Desiccant materials play a key role on the dehumidification performance of desiccant coated heat exchanger (DCHE). The equilibrium water adsorption capacity and adsorption kinetics of Na+ and K+ modified polyacrylic acid salts were tested using an improved gas adsorption analyzer (ASAP 2020) and a constant temperature humidity chamber

with conventional silica gel as reference. Researches on equilibrium adsorption show that

Na+ modified polyacrylic acid salt had a water uptake much higher than that of silica gel

while the K+ modified one was inferior to silica gel at a relative humidity range higher than 0.8. Besides

sorption characteristic curves were fitted based on the Polanyi potential theory and can be used in simulating dehumidification performance. Adsorption kinetics tests displayed that the rate coefficients of both ions modified by polyacrylic acid salts were lower than that of silica gel; however

the dynamic water adsorption quantities of the Na+ modified one during an adsorption process of three hours were still higher than those of silica gel. Finally

the dehumidification performance of the Na+ modified polyacrylic acid salt was evaluated and compared to silica gel using a validated mathematical model of the DCHE system

with water as a refrigerant under three different ambient air conditions

i.e. ARI summer

ARI humid

and Shanghai summer. Simulation results suggested that the modified Na+ could remove 49%–118% more moisture from the process air and possessed greater superiority especially for conditions with lower atmospheric humidity.