Dehumidifiers
Equipment designed to reduce the amount of water vapor in the atmosphere.
A system employing the use of cooling for dehumidifying consists of a circulating fan and cooling coil. The cooling coil may use cold water obtained from wells or a refrigeration plant, or may be a direct-expansion refrigeration coil. In place of a coil, a spray washer may be used in which the air passes through two or more banks of sprays of cold water or brine, depending upon the dew-point temperature required.
Dehumidifying by compression and aftercooling is used when the reduction of water vapor in a compressed-air system is required. This is particularly important, for example, if the air is used for automatic control instruments or cleaning of delicate machined parts. The power required for compression systems is so high compared to power requirements for dehumidifying by either the sorbent or refrigeration method that the compression system is not an economical one if dehumidifying is the only end result required.
Mechanical/refrigerative dehumidifiers usually work by drawing moist air over a refrigerated coil with a small fan. Since the saturation vapor pressure of water decreases with decreasing temperature, the water in the air condenses, and drips into a collecting bucket. The air is then reheated by the warmer side of the refrigeration coil.
Most dehumidifiers can be adapted to connect the drip output directly to a drain. Manufacturers may price dehumidifiers differently solely on the size of the collection bucket. There are usually sensors to detect when the collection bucket is full.
