**3. System description**

The cooling needs for thermal comfort and sunshine timings follow the same pattern. The demand of air conditioning is higher in summer when the sun shines with higher intensity. What if this intensity of sun can be used as an input energy source for the cooling devices?

should be conducted on innovative design of this technology taking into consideration the associated investment costs. The development of technology is in progress and it is attaining stability in the market. It appears to be reliable, safe, and environmental friendly system according to the needs of our society. This technology needs to be developed and more atten-

Renewable and Sustainable Air Conditioning http://dx.doi.org/10.5772/intechopen.73166 127

Desiccant cooling is used as an alternative to conventional cooling system. These systems operate without the use of any refrigerant and control the latent as well as sensible load independently which helps in better control of moisture and improve air quality. Thermal energy required for regeneration of these units can be supplied from different heat sources such as

Desiccant technology is a cooling technology which removes moisture from air by a process known as sorption (adsorption or absorption). Different desiccant materials are used for this process. Due to vapor pressure difference, adsorption material absorbs the water vapors from the air. To repeat the cycle continuously, moisture from the desiccant wheel is removed using thermal energy. Basic operating cycles of solid and liquid desiccant cooling are illustrated in **Figure 7** [12] and **Figure 8** [13], respectively. In both cooling systems, desiccant dehumidifier is the major component which controls the latent load followed by an addition cooing system i.e. evaporative cooler. Input heat is provided through some thermal energy medium

**Figure 7.** (a) Systematic solid desiccant cooling system with evaporative cooler (b) psychometric processes [12].

tion is required for its implementation and promotion.

**4. Desiccant cooling cycles**

solar, biomass, waste heat, etc.

The issues related to conventional air conditioning technology can be addressed using a new technology called desiccant-based evaporative cooling. This technology is a combination of a desiccant dehumidifier and an evaporative cooler. The schematic representation of desiccant cooling system is shown in **Figure 6** [1]. In such systems, the energy is required to drive the fans, operate the water pump, and to regenerate the desiccant dehumidifier. The required energy can be provided using solar thermal collector for desiccant dehumidifier and photovoltaic modules to drive the fans and the water pump according to the load requirements. The desiccant dehumidifier controls the latent load whereas; evaporative cooler controls the sensible load. Heat recovery medium is used to make the system more energy efficient. For the continuous operation of the system, the regeneration air is heated up to the required regeneration temperature using a solar thermal collector to regenerate the desiccant dehumidifier. The load demand and sunshine follows the same profile which makes this system an effective alternative to conventional air conditioning system. The energy demands for continuous operation of this system can be fulfilled using solar heat according to the load profile.

The use of desiccant cooling technology reduces the energy consumption substantially because of no overcooling and reheating of supply air for moisture removal. More research

**Figure 6.** Principle of desiccant-based evaporative cooling technology [1].

should be conducted on innovative design of this technology taking into consideration the associated investment costs. The development of technology is in progress and it is attaining stability in the market. It appears to be reliable, safe, and environmental friendly system according to the needs of our society. This technology needs to be developed and more attention is required for its implementation and promotion.
