Observation of Phase Segregation Phenomenon of Latent Heat Storage Material Na2HPO4·12H2O Melt and Supposition on Its Generation Mechanism

Yasuyuki Watanabe*, Izumi Hirasawa

*この研究の対応する著者

研究成果: Article査読

抄録

Disodium hydrogen phosphate dodecahydrate is as a latent heat storage material that is expected to be applied to indoor air conditioning and floor heating, especially medical applications. However, the heptahydrate, which has a different number of crystal water from the dodecahydrate, can exist stably at a temperature higher than the melting point of the dodecahydrate. Owing to the crystallization and the subsequent accumulation of the heptahydrate in the dodecahydrate melt, during a long-term thermal cycle of heat storage and heat release, the amount of latent heat of the dodecahydrate gradually decreases. In this study, in order to suppress the occurrence of such phase segregation, the melting and freezing behavior when applying a thermal cycle to the dodecahydrate was observed in detail. As a result, it was clarified that the occurrence of phase segregation not only reduces the latent heat amount of the dodecahydrate, but also lowers the nuclearization temperature thereof. The occurrence of phase segregation due to the crystallization of heptahydrate was thought to be due to the decrease in the diffusion rate during the dissolution process of the heptahydrate. It was suggested that, if the concentration polarization of the Na2HPO4 component forming in the melt was eliminated, for example, by installing a stirring mechanism in the heat storage device, the liquidus line of the heptahydrate would be substantially dissolved and the occurrence of phase segregation could be prevented.

本文言語English
ページ(範囲)152-160
ページ数9
ジャーナルkagaku kogaku ronbunshu
48
4
DOI
出版ステータスPublished - 2022

ASJC Scopus subject areas

  • 化学 (全般)
  • 化学工学(全般)

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