13 - Review of solar-powered desiccant cooling systems

Abstract

Desiccant cooling systems operate on the principle of adsorption dehumidification and evaporative cooling. Such systems use a natural working fluid and can be driven by low-grade thermal energy, which makes them especially useful for integration with solar collector systems. Because of these merits, solar-powered desiccant cooling systems are widely recognized as good alternatives to conventional vapor compression air-conditioning systems and have attracted increasing interest in the past years. This chapter aims to summarize research developments related to solar-powered rotary desiccant wheel cooling systems and liquid desiccant systems to provide information for potential application. For the solar-powered rotary desiccant wheel cooling system, in the first category, separate solar-powered rotary desiccant wheel cooling systems are reviewed according to the type of solar collector. For the second category, works related to hybrid solar-powered rotary desiccant wheel cooling systems are grouped together by type of auxiliary refrigeration system. We show that the feasibility of separate solar-powered rotary desiccant wheel cooling systems has been validated in representative sites in Europe, Asia, Australia, and Africa. Hybrid solar-powered rotary desiccant wheel cooling systems have a much wider application range because auxiliary cooling power is provided, and the hybrid systems can provide great energy savings compared with the vapor compression systems. As for the solar-powered liquid desiccant systems, they are being used either as stand-alone units or as hybrid units in conjunction with vapor compression systems (VCS) or vapor absorption systems (VAS), the hybrid ones being more in use. In a hybrid system, the desiccant dehumidifier handles the latent cooling load and VCS/VAS handles the sensible cooling load. In addition, the photovoltaic–electrodialysis regeneration method for liquid desiccant cooling systems is also a good choice for some weather conditions. This review is useful for understanding the status quo of solar-powered desiccant cooling systems and highlights future possible improvements.