Condensation retardation performance of metal-organic framework-based composite humidity-control materials in a radiation cooling room

Abstract

The use of radiant cooling systems in humid regions is limited by surface condensation. Promising advancements have been made in the field of humidity regulation through the utilization of novel high-capacity adsorption materials, known as porous metal-organic frameworks (MOF), which possess expansive surface areas. This study investigated the condensation retardation performance of MOF-based composite humidity-control materials used as surface coatings in a typical radiation cooling room. A total of 16 working conditions in summer were tested, including extreme and typical climates, open windows, and fresh air supply. The influence of two types of MOF-based coating materials and two types of ceiling constructions (with or without a desiccant interlayer) on humidity was analyzed. The results showed that the coating materials and desiccant interlayer construction significantly affected condensation retardation and indoor humidity ratio variation. The better the moisture regulation performance of the material, the lower the risk of condensation. Under extremely high-humidity conditions, the MOF-based coating delayed the critical condensation time by up to 4.5 times that under no-coating conditions. The risk of condensation decreased with improvement of ideal Moisture Buffer Value (MBVideal) of the material, and with the addition of desiccant interlayer during ceiling construction. A coating material with a higher MBVideal can increase the average values of the difference between the surface and dew point temperatures by as much as 181.0%, compared with an uncoated ceiling. The average difference between the surface and dew point temperatures was found to increase by up to 2.11 °C, compared with that for the desiccant-free construction.