Synthesis and characterization of multifunctional energy composite: Solar absorber and latent heat storage material of high thermal conductivity

•PCM and graphite composites have been elaborated for different solar applications.•Storage capacity, conductivities and absorbance measurements have been performed.•According to the solar spectra, composites present high absorbance (>0.9).•Directional reflectance measurements highlight composites specular behavior.

Phase change materials (PCM) used in thermal energy storage systems present high storage capacity and require low temperature variation to allow effective heat charge or discharge density. However, these materials involve too low thermal conductivities (<1 W m−1 K−1) which can limit the heat transfer power between the heat transfer fluid and the phase change zone. In the first part of this study, high power level composites made of PCM (organic and also inorganic) and graphite have been elaborated in the thermal range from 50 to 350 °C in order to increase the effective thermal conductivity. In a second part, the assessment of their use as solar absorbers has been realized. Results show that these composites present high absorptance with respect to the whole solar radiation spectra. This allows new potentiality of integration of such materials in solar thermal processes offering a direct management of heat variation at the very first step of the process.