How does a Dehumidifier work?
Dehumidifiers work on the principle of condensation of water vapour on cold surfaces. Condensation is a common phenomenon in our day-to-day life. For instance, when you fill a glass with cold water, you will notice water particles over the glass surface after sometime. This is because; the air surrounding the glass becomes cool and loses moisture which condenses on the cold surface of glass. In an air conditioner and a dehumidifier, the same principle is used, except these devices use efficient methods for the air to condense with other components for better performance.
Refrigerator, air-conditioner and dehumidifier
All these home appliances use the same technology to cool the air. They use metal coils or fins, fans, pumps and refrigerants. The humid air in the room is drawn using the fan and when the air passes over the coils (which are cold), the excess moisture in the air condenses and the dripping water from the coils is collected in a bucket or removed with a draining system.
However, there is a primary difference between a dehumidifier and an air conditioner. While the air conditioner has only cold coil, the dehumidifier has both cold and hot coils. In a dehumidifier, after the moisture is removed from the air, the air is made to pass over the hot coils and the heated air is returned to the room.
Parts of dehumidifiers
A dehumidifier is an electrical appliance that can use refrigerated coils or desiccant substances for dehumidifying of the air. Most dehumidifiers are of refrigerative type and are suitable for hot places and hot climates. For better performance during winter, these dehumidifiers, the relative humidity of the air needs to be higher than 50 percent.
Dehumidifiers that use desiccant materials are suitable for areas where the temperature is very low and the air has very low humidity levels. They use desiccant susbtances instead of metal coils and they usually require more power than refrigerative type.
A refrigerative type dehumidifier consists of following parts:
- A fan to draw the air from the room.
- A filter that removes dust from the air.
- Cold coils and hot coils
- A bucket or tray to collect the water dripping from the coil.
Dessicant dehumidifers have followng parts:
- A fan to pass the room air over desiccant materials
- Another fan that draws low humid air over desiccant for removing the moisture from it.
- A heater to heat the air
How the air is dehumidified?
A dehumidifier has a fan that draws the air from the room. The dust particles are also filtered and the humid air is passed over the cold coil. The moisture in the air gets condensed at this stage and the excess moisture is removed from the air.
To reset the temperature of the air to the original temperature, the dehumidified air is passed over the heat coil. The dehumidified, heated air is then returned to the room.
As the water drips from cold coil during condensation, a bucket or tray is used to collect it.
How the air is humidified?
Humidification of the air helps it to retain moisture, a process just reversal to dehumidification. During this process, the dry air (which has low relative humidity) is drawn using a fan and passed over a filter that is moistened with cold water.
Depending on the moisture content in the room air, the filter adds moisture to the circulated air. When the high humid air contacts the moistened air, it sucks less moisture while the dry air picks more moisture. This way, the humidification of the air is maintained by the system.
Depending on the moisture content in the room air, the filter adds moisture to the circulated air. When the high humid air contacts the moistened air, it sucks less moisture while the dry air picks more moisture. This way, the humidification of the air is maintained by the system.
