Performance study of SAPO-34 and FAPO-34 desiccants for desiccant coated heat exchanger systems

• SAPO-34 and FAPO-34 coated sheets were prepared for desiccant coated heat exchanger.
• SAPO-34 and FAPO-34 coated sheets had better sorption capacity than silica gel.
• Performance curves of both desiccant coatings were divided into three sections.
• FAPO-34 can be a promising desiccant in a desiccant coated heat exchanger system.

A DCHE (desiccant coated heat exchanger) is a novel solid desiccant component with desiccant coated onto the surface of a fin-tube heat exchanger, in which desiccant coated aluminum-fin is an important part. It has an impact on overall performance of the whole desiccant cooling system. In this study, different zeolite-like powders (SAPO-34 and FAPO-34) coated aluminum sheets were fabricated. Their performance was tested and analyzed to investigate the feasibility in a DCHE system. Experimental values of surface area and pore parameters for desiccant coatings had a slight reduction because of the existence of binder solution. Adsorption kinetics indicated that the binder solution would not affect water adsorption capacity or adsorption kinetics of original desiccant powder. Moreover, SAPO-34 and FAPO-34 coated aluminum sheets had higher adsorption capacity than that of silica gel. Sorption isotherms were also measured and fitting equations were developed based on Polanyi principle. Finally, their dehumidification performance in DCHE systems was predicted with a mathematical model. Simulation results indicated that the DCHE prepared from FAPO-34 can have 2–3 times larger dehumidification capacity than those from SAPO-34 and silica gel at low regeneration temperatures.