Silica gel/polymer composite desiccant wheel combined with heat pump for air-conditioning systems

This study focused on using the released heat from a heat pump as the heat source at 40–50 °C to regenerate a silica gel/polymer composite desiccant wheel and also on using the adsorb heat of the heat pump to dehumidify the processed air by condensing it and creating a high relative humidity condition, which helped to improve the performance of the composite desiccant wheel. The desiccant wheel was placed behind the evaporator to handle the second stage of dehumidification, achieving total dehumidification by 7 g kg−1. A new composite desiccant made of 80% silica gel, 10% polyacrylic acid and 10% polyacrylic sodium (SG8PS1PA1) was chosen due to its high average adsorption rate and its low average temperature increase of outlet air. Composite desiccants can be made into any shape, so a low-pressure-drop composite desiccant wheel with air flow channels can be designed to reduce the power consumption of the system. Under the same conditions, a composite desiccant in a heat pump system exhibited an energy factor of 2.3 kg kW−1 h−1, outperforming the silica-gel-based system by 130% and consuming less power than traditional dehumidification systems. Finally, the composite desiccant wheel-heat pump system was installed in a building and underwent long-term testing.