Dehumidifier

Dehumidification is the removal of water vapor from air, definition, and sorption dehumidification equipment has been designed and operated successfully for system pressures ranging from subatmospheric to as high as 6000 psi. The term dehumidification is normally limited to equipment that operates at essentially atmospheric pressures and is built to standards similar to other types of air-handling equipment. For drying gases under pressure, or liquids, the term dryer or dehydrator is normally used.

Nothing turns a hot day more oppressive than high humidity. In rooms that don't really merit an air conditioner, or to cut down on the use of an air conditioner, simply run a dehumidifier to make living more bearable.

The recommended humidity level inside your home during the summer is around 40 to 50 percent, and high indoor humidity can make you uncomfortable and adversely affect your home. Musty smells, peeling wallpaper, warped wood, blistering paint and moisture dripping from water pipes indicate excessive humidity and the need for a dehumidifier.

Dehumidifiers remove excess humidity by drawing moist room air over cold refrigerated coils. The moisture in the air condenses into droplets as it passes over the cold surfaces in the dehumidifier and into a container. "Dried" air then returns to the room at approximately its original temperature.

Some commercial applications of dehumidification include

• Lowering relative humidity to facilitate manufacturing and handling of hygroscopic materials
• Lowering the dew point to prevent condensation on products manufactured in low-temperature processes
• Providing protective atmospheres for the heat treatment of metals
• Controlling humidity in warehouses and caves used for storage
• Preserving ships, aircraft, and industrial equipment that would otherwise deteriorate
• Maintaining a dry atmosphere in a closed space or container, such as the cargo hold of a ship or numerous static applications
• Eliminating condensation and subsequent corrosion
• Drying air to speed the drying of heat-sensitive products, such as candy, seeds, and photographic film
• Drying natural gas
• Drying gases that are to be liquefied
• Drying instrument air and plant air
• Drying process and industrial gases
• Dehydration of liquids
• Frost-free cooling for low-temperature process areas such as
brewery fermenting, aging, filtering, and storage cellars; blast
freezers; and refrigerated warehouses
• Frost-free dehumidification for processes that require air at a subfreezing dew point humidity

Methods of dehumidifications

Cooling

Refrigeration of the air below its dew point is the most common method of dehumidification. This method is advantageous when the gas is comparatively warm, has a high moisture content, and when the outlet dew point desired is above 40°F. Frequently, refrigeration is used in combination with desiccant dehumidifiers to obtain an extremely low dew point at minimum cost.

Liquid Desiccant

Liquid desiccant conditioners (absorbers) contact the air with a liquid desiccant, such as lithium chloride or glycol solution . The water vapor pressure of the solution is a function of its temperature and its concentration. Higher concentrations and lower temperatures result in lower water vapor pressures.