Abstract

Thermal energy storage (TES) is an expanding field which aim is to assist in the implementation of the renewable energies technologies and to improve the energy efficiency in well-known and established processes by recovering and storing heat. The main properties for TES materials are density, specific heat capacity, latent heat in phase change materials (PCM’s), thermal conductivity and cycling stability, as well as availability and costs. One of the main problems found in the literature is the low thermal conductivity of the materials slows down the charge/discharge process. Therefore, recently it has been introduced highly conductive nanometer-sized (1-100 nm) nanostructures (nanoparticles, nanotubes, nanofibers, etc.) into TES materials forming nanostructured composites in order to improve the thermal properties. It has been reported the improvement in thermal properties such specific heat capacity and thermal conductivity in heat transfer and thermal energy storage materials. In this work it has been studied the effect of nanoparticles in molten salt based composite for high temperature TES material to study the enhancement of its thermal properties. Different amounts of SiO2 nanoparticles have been added to the salt mixture. The main properties for TES application versus nanoparticles content in the molten salt has been characterized such as density, thermal conductivity, melting point and specific heat capacity showing an increase of the thermal conductivity of the composite that leads to a reduction of the cost of the power when the composites are incorporated in TES, Concentrated Solar Power (CSP) or Heat Transfer Fluid (HTF) applications.