Lauric acid/stearic acid/nano-particles composite phase change materials for energy storage in buildings

Abstract

Composite organic phase change materials (PCMs) have gained wide applications in buildings due to their superior latent heat capacity, stable properties, and most notably, the ability to adjust their melting temperatures as required. In this study, lauric acid (LA) and stearic acid (SA) were selected as the matrix of PCM, which is used to store and release thermal energy. The step-cooling curve method was utilized to test and draw the binary equilibrium phase diagram of the two materials. The composite PCM achieved its lowest eutectic temperature of 31.2 °C when the weight ratio of LA/SA was 7:3, demonstrating suitability for building envelopes. To enhance the thermal conductivity of the composite PCM, nano‑copper oxide (nano-CuO) and nano‑silicon dioxide (nano-SiO2) were added into the composite PCM as thermal conductivity enhancing materials. The study compared the effects of different dispersants, different nanoparticle to dispersant ratios, and nanoparticle concentrations on the stability and uniformity of the experimental materials. The thermal properties were analyzed using Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), thermal conductivity measurement, and thermal absorption and release process analysis. The findings indicate that the 0.2 %nano-CuO/PCM had remarkable stability, with reduced latent heat of melting and solidification by 5.91 % and 5.44 %, respectively, compared to the composite PCM. The thermal conductivity of the material was increased by 30.0 %. This study provides valuable insights for the development of novel nanocomposite PCMs specifically designed for thermal active building wall applications.