Low melt alloy enhanced solid-liquid phase change organic sugar alcohol for solar thermal energy storage

this work, the thermo-physical behavior along with the energy storage performance of low melting alloy (LMA) mixed with D-Mannitol (DM)-a solid-liquid PCM, were experimentally investigated. LMA is an alloy consisting of Tin (59%), Bismuth (32%), Zinc (4%) and Indium (5%). Composites with different mass loadings of LMA (0.1% and 0.5%) were prepared using a low energy ball mill. A maximum thermal conductivity enhancement of similar to 8% and similar to 24% was found with the use of 0.1 wt% and 0.5 wt% LMA, respectively. The effect on melting point due to the addition of LMA particles was relatively small, however the change in solidification temperature indicates that the nucleating capabilities of LMA helped reduce the sub-cooling temperature, during the discharging process. 350 repetitive melting/freezing cycles were conducted to study the effect of thermal cycling on the PCM, and though the results showed a decrease in enthalpies, the base PCM still had a very high latent heat of 225 kJ/kg. Further, the kinetics of crystallization (non-isothermal) showed a dramatic increase in the crystallization rate of the composite, after the addition of the LMA particles. The structural, thermal and chemical stability performance of the PCM were studied using XRD, TGA and FTIR techniques respectively. While the XRD spectra revealed that the PCM was structurally stable, the FTIR data showed that no new chemical bonds were formed in the composite PCM. Moreover, the prepared composite retained thermal stability up to a temperature of <300 degrees C. The energy storage and discharging characteristics of the PCM composites were studied using an experimental setup. The results showed that the time taken for the completion of one cycle was reduce similar to 25% for 0.5 wt% DM-LMA composites. From the results obtained, the potential for using DM-LMA as a new PCM composite is evident. Thus, with an enhanced thermal transport, energy storage and release performance, DM-LMA is a promising candidate for efficient storage, recovery and utilization of solar heat and industrial waste heat applications. (C) 2018 Elsevier B.V. All rights reserved.