چكيده فارسي
Thermal energy storage is one of the most efficient methods to address the energy crisis, and there is a growing demand for improving energy efficiency in buildings. Therefore, concepts such as reducing temperature fluctuations in buildings are being introduced. To meet this need, thermal insulation materials play a crucial role. One of the most effective methods for thermal energy storage applications is the use of phase change materials (PCMs), which absorb a large amount of energy during phase transitions. Several factors must be considered when selecting a PCM, one of which is its phase change temperature, which should be within the range of room temperature to effectively reduce thermal fluctuations in buildings. Additionally, PCMs should have high latent heat, which is essential for storing energy. However, there are limitations—such as low thermal conductivity and leakage of melted PCM—that must be addressed before practical use, as they reduce their applicability in buildings. The aim of this study is to develop a stable PCM (a new phase change material) for thermal energy storage in buildings. For this purpose, a perlite/eutectic mixture of capric acid and myristic acid composite was prepared. Due to its porous structure and thermal insulation properties, perlite serves as a suitable support and host for PCM. By modifying the surface of the perlite and encapsulating the PCM within it, the leakage issue is resolved. Moreover, the addition of 1 wt% silica nanoparticles led to a 20% increase in latent heat and thermal energy storage capacity. Using Differential Scanning Calorimetry (DSC), the latent heat was calculated to be 143.9 J/g. To analyze the stability of the eutectic mixture, Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) were used, while Scanning Electron Microscopy (SEM) was employed to study the microstructure. The maximum impregnation of the nanoparticle-modified eutectic in the perlite improved energy storage performance. However, increasing the PCM mass ratio also increased leakage. Specifically, with 70 wt% impregnation of the nanoparticle-modified eutectic in perlite, leakage reached 90 mm. To solve this problem, a redispersible polymer powder (RDP) was used for surface coating and encapsulation of the nanocomposite. The results show that PCM encapsulation eliminated leakage completely, reducing the leakage diameter to zero. The resulting nanocomposite is thermally stable within its operating temperature range, ensures long-term performance, and effectively reduces indoor temperature fluctuations.
