Humidification Dehumidification

Introduction to Humidification Dehumidification

Humidification Dehumidification (HDH) is a system of desalination in which a carrier gas is humidified with saline water in one area and dehumidified in another.  The process of humidification leaves the salt behind.  The process of dehumidification condenses out pure water.

How humidification dehumidification works

The HDH system:

  1. Takes a carrier gas
  2. Humidifies it in a humidifier (often a packed bed with a thin film of saline water)
  3. Transfers it to a dehumidifier (often a heat exchanger with the cold feed saline water)
  4. Collects distilled water below the dehumidifier.
  5. Collects brine below the humidifier.

Applications of humidification dehumidification

HDH systems don’t require high-tech membranes or high pressure pumps.  Similarly they are capable of operating at relatively low temperatures and ambient pressure.  As such they can be built from relatively low cost & easily available components.  Certain implementations of HDH can therefore considered an appropriate technology for desalination in developing regions.

HDH systems can also use sunlight as an energy source.  Seawater greenhouses are an example of HDH desalination.