Synthesis and Temperature Control Performance of Silica Gel Waste Composite Phase Change Materials

In this study, silica gel waste(SGW) was utilized to prepare porous silicon dioxide(PSD) as a carrier, combined with capric acid-hexadecyl alcohol(DA-HD) as the base phase change material(PCM), to develop the composite PCM capric acid-hexadecyl alcohol/porous silicon dioxide(PSD-DA-HD). Expanded graphite(EG) was introduced to enhance the thermal conductivity of the material. The thermal performance of the composite PCM was evaluated using differential scanning calorimetry(DSC), thermogravimetric analysis(TGA), and thermal constant analysis. The composite PCM was then blended with cement mortar to form phase change mortar, and its temperature regulation capability was studied in simulated application experiments. The results indicate that DA-HD is physically encapsulated within the pores of PSD, achieving a loading capacity of 61.7%, with an enthalpy value of 105.6 J/g. The PSD-DA-HD composite PCM demonstrates good shape stability. The introduction of expanded graphite increased the thermal conductivity of the PSD/EG-DA-HD composite PCM to 0.9513 W<middle dot>m-1<middle dot>K-1 but reduced its loading capacity to 49.5%, with an enthalpy value of 88.1 J/g. Both PSD-DA-HD and PSD/EG-DA-HD exhibit a maximum working temperature of 92.2 degrees C, ensuring thermal stability below this threshold. When PSD-DA-HD and PSD/EG-DA-HD were mixed with cement mortar, the resulting phase change mortars displayed excellent heat storage and temperature regulation properties. The phase change mortars C-PSD-DA-HD and C-PSD/EG-DA-HD maintained stable temperatures for 12.7 and 6.7 min, respectively, within the temperature range of 18-32 degrees C. In the simulation experiments, the phase change mortar containing PSD-DA-HD extended the temperature regulation duration by 267.92% compared to the control group without PCMs in the same temperature range.