A comprehensive evaluation on the cycling stability of sugar alcohols for medium-temperature latent heat storage

Sugar alcohols have been proposed as a class of potential phase change materials (PCMs) for medium-temperature latent heat storage . The present work investigated the cycling stability of four pure and three mixture sugar alcohols by a specially-designed test setup, followed by a comprehensive evaluation based on their phase change behaviors (reported in our previous publication) and stability. It was found that the latent heats of fusion/crystallization degrade upon consecutive melting-crystallization cycles, and a higher degree of superheat Δ T sh leads to a faster degradation. An extremely low level of only 10.5 % degradation was obtained for erythritol after 200 cycles at a relatively low Δ T sh of 20 °C. The corresponding degrees of supercooling Δ T sc become higher due to the remarkable reduction of crystallization temperatures . It was shown that introducing protective nitrogen gas could suppress oxidation and improve cycling stability. The cycles of half degradation on latent heat of fusion was ~3.6 times with nitrogen protection. A comprehensive evaluation identified that the crystallization-related issues and poor stability are the primary challenges for sugar alcohols. Nevertheless, other than common PCMs, some particular application scenarios like controllable latent heat retrieval and seasonal heat storage can be hopefully developed by virtue of the deep supercooling nature of sugar alcohols.