Effects of thermal conductive fillers on energy storage performance of Form-Stable phase change material integrated in Cement-Based composites

Abstract

• Graphite and nTiO 2 were used to enhance thermal performance of PCM cement composite. • TGA results showed that the PCM composites were thermally stable. • Graphite and nTiO 2 improved the heat transfer rate of PCM composite by 50%. • SEM showed the Graphite and nTiO 2 particles uniformly dispersed in the PCM. • Thermally enhanced PCM composite reduced the peak indoor temperature by 2.5 °C. Energy consumption to achieve thermal comfort in buildings is one of the significant challenges in the construction industry. Hence, applying thermal energy storage (TES) systems, such as phase change material (PCM), is increasingly being considered as a promising solution. However, the low thermal conductivity of PCM has a negative effect on the thermal cycle and, consequently, the efficiency of the TES system. This study aims to develop a novel form-stable PCM cement composite and investigates the effects of two thermal conductive fillers (TCFs), graphite powder and nano titanium dioxide (nTiO 2 ), on the thermal performance of PCM cement composites. For this purpose, the TCFs at different mass fractions (1 and 3 wt%) were dispersed in the PCM using sonication and impregnated into expanded glass aggregates (EGA). The microstructure studies revealed that TCF was well dispersed in the PCM and PCM-TCF was successfully impregnated into the EGA. The results of thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FT-IR) demonstrated that there was no chemical reaction between PCM and TCFs, and the PCM-TCF were thermally stable in the operating temperature ranges. The differential scanning calorimetry (DSC) analysis showed that the latent heat capacity of PCM-TCF remained reasonable with a maximum deduction of 9.6% and supercooling temperature enhancement up to 3.4 °C. The thermal behaviour analysis obtained from infrared thermography (IRT) imaging showed a 50% improvement in the heat transfer rate of the PCM composite. Moreover, a room model experiment revealed that integrating TCFs into PCM significantly enhanced the performance of EGA/PCM cement mortar. This is evidenced by a reduction in peak indoor temperature of up to 2.5 °C compared to the control sample.