A eutectic mixture of galactitol and mannitol as a phase change material for latent heat storage

Abstract

a b s t r a c tThe thermophysical properties of mixtures of galactitol and mannitol were examined via differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD) analysis. The aforementioned sugars were found to form a eutectic mixture at a 30:70 molar ratio of galactitol and manntitol, and displayed a melting point of 153°C while maintaining a high latent heat of fusion (DH fus = 292 J g À1 ). The XRD data revealed that the eutectic mixture contained the a, b, and d forms of mannitol with the d form being the major component. By varying the temperature ramp rates utilized in the DSC measurements from 0.5°C min À1 to 20°C min À1 , the heat of crystallization as well as the crystallization temperature increased (c.f., DH crys : 64 J g À1 ? 197 J g À1 ; T c : 68°C ? 105°C). In addition, the temperature and the enthalpy of crystallization were also improved by up to 34% through the addition of small quantities (up to 0.5 wt%) of nucleating agents, such as graphite powder or silver iodide. After 100 heating/cooling cycles under an atmosphere of nitrogen, the heat of fusion of the eutectic mixture decreased by only 4% with no change in the melting point, and the mixture appeared to be chemically stable according to a Fourier transform infrared (FT-IR) spectroscopic analysis. Collectively, these data indicate that the eutectic mixture exhibits excellent cyclic stability under ambient atmospheres and offers potential for use in thermal energy storage applications.

Preparation and Characterization of Erythritol/Graphene Oxide Shape‐Stable Composites with Improved Thermal‐Physical Property

“…P. Hu declaimed that SAT containing 5 wt% AlN nanoparticles and 4 wt% CMC had no supercooling phenomenon while latent heat only decreased from 238.54 J g −1 to 227.54 J g −1 . However, another viewpoint maintained that the increased viscosity of system would restrict the diffusion of molecules from the melt to the nucleus, and thus resulted in the worsening of suppercooling and lowering speed of crystallization and heat transfer …”

“…As an typical example, S. Zhang declared that well dispersed nanoparticles provided stable foreign nuclei to promote the heterogeneous nucleation and accelerate crystallization process. On the other hand, dynamic nucleation is another effective method to trigger crystallization because supercooling is also a kinetic controlled issue . Dynamic stimulation employs external stimuli, including mechanical vibration, stirring and ultrasonic irradiation, as supplementary energy to induce the nucleation of crystals .…”

Review on system and materials requirements for high temperature thermal energy storage. Part 1: General requirements

“…They observed the same poor stability results than Solé et al [36] and concluded that this TES material is not suitable for the application proposed. Paul et al [38] studied the chemical stability of a eutectic mixture at a 30:70 molar ratio of galactitol and mannitol (T m = 153 ºC) via DSC, X-ray powder diffraction (XR) and FT-IR spectroscopy analyses. Those techniques confirmed that the combination of mannitol and galacticol showed good cyclic, thermal and chemical stability compared to its individual components under nitrogen or air atmospheres.…”

“…When that occurs, PCM shows a significantly lower capacity to store heat [33]. According to [38] studied the effect of adding up to 0.5 wt.% of different nucleating agents (graphite and silver iodide) into an eutectic mixture at a 30:70 molar ratio of galactitol and mannitol (T m = 153 ºC).…”

Preparation and Thermal Properties of Stearic Acid/n‐Octadecane Binary Eutectic Mixture as Phase Change Materials for Energy Storage

“…Moreover, the melting temperature can be adjusted to a suitable value by making a binary, trinary or even polynary eutectic in order to meet the practical applications. The paraffin and unitary, binary or even polynary fatty acids have well been studied as PCMs . However, as far as we know, the studies on fatty acid/n‐alkane mixture as PCMs is very few in the open literature.…”