Thermal and mechanical properties of cement based-composite phase change material of butyl stearate/isopropyl palmitate/expanded graphite for low temperature solar thermal applications

Abstract

The thermal storage composite produced in this research was fabricated by integrating a novel eutectic phase change material of 80% butyl stearate (BS) and 20% isopropyl palmitate (ISOP) into supporting material of expanded graphite (EG) without leakage. 10% of eutectic mixture (EM) formed in the form-stable composite EM_EG is incorporated into the cemented test room's south wall in a laboratory-scale. The mass ratio of EM_EG is characterized by leakage test using a filter paper. The EM of BS and ISOP is successfully absorbed into the porous structure of EG, according to scanning electron microscopy (SEM) results. The differential scanning calorimeter (DSC) test demonstrates that the produced form-stable composite has proper phase change temperature of 15–19 °C and latent heat fusion of 119 J/g for thermal management in the buildings. The thermal conductivity is improved with the addition of EG. The thermogravimetric analysis (TGA) test reveals that the prepared novel eutectic and form-stable composite in the low temperature range are thermally stable. Furthermore, the flexural strength and density decreased with the integration of EM_EG. Cone calorimetry is used to investigate the flammability properties of the form-stable composite. In addition, cement containing EM_EG illustrates appreciated thermal performance in reducing the peak indoor temperature. The findings proved that the produced EM_EG composite might be evaluated as a potential material for reducing energy consumption and improving indoor thermal temperature particularly in building envelope.