The most common design of humidifiers, also called steam generators. Water vapor in such devices is obtained by heating and evaporation of water, after which, as a rule, the steam force is supplied by a fan or directly in the room or in the ventilation system with the help of steam lines and injectors. The steam generators can be electric and gas. Gas humidifiers are used as an energy source for evaporation of water from natural gas. Typically, they are used where there are difficulties in allocating the necessary for the operation of the steam humidifier electrical power.
In electric steam generators steam is obtained by heating water by electricity. Electric steam humidifiers are divided into steam humidifiers with immersed electrodes and steam humidifiers with heating elements. Steam humidifiers with immersed electrodes heat the water by passing an electric current through it between submerged electrodes. For efficient operation of a humidifier of this type, the water should contain a sufficient amount of dissolved salts that provide the electrical conductivity of water. The steam generator heating elements to evaporate water using one or more electric heating elements and can work even with distilled water. The advantages of steam humidifiers air can be attributed to their relative simplicity, structural reliability, wide operating range. The main disadvantage of humidifiers this type can be considered their high energy requirements for work.
In ultrasound humidifiers water is atomized into tiny droplets by using a high-frequency oscillation and fan received water mist supplied into the space or the ventilation system. Little drops of water surface area is very large relative to the mass of water in the straw, so these drops instantly evaporate in dry air, increasing its humidity. Such humidifiers consume significantly less energy than steam humidifiers. However, their scope is somewhat narrower: ultrasonic humidifiers depend in their work on the parameters of ambient air (high relative humidity reduces the effectiveness of their work).
In addition, the evaporation of large amounts of water requires large amounts of energy. During operation of the humidifier, energy is supplied from an external source (gas or electricity), whilst ultrasonic humidifiers energy is taken from the ambient air, reducing its temperature. Under certain circumstances this can lead to undesirable effects. Furthermore, due to the more complex structures, ultrasonic humidifiers are less undemanding compared to steam humidifiers.