Efforts to improve energy efficiency in buildings by tightening building envelopes and improving thermal insulation do not address indoor air quality (IAQ) issues or the issue of latent (moisture-related) cooling loads in buildings. Conventional air conditioners are not designed to handle the large ventilation rates needed to provide acceptable IAQ or overcome moisture buildup. The effects of the "sick building syndrome" on public health and productivity and of moisture damage are major incentives to develop energy-efficient space conditioning systems that provide high levels of humidity control.
Desiccants can improve the indoor air quality of all types of buildings. Desiccant cooling systems can be used as stand-alone systems or with conventional air-conditioning. In these systems, a desiccant removes moisture from the air, which releases heat and increases the air temperature. The dry air is cooled using either evaporative cooling or the cooling coils of a conventional air conditioner. The absorbed moisture in the desiccant is then removed (the desiccant is regenerated, or brought back to its original dry state) using thermal energy supplied by natural gas, electricity, waste heat, or the sun. Commercially available desiccants include silica gel, activated alumina, natural and synthetic zeolites, lithium chloride, and synthetic polymers.
Desiccant systems can supplement conventional air conditioners, reducing the need for vapor-compression systems to operate for long cycles and at low temperatures in order to handle temperature and humidity. By working together, conventional cooling systems and desiccant systems can tackle the temperature and humidity loads separately and more efficiently. Heating, ventilating, and air conditioning engineers can then reduce compressor size and eliminate excess chiller capacity.
Desiccant technologies have numerous current and potential applications. For example:
Currently, KING-DESICCANT® is conducting desiccant research and development in the following areas: