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Phase change performance assessment of salt mixtures for thermal energy storage material
Author(s) -
Zhu F. Y.,
Zhou H. X.,
Zhou Y. Q.,
Ge H. W.,
Fang W. C.,
Fang Y.,
Fang C. H.
Publication year - 2017
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.3747
Subject(s) - supercooling , nucleation , salt (chemistry) , metastability , thermal energy storage , chemistry , microstructure , phase (matter) , hydrogen bond , composite number , chemical engineering , phase transition , crystallization , thermodynamics , materials science , composite material , crystallography , organic chemistry , molecule , physics , engineering
Summary The phase transition performance of the CaCl 2 · 6H 2 O–Ca(NO 3 ) 2 · 4H 2 O composite salt system with nucleating and thickening agents was investigated in this paper. The CaCl 2 · 6H 2 O–Ca(NO 3 ) 2 · 4H 2 O composite salt system was prepared by adding Ca(NO 3 ) 2 · 4H 2 O (12 wt%) to CaCl 2 · 6H 2 O. Different nucleating agents including SrCl 2 · 6H 2 O, SrCO 3 , BaCl 2 , BaCO 3 , Na 2 B 4 O 7 · 10H 2 O, H 3 BO 3 and NH 4 Cl 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 SrCl 2 · 6H 2 O or the mixture of nucleating agents with 2 wt% SrCl 2 · 6H 2 O, 1 wt% BaCl 2 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 CaCl 2 · 6H 2 O–Ca(NO 3 ) 2 · 4H 2 O salt mixture has potential as a thermal energy storage material. Copyright © 2017 John Wiley & Sons, Ltd.