Preparation and characterization of paraffin/palygorskite shape-stable composite phase change materials for thermal energy storage

With the depletion of energy, energy efficiency received more and more attention. Thermal energy storage (TES) using latent heat of phase change materials can balance the non-equalizing distribution of heat in time and space, and improve energy utilization. In this work, Raw palygorskite (Raw-PAL) was used as the carrier to prepare paraffin/palygorskite shape-stable composite phase change materials (CPCM) through a novel pretreatment by alkalization, acidification and calcination. The Raw-PAL after treatment by the combination of alkalization/ calcination/ acidification (PAL-3) has the maximum adsorption capacity for paraffin. The micromorphology, chemical compatibility, thermal properties and stability of paraffin/PALs were studied. The results of BET and SEM showed that the pretreatment can increase the specific surface area and pore volume of PAL, which has a positive significance to improve the paraffin mass fraction in CPCM. DSC results indicated that the melting enthalpy and melting temperature of paraffin/PAL-3 are 89.2 J/g and 58.55 degrees C respectively. After cyclic test for 300 times, the melting enthalpy of paraffin/PAL-3 can still maintain 96.2% of the initial value and the shape remained unchanged at 80 degrees C for 12 h. The results showed that the paraffin/PAL-3 CPCM was a shape-stable phase change material with potential application.