Insights into desiccant-based internally-cooled dehumidification using porous sorbents: From a modeling viewpoint

Abstract

Humidity always accompanies human beings’ life and industry production. A high humidity environment not only induces health hazards easily but also aggravates energy consumption. Desiccant-based internally-cooled dehumidification using porous sorbents represented by desiccant coated heat exchanger (DCHE) is regarded as the high efficient humidity regulation, evoking the overwhelming attention of wider scientific and industrial communities, and booming at different fields in air–water-energy nexus. Although extensive efforts on this manner have been promoted, the depth understanding of heat and mass transfer remains vital. In this review, a comprehensive, clear and full-scale route of DCHE is presented from the thermodynamical viewpoint of modeling. Firstly, the basic principle and heat/mass transfer characteristics of DCHE are restated. Subsequently, model insights of different scales are established including nano-pore, meso-scope coating, macroscopic device and system scale, and the advances in the mathematical methods of DCHE are categorized into thermodynamic, resistance network and discrete element methods. The major derivations, model accuracy and characteristics are detailed, and the diffusivities, adsorption equilibrium equation and heat/mass transfer coefficients are summarized. Furthermore, some attempts for design guidance are reviewed and differences of model on system integration scale are discussed. This review would provide a comprehensive understanding of internally-cooled dehumidification, and pave a pathway for further investigation, design and optimization, as well as DCHE-inspired applications like humidity pump, water harvesting, thermal management, etc.