Abstract
This study investigated a novel idea of combining a polyalcohol with an inorganic salt hydrate to prepare new PCMs suitable for domestic water heating. Specifically, the heat storage characteristics of a eutectic mixture of erythritol and MgCl2 6H2O were evaluated. DSC analysis indicated that mixtures that contained less than 20wt% MgCl2 6H20 have melting points above 80°C and latent heat values greater than 120kJ/kg. Thermal cycling of erythritol-based PCMs in test tubes showed good stability in terms of nucleation temperature, melting point and latent heat of fusion after several heating-cooling cycles. The erythritol-based PCMs were found to undergo supercooling of about 50°C below the melting point, similar to erythritol. An evaluation of the specific heat, density and thermal conductivity of a mixture of erythritol and 10wt% MgCl2 6H2O indicated that thermal properties of the mixture were potentially useful for domestic water heating. In a scale-up experiment, the solidification of a mixture of erythritol and 10wt% MgCl2 6H2O was conducted using a visualization unit with a cooling vertical double-pipe. Analysis of the distribution of the salt hydrate component in the solid phase revealed the salt hydrate's possibility of accumulating at the bottom of the unit. This behavior was probably due to density differences between the mixtures' components. The effect of ultrasonic irradiation on the mixture's supercooling relaxation and component distribution was also investigated.
