evaporates more readily from the skin, producing a feeling of chilliness even with temperatures of 24°C or more.
Isothermal and adiabatic humidification
Two different processes exist and can be set up to increase the percentage of moisture of the air :
In isothermal humidification, water is carried until boiling to be dispersed in the air. This process requires a source of energy however as the mass of the steam is lower than that of the air, the temperature of the air remains stable.
Fogging systems use compressed air to atomize water and create a stream of microscopic water particles which appears as fog. The water particles quickly change from liquid to gas as they absorb heat from the surrounding air. It is a constant enthalpy process and air decreases its temperature. This evaporative cooling can provide energy benefits for systems with high internal heat loads.