Liquid desiccant-based deep dehumidifier working with a novel ionic liquid: Prediction model and performance comparison

Abstract

Deep dehumidification system with energy conservation and stable operation is expected to be used in industrial occasions with low-humidity environment. Compared with solid desiccant dehumidification, liquid desiccant-based dehumidification is a promising alternative because of its advantages of continuous operation and low regeneration temperature. However, corrosion and crystallization problems exist with liquid desiccant-based deep dehumidifier (LDDD) using salt solutions. In this work, LDDD using a novel ionic liquid (IL) was introduced, and the heat and moisture transfer model was established based on the finite difference method. Meanwhile, the moisture transfer characteristics were numerically simulated under different operating parameters (i.e., inlet humidity ratio wa,in, air velocity va, solution mass concentration X, solution temperature ts and solution volume flow Vs). Besides, the significance of various factors and their interactions were analyzed based on response surface methodology. The numerical model is validated against the experiment of the LDDD test bench with a relative deviation of 3%-8%. Numerical results show that the LDDD using IL can achieve deep air dehumidification, and outlet humidity ratio of less than 4 g/kgda is possible. In particular, the order of significance for influencing factors of outlet humidity ratio is: wa,in > X > ts > va > Vs. Moreover, it is found that dehumidification rate of 60% LiBr solution (saturated state) is less than that of 90% IL. This study establishes a prediction model of moisture transfer between IL and air under the coupling of multiple physical fields, and provides guidance for the application of LDDD using ILs.