Phase change performance assessment of salt mixtures for thermal energy storage material

Abstract

Summary The phase transition performance of the CaCl2 · 6H2O–Ca(NO3)2 · 4H2O composite salt system with nucleating and thickening agents was investigated in this paper. The CaCl2 · 6H2O–Ca(NO3)2 · 4H2O composite salt system was prepared by adding Ca(NO3)2 · 4H2O (12 wt%) to CaCl2 · 6H2O. Different nucleating agents including SrCl2 · 6H2O, SrCO3, BaCl2, BaCO3, Na2B4O7 · 10H2O, H3BO3 and NH4Cl were used to address the problems of phase segregation and supercooling phenomena during the phase change process. The results show that the single nucleating agent SrCl2 · 6H2O or the mixture of nucleating agents with 2 wt% SrCl2 · 6H2O, 1 wt% BaCl2 and 0.5 wt% of thickening agent carboxyl methyl cellulose is the most suitable for this system. The latent heat remained constant at about 116 J/g before and after adding the agents. Density functional theory was used to further investigate the microstructure‐related reason for the salt–water separation and supercooling phenomena. It can be deduced that the hydrogen bond is the vital factor involved during the phase transition. The aim of adding thickener was to form more hydrogen bonds which encapsulated the hydrated species and made it difficult to lose the hydrated waters. The main purpose of adding nucleating agent was to break the metastable state among microscopic species. The results of this work indicate that the CaCl2 · 6H2O–Ca(NO3)2 · 4H2O salt mixture has potential as a thermal energy storage material. Copyright © 2017 John Wiley & Sons, Ltd.

Understanding the Behaviour of Real Metaborates in Solution

“…The abstraction of the first hydride from KBH 4 is thought to be the rate‐determining step. [37] All of the borohydride ions react with water, and the degree of conversion depends on the time and the reaction conditions. The fact that the hydrogen yield decreases when the reaction is run at higher concentrations reflects the formation of these complex metaborate intermediates.…”

Preparation, Characterization, and Modification of Sodium Acetate Trihydrate-Urea Binary Eutectic Mixtures As Phase Change Material

“…The eutectic PCMs have the lowest melting temperature in the entire composition range of mixtures of individual phase change materials and the advantages of sharp melting and solidification without any phase segregation, which may provide the desired thermophysical properties for required applications . Most reported eutectics include inorganic–inorganic, especially eutectic hydrated salt (e.g., MgCl 2 ·6H 2 O–Mg­(NO 3 ) 2 ·6H 2 O, CaCl 2 ·6H 2 O–MgCl 2 ·6H 2 O, Na 2 CO 3 ·10H 2 O–Na 2 HPO 4 ·12H 2 O, CaCl 2 ·6H 2 O–Mg­(NO 3 ) 2 ·6H 2 O, CaCl 2 –NH 4 Cl–H 2 O, CaCl 2 ·6H 2 O–Ca­(NO 3 ) 2 ·4H 2 O, etc. ), and organic–organic (e.g., fatty acid eutectic mixtures, fatty alcohol eutectic mixtures, fatty alcohol–fatty acid eutectic mixtures, etc.).…”

Form‐stable Na 2 SO 4 ·10H 2 O‐Na 2 HPO 4 ·12H 2 O eutectic/hydrophilic fumed silica composite phase change material with low supercooling and low thermal conductivity for indoor thermal comfort improvement

“…And Xie et al showed that 50 wt% Na 2 SO 4 ·10H 2 O‐50 wt% Na 2 CO 3 ·10H 2 O eutectic system possessed a suitable phase transition temperature (25.41°C) and good melting enthalpy (195.3 kJ·kg −1 ) for building energy storage. Other researchers also prepared binary EHSs with the proper phase transition temperatures for indoor thermal comfort . These above‐mentioned researches about EHS were summarized in Table .…”

“…Other researchers also prepared binary EHSs with the proper phase transition temperatures for indoor thermal comfort. [25][26][27][28] These abovementioned researches about EHS were summarized in Table 1.…”