Preparation and characterization of a lauric-myristic-stearic acid/Al2O3-loaded expanded vermiculite composite phase change material with enhanced thermal conductivity

In this study, Al2O3-loaded expanded vermiculite (aEV/AO) with improved adsorption capacity and thermal conductivity was reported as the lauric-myristic-stearic acid eutectic mixture (LA-MA-SA) supporting matrix. The Al2O3-loaded expanded vermiculite was prepared by acid treating expanded vermiculite (aEV) followed by loading Al2O3 particles. The thermal conductivity of LA-MA-SA/aEV/AO was 0.671 W/m K, which was 156.1%, 30.8% and 37.5% higher than that of LA-MA-SA, LA-MA-SA/EV and LA-MA-SA/aEV, respectively. The latent heats of LA-MA-SA/aEV/AO were 113.7 J/g at the melting temperature of 28.6 degrees C and 108.5 J/g at the freezing temperature of 26.9 degrees C, which were also higher than those of LA-MA-SA/EV and LA-MA-SA/aEV. The results of the thermo-gravimetric analysis, thermal cycling test and Fourier transform infrared spectroscopy indicated that the LA-MA-SA/aEV/AO composite PCM was thermally stable and chemically inert. Thus, LA-MA-SA/aEV/AO is a preferential potential thermal energy material for the improving the energy efficiency in building applications due to its proper phase change temperature range, relatively high latent heat and thermal conductivity, good thermal reliability and chemical stability.