NON-ISOTHERMAL PHASE CHANGE BEHAVIORS OF BINARY MIXTURES OF D-DULCITOL AND PENTAERYTHRITOL AS NOVEL HEAT STORAGE MATERIALS

摘要

As a promising Phase Change Material (PCM) candidate for low-to-medium temperature (100-250°C) latent heat storage, sugar alcohols undergo serious supercooling during cool-down for crystallization. Technical efforts need to be dedicated to suppression or control of the supercooling of sugar alcohols. In this work, the supercooling of D-dulcitol, with a melting point of around 186°C, was attempted to be reduced by mixing with a solid-solid PCM Pentaerythritol (PE) as the nucleation agent, which has a solid-solid phase transition temperature (～186°C) similar to the melting point of d-dulcitol. Such novel binary mixtures were prepared by dispersing PE powders at various mass fractions into d-dulcitol melt. The non-isothermal phase-change-related properties, with emphasis on the crystallization properties, were tested on a heat-flux differential scanning calorimeter at a constant heating/cooling rate of 5°C/min. The preliminary results showed that both the crystallization point and latent heat of crystallization strongly depend on the mass fraction of PE, and both decrease in magnitude with the increasing in mass fraction of PE. The degree of supercooling of the binary mixtures also depend on the mass fraction of PE, and a reduction of up to 10°C was obtained at 50 wt.% PE, as a result of the decrease in the melting points of the binary mixtures.