Preparation and properties of phase change energy storage composite with microcapsules and desulfurized gypsum

Micro-encapsulated phase change materials (MPCM) was used as energy storage elements and combined with desulfurized gypsum. Effects of MPCM on the mechanical properties, thermal properties and thermal cycle stability of desulfurized gypsum-based composites were investigated. Results show that the latent heat energy storage capacity of MPCM can not only adjust the hydration temperature rise of the slurry, but also gave the composite the power to store energy and regulate temperature. However, the addition of MPCM has a negative effect on the strength of the composite. When the MPCM content is 50wt%, the comprehensive properties of the composite are better. At this time, the phase transition temperature and enthalpy of the composite are 24.51℃ and 28.47 J·g⁻¹, respectively. The temperature peak during heat storage stage and the time to reach the peak temperature are reduced and delayed by 6.4℃ and 980 s, when compared with pure gypsum. The effect of heat storage and temperature control is obvious. The thermal conductivity of the composite is 0.451 W·(m·K)⁻¹ and its 28-day compressive strength is 25.05 MPa. The mass loss rate, phase change temperature change rate and phase change enthalpy change rate of 250 cold hot cycles are 0.67%, 0.08% and 2.3%, respectively, and the thermal cycle stability is good. Phase change energy storage gypsum has good mechanical properties, thermal properties and thermal cycle stability, and has broad application prospects in building envelope structure.