PHASE CHANGE TRANSITION OF WAX FILLED WITH NANOSIZED CLAYS DURING HEAT ACCUMULATION

Phase change materials (PCMs) have the potential to significantly decrease energy operation and associated carbon emissions. Bio-wax-based PCMs are rational solution that have the potential to have a significant impact on heating and cooling loads in various climatic locations. The values of melting enthalpies for Carnauba wax are significant and are around 200 J/g. Clays are often added to the organic components to achieve enhancing thermal conductivity is an effective approach to improve PCMs. Optimizing the type of heat exchanger for PСMs should include information on the nature and mechanism of the phase transition of the material. Shape-stable materials with a phase transition were obtained from melts by mixing halloysite or montmorillonite clays with Carnauba wax. The peculiarities of the behavior of materials during heating and quantitative data on heat accumulation were determined by the DSC method. The types of thermal accumulation in materials with a phase transition are discussed. X-ray analysis confirmed the formation of waxy crystalline materials. Powder X-ray diffraction data revealed the process of amorphization of heated samples by changing the degree of crystallinity. The multi-stage mechanism of heat accumulation by wax materials has been confirmed. IR spectra of Carnauba wax, wax with halloysite nanotubes (1 : 1) and wax with montmorillonite clay (1 : 1) samples were measured in the temperature range that includes the melting process. The regularities of changes in intensities and the position of the absorption bands of the materials were established. Bibl. 21, Fig. 6.