Desiccant cooling is an already well-established technology with many commercially available systems. The first systems for this technology were developed in the 1930s by industries that wanted to maintain humidity at low levels. Desiccant cooling can be used in several industrial fields, including the brewing industry, to prevent sanitation problems in cellars, and the pharmaceutical industry, to avoid product contamination (Rafique et al. 2016). They are open cycle systems, using water as the refrigerant, which comes in direct contact with the ambient air. The basic principle of the desiccant cooling cycle consists of a sorption process that takes place to dehumidify the air combined with an evaporative cooling step. In most cases, evaporative cooling is realized by a direct evaporative stage. However, other configurations can also be applied, as will be presented in the section on evaporative cooling (Elsarrag et al. 2016). The sorption material in most cases is a solid desiccant, while several liquid desiccants have been used in experimental setups, as will be discussed further in this chapter. The main drawback of desiccant cooling systems is their low COP in comparison to conventional cooling systems. On the other hand, desiccant cooling cycles have several advantages, including the following:

High energy savings

Avoidance of environmentally harmful fluids by using water as a refrigerant

Desiccants can simultaneously absorb/adsorb harmful substances and particles, thus serving as air filters for an air conditioned room

Operation close to atmospheric pressure

Low maintenance costs