Bio-based hexadecanol impregnated fly-ash aggregate as novel shape stabilized phase change material for solar thermal energy storage

Abstract

In light of a variety of latent heat storage materials being available, the concept of utilization of organic PCMs for solar thermal energy storage (STES) is becoming increasingly attractive during the recent past. From this perspective, the present study is aimed at developing a new bio-based shape stabilized phase change material (BSPCM) for achieving passive cooling in buildings through STES. An eco-friendly BSPCM composite, consisting of the hexadecanol as the PCM and the modified porous fly ash-based pebbles as the supporting matrix, was prepared using the vacuum impregnation technique. The prepared BSPCM was then characterized thoroughly with respect to its morphology, crystal and surface structures, phase change properties, thermal stability, leakage stability, thermal conductivity and thermal reliability.The surface morphology of BSPCM has clearly showed the presence of PCM in the porous fly ash-based pebbles. The highly crystalline peaks of the PCM were also observed to be retained after the formation of the BSPCM. The chemical compatibility between PCM and fly ash supporting material was well established as confirmed by the surface structure analysis. The BSPCM has exhibited a fusion enthalpy of 114.41 kJ/kg and also the thermal stability of which was found excellent. Besides, the stability of the BSPCM against leakage was observed up to 85 °C, which is reasonably higher than that of the PCM's operating temperature. The thermal conductivity of the BSPCM composite was measured to be 0.3397 W/mK, which is quite favorable for reducing the infiltration of solar radiation through the building structure. Moreover, the BSPCM, after subjecting to 1000 melting and freezing cycles, has demonstrated excellent thermal reliability. Hence, with these promising thermophysical properties, the prepared eco-friendly BSPCM composite has exhibited its viability for achieving passive cooling through STES and that would be of greater advantage for the buildings of the future.