A new approach for efficient dehumidification

Dehumidification of air is an important economic activity responsible for high primary energy use. Several technologies are available that lower both, cost and primary energy use, such as heat pump dehumidification systems, desiccant dehumidification wheels, or other absorption systems. However, the drying efficiency of these technologies is still far below the expected efficiency as prospected by thermodynamic analyses based on the second law. This paper looks into the thermodynamics of drying and proposes a novel dehumidification technology. The proposed system consists of a heat mass exchanger and a mechanical vapour compression unit and is called a vapour heat pump. First, humid air is brought in contact with a hygroscopic salt solution in the exchanger unit and second, the diluted salt solution is reconcentrated by the mechanical vapour compression unit. An analysis of the vapour heat pump indicates a dehumidification efficiency of 6.6 to 9.3. A successful development of the vapour heat pump can have an important effect on the worldwide energy use and sustainability.