Study on the apparent specific heat of sugar alcohol slurries

Abstract

Sugar alcohols are used as heat storage materials, having a high latent heat. Their melting points are suitable for the recovery and reuse of unused heat at medium/low temperatures. A sugar alcohol slurry is a heat transfer medium in which solid sugar alcohol particles are dispersed in an aqueous solution that can efficiently transport heat through pipes to where there is heat demand. In this study, the apparent specific heat of sugar alcohol slurries was investigated to estimate the heat storage amount. Erythritol and mannitol were used as the sugar alcohols. The apparent specific heat was measured experimentally, and a model of the apparent specific heat of the slurry is proposed. The enthalpy difference between the solid and liquid sugar alcohol owing to freezing-point depression was considered in the model. The results showed that apparent specific heat increased with temperature and peaked 3–5°C below the saturation temperature. The maximum value of apparent specific heat of the slurry increased with initial concentration. The experimental and calculated values were compared to validate the model. The apparent specific heat values calculated with the model showed good agreement with the experimental values and freezing-point depression had a large effect on the apparent specific heat of the sugar alcohol slurries. The proposed model is valuable to design heat transport and storage systems using sugar alcohol slurries.