Moisture uptake dynamics on desiccant-coated, water-sorbing heat exchanger

• Published in: International journal of thermal sciences Vol. 126; pp. 13 - 22
• Main Authors: Tu, Y.D., Wang, R.Z., Ge, T.S.
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 01.04.2018
• Subjects: Desiccant coated layer; Linear driving force model; Parametric estimation; Water-sorbing heat exchanger; Desiccant coated layer; Water-sorbing heat exchanger; Linear driving force model; Parametric estimation
• ISSN: 1290-0729; 1778-4166
• DOI: 10.1016/j.ijthermalsci.2017.12.015

Recently a novel concept of water-sorbing heat exchanger has been proposed, which can independently handle latent and sensible loads at the same time and provide a very promising high-efficient solution for temperature and humidity control. Obviously, moisture uptake behavior has great influence on heat exchanger's performance. Here, a series of experiments have been made to clarify whether the linear driving force (LDF) model could be used to describe this behavior and to investigate the water uptake mode at different times. Results show that the LDF model is valid for water-sorbing heat exchanger and the moisture uptake experiences four different modes in general, including non-isothermal adsorption, near-isothermal adsorption, capillary condensation and cooling-based condensation. This study also confirms that salts in porous matrix can accelerate moisture uptake and promote capillary condensation. These results in a great improvement of dehumidification capacity. Besides, an empirical and a semi-empirical framework were developed to evaluate the constant parameters in the LDF model. Meanwhile, a figure of merit of the desiccant, Z, was defined for engineering application, to simplify the LDF model in further. •This is the first time to experimentally confirm the reliability of the LDF model for open system under real conditions.•There are four water uptake modes for desiccant-coated, water-sorbing heat exchanger.•Capillary condensation is dominating under air-conditioning conditions, instead of adsorption.•The proposed methods of parametric estimation make the LDF model available for heat exchanger designers and researchers.