Methods of increasing humidity

In order to obtain a high rate of humidification, the area of contact between the air and the watet is made as large as possible by supplying the water in the form of a fine spray alternatively, the interfacial area is increased by using a packed column. Evaporation occurs if the humidity at the surface is greater than that in the bulk of the air that is. if the temperature of the water is above the dew point of the air. 

When humidification is carried out in a packed column, the water which is not ev aporated can be recirculated so as to reduce the requirements of fresh water. As a result of continued recirculation, the temperature of the water will approach the adiabatic saturation temperature of the air, and the air leaving the column will be cooled — in sotne cases to within 1 deg K of the temperature of the water. If the temperature of the air is lo be maintained constant, or raised, the water must be heated. 

Since complete humidification is not always attained, an allowance must be made when designing air humidification cycles. For example, if only 95 per cent saturation is attained the adiabatic cooling line should be followed only to the point corresponding to that degree of saturation, and therefore the gas must be heated to a slightly higher temperature before adiabatic cooling is commenced. 

Air at 3(X) K and 20 per cent humidity is to be heated in two stages with intermediate saturation with water to 90 per cent humidity so that the final stream is at 320 K and 20 per cent humidity. What is the humidity of the exit stream and the conditions at the end of each stage  

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The use of direct steam injection into air is a common method of increasing humidity levels for both commercial and industrial applications. The process kills most types of bacteria and similar organisms that may contribute to fouling, health, or other indoor air quality (IAQ) problems. Where amines are present in the steam, however, even small concentrations can be detected by their odor and may be objectionable, even though they may be well under guidelines for concentrations in air. 

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