Experimental and modeling study of bubble absorption-based deep dehumidification using the ionic liquid: Parametric analysis on heat and mass transfer

Abstract

Conventional liquid desiccant dehumidification is good at humidity control with energy conservation and stable operation, but is limited by corrosion and crystallization in deep dehumidification. Thus, it is necessary to broaden the humidity adjustment range of liquid desiccant deep dehumidification as well as avoid corrosion. Ionic liquids (ILs) with deep dehumidification potential (e.g., extremely low vapor pressure and non-corrosion) are a promising alternative to traditional salt solutions. Meanwhile, the bubble absorption-based mode can obtain a huge gas–liquid specific interfacial area, which is expected to solve the low wettability and insufficient gas–liquid transfer efficiency in traditional falling-film/packed dehumidifiers using IL. In this work, the bubble absorption-based deep dehumidification using IL (BADD-IL) is investigated. Meanwhile, the heat and mass transfer mathematical model of BADD-IL is established, and a bubble column dehumidifier using the novel IL is experimentally examined under different conditions. The results indicated that the deep dehumidification performance is strongly dependent on operating parameters, and the minimum outlet air humidity ratio is around 1.2 g/kgda. In particular, it is most sensitive to inlet air humidity ratio, followed by liquid height and superficial velocity, and the effect of solution temperature is the least. Notably, the influential mechanism of superficial velocity and solution temperature on volumetric transfer coefficient is different. The increase of superficial velocity promotes both gas–liquid specific interfacial area and heat and mass transfer coefficient. For the IL with lower temperature, its higher heat and mass transfer coefficient makes up for the poor specific interfacial area caused by high viscosity. Additionally, the Lewis factor of bubble column dehumidifier using the novel IL is basically less than 0.6, which is important for the device design and scale-up. This study clarifies the heat and mass transfer mechanism of BADD-IL, and provides guidance for the development of ILs deep dehumidification technology.