Background

Vapor Compression

The most common method of dehumidification is the vapor compression model where incoming air is cooled down to the dew point by refrigerant flowing through metal coils. When the air comes in contact with the coils, the water vapor in the air condenses on the exterior of the coils, similar to condensation occurring on a glass of iced tea during a hot, summer day. The air is then reheated to the desired temperature before being exhausted into the living environment.

Though this technology is currently the status quo, it has not changed since its invention in 1902 and still exhibits a number of different problems.

  • Wastes between 20-35% of the energy because it requires cooling below the comfort level and then reheating
  • Inefficient to use in environments where high humidity is of concern
  • Choice between air being too cold (comfortable humidity) or air being too humid (comfortable temperature)
  • Risk of bacterial contamination due to stagnant water on the coils

Desiccant

There have been some attempts at changing temperature and humidity separately. Desiccants, both liquid and solid, have been used to dehumidify independently of temperature. These are very efficient in removing liquid from the air; however, they require excessive energy to regenerate themselves, often an amount that exceeds reject condenser heat from the air conditioning system. The desiccant wheel has become the standard in solid desiccant dehumidification. This technology, though innovative, also requires that the air streams be relatively clean to prevent ‘clogging’ the desiccant itself and is subject to frequent maintenance and repair. This alone makes it impractical in environments where maintenance is difficult.

Some have started to do research on liquid desiccants, which offer the same benefits as their solid counterparts. However, these have been largely discounted because of the danger they impose. Because the air stream is in direct contact with the liquid desiccant, contamination is common and poses a major inhalation problem.

Osmotic Membrane Dehumidification

Osmotic dehumidification offers a new method of dehumidification far superior to anything previously invented. By combining two known processes, capillary action and osmosis, we can achieve humidity as low as 50% RH using energy supplied by a simple fan already included in the traditional air conditioner. This process is further described here.

Many of the problems found with desiccant dehumidification and vapor compression dehumidification are eliminated using our novel method.

  • Temperature and humidity can be controlled independently – often dehumidification is more than enough to make a room comfortable without air conditioning
  • No stagnant water means no risk of bacterial contamination
  • Few moving parts eliminating the risk of frequent maintenance
  • Reject heat, required only when available, is used to regenerate salt solution
  • No risk of contaminating air stream with liquid desiccant