Experimental research on an environment-friendly form-stable phase change material incorporating modified rice husk ash for thermal energy storage

In this paper, a novel environment-friendly form-stable phase change material (PCM) was prepared by use of a mechanical mixing and the impregnation method for thermal energy storage. An agricultural solid waste rice husk ash (RHA) was acted as supporting material due to its natural high porosity and surface area, as well as organic paraffin (PA) was selected as core material used for heat storage. Particularly, acid-treated RHA with higher loading capacity compared to rough RHA was used as a support to stabilize PA. X-ray fluorescence method (XRF) and nitrogen adsorption analysis (N₂ adsorption) indicated that the impurities within RHA was effectively removed, the pore volume and specific surface area were increased by 37.3% and 54.2% after acid treatment. The leakage test exhibited that the prepared PA/RHA containing 50 wt% PA can maintain solid shape without leakage in melting state of organic PA. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy (ATR-FTIR) results suggested that there was no chemical reaction occurred between PA and RHA with the superior combination. Differential scanning calorimetry (DSC) was used to record the phase change properties of PA/RHA with the phase change temperature of 51.5 °C and latent heat of 68.1 J/g. Moreover, the prepared composite PCM maintained favorable thermal cycling reliability, being subjected to 200 thermal cycles. Furthermore, Thermal gravimetric analysis (TGA) illustrated a beneficial effect of RHA on the thermal stability of PA. Therefore, the prepared composite PCM can be regarded as a potential environment-friendly candidate for thermal energy storage in building energy efficiency.