Experimental investigation on a low dew point dehumidification system with temperature and pressure swing adsorption using desiccant coated heat exchanger

Abstract

The supply of low-humidity dry air with a dew point below −30 °C mainly relies on desiccant wheels (DW) and adsorption towers (AT), while the high regeneration temperature and adsorption pressure result in substantial energy consumption. This study proposes a low dew point dehumidification system with temperature and pressure swing adsorption (TPSA) using desiccant coated heat exchangers (DCHE). The energy efficiency is improved since the highest temperature and pressure are lowered compared with DW and AT. An experimental setup is designed to evaluate the system dehumidification and energy performance. Experiments under multiple operation conditions are conducted for parametric analysis and operation strategy optimization. Results indicate that the mean outlet dew point is −36.99 °C while the minimum reaches −58.18 °C at the regeneration temperature of 80 °C and adsorption pressure of 180 kPa. The system can save more than 42% of specific energy consumption and the system efficiency is 28% higher compared with DW and AT. Dew point can be lower under higher adsorption pressure and longer cycle time. Extending dehumidification duration and delaying the switch time are conducive to higher comprehensive performance. The mean outlet dew point can be lower than −45 °C with over 78% increase in system efficiency compared with baseline condition at the optimal configuration of 960 s dehumidification + 480 s regeneration with a delay time of 40 s or 60 s.