Synergistic hygrothermal regulation of atmospheric-synthesized iron-based metal-organic framework and microencapsulated phase change material composites: Optimization and scale-model validation

Passive hygrothermal regulation is a key strategy for reducing substantial energy consumption of building HVAC systems, yet current materials face thermodynamic limitations, primarily due to the release of adsorption heat during moisture capture leads to local temperature spikes that suppress moisture uptake efficiency. This study addresses this challenge by developing a novel dual-functional composite integrating the iron-based metal-organic framework (MOF), MIL-100(Fe), with microencapsulated phase change materials (MPCMs). Unlike conventional hydrothermal methods, we employed a facile, fluoride-free atmospheric pressure synthesis strategy at 95 °C to fabricate MIL-100(Fe), significantly enhancing engineering scalability and reducing energy input and equipment costs. Structural characterization (XRD, SEM) confirmed that the physical blending process preserved the porous MOF framework and the structural integrity of the MPCM shell. We propose a synergistic ‘in-situ thermal management’ mechanism, where the phase change latent heat of the MPCMs effectively absorbs the adsorption heat released by the MOF, providing a locally buffered thermal environment that mitigates temperature-induced efficiency decay and extends moisture buffering capacity. Through dynamic sorption testing and optimization, a composition of 50 wt% MPCM was identified as the optimal balance for high-humidity climates. Validation in 1:10 scale physical model rooms under dynamic weather conditions demonstrated that the composite reduced peak indoor temperatures by up to 1.44 °C under dynamic climatic cycling and 0.9 °C under controlled heating load, achieving a temperature fluctuation decrement factor (f) of 0.71 and a time lag of 0.33 h, and significantly suppressed relative humidity fluctuations compared to the comparison space. These findings provide a viable engineering reference for passive building energy conservation, bridging the gap between material synthesis and practical engineering application.