Reduction of Rotation Phase Supercooling in N-Docosanol Nano Phase Change Slurries

Phase Change Slurries (PCS) are an efficient medium for isothermal energy storage and transportation (Lane 1992). In nanometre-sized dispersion droplets, supercooling decreases the available heat capacity in a specific temperature range due to a shift in the phase change temperatures. Since PCM are mostly used in applications with narrow operating temperature interval, supercooling can lead to unusability of PCS (Safari et al. 2017). Differential Scanning Calorimetry (DSC) is used in combination with X-ray diffraction (XRD) to characterize the PCS prepared by ultrasonication. We confirm that n-docosanol exhibits similar rotation phases as previously observed in linear alkanes (Sirota 1998). With decreasing particle size, the phase transitions separate to lower temperatures. Upon addition of nucleation agents, the degree of supercooling could be reduced significantly for some phases. A model for the n-docosanol crystallization was developed, which helps to understand supercooled rotation phases and simplifies the transfer to other organic PCS.