Theoretical analysis of a low dew point desiccant dehumidification system with temperature and pressure swing adsorption

Dry air with ultra-low moisture serves as a security condition in numerous industrial and research environments and the supply mainly relies on solid adsorption. However, desiccant wheels (DW) and high-pressure adsorption towers (AT) consume massive energy due to the dependence on high-temperature regeneration and high-pressure adsorption processes. This study proposes a novel low dew point desiccant dehumidification system based on temperature and pressure swing adsorption (TPSA) combined with desiccant coated heat exchangers (DCHE). The system integrates subcooling with desiccant dehumidification in a staged process. Inter-cooled adsorption and elevated pressure overcome the performance limitations under low humidity to provide dry air with dew points lower than −40 °C. Significantly lower regeneration temperature and adsorption pressure lead to a substantial reduction in energy consumption and better energy efficiency can be achieved when combined with renewable energy. Numerical models have been developed to compare the overall performance with other systems. Parametric analysis of various parameters on dehumidification and energy performance is investigated. Results reveal that dry air with a dew point of −40 °C can be obtained at a regeneration temperature of 100 °C and adsorption pressure of 178 kPa, and the energy saving is over 29% compared with AT and DW. The outlet dew point can be as low as −70 °C at 303 kPa, while the system efficiency is 66.7% higher than AT system. The proposed method indicates remarkable improvements in both dehumidification effect and energy efficiency, showing great potential for extensive applications in industrial production and scientific research.