Stable, low-cost phase change material for building applications: The eutectic mixture of decanoic acid and tetradecanoic acid. (15th April 2016)

• Record Type: Journal Article
• Authors: Kahwaji, Samer; Johnson, Michel B.; Kheirabadi, Ali C.; Groulx, Dominic; White, Mary Anne
• Is Part Of: Applied energy. Volume 168(2016)
• Page Start: 457
• Page End: 464
• Publication Date: 2016-04-15
• Subjects: Phase change material -- PCM -- Eutectic -- Thermal properties; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2016.01.115
• Languages: English
• ISSNs: 0306-2619

Abstract

Graphical abstract: Highlights: Decanoic/tetradecanoic acid eutectic at 0.82 ± 0.02 mole fraction (78 ± 2 mass%) decanoic acid. Melting of eutectic at 20.5 ± 1.5 °C, useful for building applications. High enthalpy change, 153 ± 15 J g − 1, is promising. Negligible change in stability after 3000 melt–freeze cycles. Abstract: We present a thorough characterization of the thermal properties and thermal reliability of the eutectic mixture of decanoic acid with tetradecanoic acid, as a phase change material (PCM) of potential interest for passive temperature control in buildings. From the temperature-composition binary phase diagram we found that the eutectic composition is 0.82 ± 0.02 mole fraction (78 ± 2 mass%) decanoic acid. We thoroughly characterized the thermal properties of the eutectic mixture. The eutectic composition has a high latent heat of fusion Δfus H = 153 ± 15 J g − 1 and a melting temperature T onset = 20.5 ± 1.5 °C. The heat capacity measured as a function of temperature for the solid and liquid phases just below and above the melting point is 1.9 and 2.1 ± 0.2 J K − 1 g − 1, respectively. The average value of the thermal conductivity of the solid phase measured between −33 and 9 °C is κs = 0.20 ± 0.02 W m − 1 K − 1 and for the liquid phase, the thermal conductivity is κl = 0.23 ± 0.03 W m − 1 K − 1 for 28 and 38 °C. The mixture has a good long-term thermal stability as indicated by negligible changes in Δfus H and T onset after 3000 melt–freeze cycles. The parameters determined in this work allow more accurate modeling and optimization of the behavior of the eutectic mixture in preparation for implementation as a thermal energy storage PCM.