Polymer/alumina composite desiccant combined with periodic total heat exchangers for air-conditioning systems

• We experimentally investigate a composite desiccant periodic total heat exchanger.
• The device does not need additional energy consumption of rotary mechanism.
• Silica gel packed bed regenerating at 40°C reduces humidity ratio by 2.1 g/kg.
• Active alumina packed bed regenerating at 25°C reduces humidity ratio by 1.7 g/kg.
• Power consumption of composite desiccant system is 33% lower than packed bed system.

The periodic total heat exchanger system consists of four centrifugal fans and two desiccant beds. During the half-period, one fan drives air through one desiccant bed for adsorption and the other fan operating in the opposite direction induces air through the other desiccant bed for desorption. In the next half-period, both air-flow directions are reversed by the other two fans. In this work, periodic operations are tested under different regeneration temperatures (40°C and 25°C), along with six different desiccant beds: silica gel, polyacrylic acid, activated alumina, a molecular sieve, diatomite and a polymer/alumina composite. A silica gel-packed bed provides an alternative to high-cost honeycomb silica gel in 40°C regeneration temperature systems. Alumina shows comparable performance to honeycomb silica gel and has further cost advantages in low regeneration systems. The power consumption of low pressure drop composite desiccant systems shows an improvement of 33% over packed bed systems.