Preparation and characterization of high temperature shape stable NaNO3/diatomite phase change materials with nanoparticles for solar energy storage applications

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• A composite phase change material has been prepared and characterized. • NaNO 3 /diatomite is used as a phase change material at high temperature. • Nano diamond and nano expanded graphite have been added to enhance the thermal conductivity. • The prepared material has 87.32 J/g heating value and solidify at 302.03 °C. • The prepared material can be used as a solar energy storage medium. In this paper, we presented a simple method of preparation, characterization and thermo physical properties of phase change materials with nanoparticles. The study began with the preparation of NaNO 3 /diatomite phase change materials (PCMs) and with adding Nano expanded graphite and Nano diamond additives as a thermal conductivity enhancer for high temperature applications. The composite phase change materials are successfully synthesized using a two-step mixing and sintering method for high temperature applications such as concentrated solar powers and solar reactors. In the following, by using the design of experiment (DOE), two responses (phase change temperature and phase change time stability) were investigated in shape stable composite in phase change materials (SS-CPCM) with and without nanoparticles. DSC and IR-Camera results were used as responses and thermal properties of the SS-CPCM. Economical SS-CPCM was prepared, characterized, and optimized by DOE software. Experimental analysis, including 20 runs, has been taken using a design of experiment, and the optimum run has been selected. The optimum SS-CPCM has a latent heat of 87.32 J/g and a melting temperature of 304.64 °C. In the solidification cycle, it requires 87.32 J/g heat dissipation to phase change and solidify at 302.03 °C. A weight loss of 0.00619 g after 50 cycles of phase change for NaNO 3 /Diatomite/Nano EG SS-PCM shows a reliable SS-CPCM. The same optimum pellet with only a different Nano material of Nano diamond has a latent heat of 91.02 J/g and a melting temperature of 304.98 °C. In the solidification cycle, it requires 90.51 J/g heat dissipation to phase change and solidify at 302.14 °C.