Dehumidifier
From Freepedia
A dehumidifier is a household appliance that reduces the level of humidity in a room.
Mechanical/Refrigerative Dehumidifiers
They usually work by drawing moist air over a refrigerated metal coil with a fan. Since the saturated vapor pressure of water decreases with decreasing temperature (i.e. cold air can hold less water vapor), 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.
Air conditioners automatically act as dehumidifiers when they chill the air and thus need to handle the accumulated water as well. Window units simply allow the water to drip outside. Central air conditioning units need to be connected to a drain.
Desiccant Dehumidifiers
A desiccant dehumidifier is a device that employs a desiccant material to produce a dehumidification affect. Desiccant materials have a high affinity for water vapor. Typically their moisture content is a function of the relative humidity of the surrounding air. Exposed to low relative humidities desiccant materials come to equilibrium at low moisture contents and exposure to high relative humidities results in equilibrium at high moisture contents.A desiccant dehumidifier is a device that employs a desiccant material to produce a dehumidification affect. The process involves exposing the desiccant material to a high relative humidity air stream, allowing it to attract and retain some of the water vapor and then exposing the same desiccants to a lower relative humidity air stream which has the affect of drawing the retained moisture from the desiccant. The first air stream is the air that is being dehumidified while the second air stream is used only to regenerate the desiccant material so that it is ready to begin another cycle. Note that the first air streams water vapor content is reduced while the second air stream's water vapor content is increased. Typically the low relative humidity air stream is air taken from any available source and heated to reduce it's relative humidity. Hence desiccant dehumidifiers consume heat energy to produce a dehumidifying affect.
In general a desiccant dehumidifier is comprised of four major components. The component that holds the desiccant of which there are several types, a fan to move the air to be dehumidified (process air) through the desiccant holder, a fan to move the low humidity air for drying the desiccant through the desiccant holder and a heater to heat the air that will be used to dry the desiccant (regeneration air).
See also humidifier, an appliance that increases the humidity of air.
External links
- Dehumidifying and Drying Air From DoItYourself.com
- Dehumidifiers Guide from About.com
- How Dehumidifiers Work Article by RepairClinic
