Preparation and properties of phase change temperature-tuned composite phase change material based on sodium acetate trihydrate–urea/fumed silica for radiant floor heating system

In this work, a novel phase change temperature-tuned composite phase change material (PCM) for the PCM floor was developed by using sodium acetate trihydrate-urea non-eutectic mixture as PCM and fumed silica (SiO2) as both supporting material and temperature regulator. The thermoregulation mechanism of SiO2 and the properties of the resulting composite PCM were studied. The results showed that the addition of SiO2 could adjust melting temperature of the non-eutectic mixture from 34.36 to 48.45 °C, reduce supercooling degree and prevent leakage. With SiO2 mass fraction of 30%, the composite PCM had a suitable melting temperature (35.75 °C), high latent heat (151.6 kJ·kg−1) and low supercooling degree (1.14 °C). Meanwhile, the composite PCM possessed a good form stability and excellent thermal reliability and favorable thermal conductivity. Considering the above, the novel composite PCM has a great potential for the PCM floor. It is also expected that the present work can provide a new insight into tailoring phase change temperature of PCMs.