Development of diatomite-based shape-stabilized composite phase change material for use in floor radiant heating

• Diatomite calcined at 400 °C had high porosity, large specific surface area and clear pore structure. • SAT-AC-AlN CPCM was stabilized by Diatomite-400 through physical forces. • Diatomite-based SSCPCM melted at 46.5 °C with latent heat of 162.5 kJ/kg and supercooling degree of 0.33 °C. • Diatomite-based SSCPCM exhibited a good thermal stability and thermal reliability. The utilization of phase change materials (PCMs) in floor radiant heating system can reduce energy consumption along with enhancing thermal comfort by reducing indoor temperature fluctuations. However, the leakage and poor thermal performance of PCM limit its further applications. Here, to solve the above problems, sodium acetate trihydrate (SAT)-acetamide (AC)-micron/nano aluminum nitride (AlN) composite phase change material (CPCM) was composited with heat-treated diatomite to prepare diatomite-based shape-stabilized CPCM (SSCPCM) for use in floor radiant heating. The effect of treating temperature on diatomite’s porous structure was analyzed by porosity analyzer to determine the optimal heat-treated diatomite as supporting material. Subsequently, the effects of the mass fraction of diatomite on phase change properties, and shape-stabilized ability of diatomite-based SSCPCM were investigated. Meanwhile, the morphology, chemical compatibility analysis and thermal properties of SSCPCM were discussed in detail. Results indicated that diatomite calcined at 400 °C had large surface area and high porosity, giving it good adsorptive capacity for SAT-AC-AlN CPCM. SSCPCM with 37.5 wt% diatomite had a good shape stability, which melted at 46.5 °C with high latent heat of 162.5 kJ/kg, low supercooling degree of 0.33 °C and good thermal stability and thermal reliability, making it prospective potential in floor radiant heating.