Preparation and characterization of capric-myristic-stearic acid eutectic mixture/modified expanded vermiculite composite as a form-stable phase change material. (15th September 2016)

• Record Type: Journal Article
• Authors: Wei, Haiting; Xie, Xiuzhen; Li, Xiangqi; Lin, Xingshui
• Is Part Of: Applied energy. Volume 178(2016)
• Page Start: 616
• Page End: 623
• Publication Date: 2016-09-15
• Subjects: Expanded vermiculite -- Capric-myristic-stearic acid -- Carbonize -- Acid treatment -- Form-stable composite PCM; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2016.06.109
• Languages: English
• ISSNs: 0306-2619

Abstract

Graphical abstract: Highlights: The expanded vermiculite/carbon (EVC) was obtained by in-situ carbonizing CTAB. The acid treated EVC (aEVC) was an optimum CA-MA-SA supporting matrix. The melting latent heat of the CA-MA-SA/aEVC was 86.4 J/g at 22.92 °C. The thermal conductivity of CA-MA-SA/aEVC was 0.667 W/mK. The CA-MA-SA/aEVC composite PCM has good thermal and chemical stabilities. Abstract: A novel capric-myristic-stearic acid (CA-MA-SA)/modified expanded vermiculite composite phase change material (PCM) with simultaneously enhanced thermal conductivity and latent heat was prepared in this study. The expanded vermiculite/carbon composite (EVC), obtained by in-situ carbonizing cetyl trimethyl ammonium bromide in the layer of expanded vermiculite, was treated with nitric acid (aEVC) to be used as the CA-MA-SA supporting matrix. The results showed that the thermal conductivity of CA-MA-SA/aEVC was greatly enhanced by introducing carbon and the CA-MA-SA adsorption capacity was improved by the acid-treatment of EVC. The thermal conductivity of CA-MA-SA/aEVC was 0.667 W/mK, which was 31.6% higher than that of CA-MA-SA/expanded vermiculite (EV). The latent heats of the CA-MA-SA/aEVC were 86.4 J/g at the melting temperature of 22.92 °C and 80.43 J/g at the freezing temperature of 21.03 °C, which were also greatly higher than those of CA-MA-SA/EV. The results of the thermo-gravimetric analysis (TGA), thermal cycling test and Fourier transform infrared spectroscopy (FT-IR) indicated that the CA-MA-SA/aEVC composite PCM was thermally stable and chemically inert. Thus, the prepared CA-MA-SA/aEVC composite PCM is a promising material for the building energy efficiency applications.