Lipid‐derived monoamide as phase change energy storage materials. (22nd July 2019)

• Record Type: Journal Article
• Authors: Poopalam, Kosheela D.; Raghunanan, Latchmi; Bouzidi, Laziz; Yeong, Shoot Kian; Narine, Suresh S.
• Is Part Of: International journal of energy research. Volume 43:Number 13(2019)
• Page Start: 6934
• Page End: 6950
• Publication Date: 2019-07-22
• Subjects: phase change materials -- latent heat storage -- structure‐property correlations -- solid‐liquid amide PCMs -- lipid‐derived monoamide -- polymorphism; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Power resources -- Research -- Periodicals; 621.042
• DOI: 10.1002/er.4711
• Languages: English
• ISSNs: 0363-907X

Abstract

Summary: One of the major shortcomings of current organic phase change materials (PCMs) is their relatively low melting points, typically below 80°C, which limits their integration into thermal energy storage (TES) systems. The present work was aimed at developing lipid‐derived PCMs with increased melting points which would be suitable for TES applications requiring higher melting points without compromising other key properties such as enthalpy. The introduction of an amide group into the structure of linear saturated fatty acids was used as a means to increase intermolecular interactions and therefore crystallization and melting points. A series of six linear monoamides with differing chain length and symmetry about the amide group were investigated for thermal stability, thermal transition, flow behavior, and crystal structure to establish the structure‐property relationships relevant to TES. The presence of the highly polar amide group in the aliphatic fatty acid–derived molecules resulted in notable improvement in performance compared with the analogous monofunctional molecules: Increases in melting points (79°C‐96°C) and high enthalpies of fusion (155‐201 J/g) were recorded. Fundamental relationships between structure, processing, and macroscopic physicochemical properties, never before elucidated, were revealed in the study. The study revealed a step‐like variation of macroscopic properties: a surprising outcome of the competition between intermolecular attractions, symmetry effects, and mass transfer limitations. The predictive structure‐function relationships established in this work will allow the straightforward engineering of monoamide architectures that can extend the range of organic PCMs and deliver thermal properties desirable for TES applications. Abstract : Important new relationships between structure, processing conditions, and macroscopic properties of aliphatic monoamides were established. The critical roles played by hydrogen bonds, van der Waals attractions, and their competition with mass and symmetry effects were uncovered. The predictable structure‐function relationships established can lead to the custom engineering of monoamide molecular architectures which deliver targeted phase change properties. The monoamides studied demonstrated significantly higher phase change temperature and enthalpies compared with existing organic PCMs, expanding the range of current applications in thermal energy storage.