Fabrication and thermal characterization of kaolin-based composite phase change materials for latent heat storage in buildings

Abstract

Three kinds of kaolin-based composite phase change materials (Kb-CPCMs) including capric acid (CA), PEG600, and heptadecane (HD) as organic PCMs were fabricated using vacuum impregnation method for latent heat storage (LHS) application in buildings. The surface morphology, compatibility, maximum ratio for impregnated PCM, LHS properties, thermal endurance, thermal conductivity and its effect on the melting times of prepared Kb-CPCMs were investigated by using microscopy, spectroscopy, calorimetry and thermal methods. The seepage test indicated that CA, PEG600 and HD were impregnated maximally into the kaolin as 17.5, 21 and 16.5wt%, respectively. The fabricated three composites, K/CA, K/PEG600, and K/HD, have a phase change temperature of 30.71, 5.16 and 22.08°C and a latent heat of 27.23, 32.80 and 34.63J/g, respectively. The thermal cycling test exposed that the thermal reliability of the Kb-CPCMs slightly changed after repeated 1000 heating-cooling cycling. The heat storage rates of the Kb-CPCMs were increased considerably by adding expanded graphite (EG) in mass faction of 5%. All the prepared Kb-CPCMs have good thermal energy storage (TES) function for heating, ventilating and air conditioning (HVAC) in building envelopes because of their suitable LHS properties, high reusability performance and enhanced thermal conductivity.