Development of Phase Change Materials Based on Mixtures of Salt Hydrates Through Theoretical Prediction and Experimental Investigation

DOI

10.2991/ahe.k.210202.003How to use a DOI?

Keywords

thermal energy storage, latent heat storage, phase change materials (PCM), salt hydrates, modified BET model

Abstract

Latent heat storage using phase change materials (PCM) provides thermal energy storage systems with high storage capacities in small temperature ranges. Most of the PCM used in applications undergo a phase change from solid to liquid and vice versa storing heat in repeated melting and crystallization processes. To select a suitable PCM, both melting and crystallization have to match the temperature range of the intended application. In the temperature range from 0 °C to 100 °C, salt hydrates are generally both cheaper and offer higher volumetric melting enthalpies than comparable organic PCM. However, in certain application-relevant temperature ranges, there is a lack of PCM based on salt hydrates. Since most salt hydrates are known, mixtures of salt hydrates and salts are being investigated. In order to identify interesting mixture compositions (for example eutectics) and to reduce the experimental effort, prediction models are applied to calculate solid-liquid phase diagrams. In the research project properPCM, the modified BET model was applied to calculate solid-liquid phase diagrams of mixtures of salt hydrates and salts. Up to now, 44 ternary phase diagrams with 151 eutectics were predicted. So far, 40 selected predicted eutectics have been experimentally investigated via differential scanning calorimetry (DSC). 16 of the eutectics that were successfully verified via DSC were subsequently subjected to thermal cycling stability tests. Thereby, samples of about 100 ml have been tested in self-built thermal cycling test rigs. In order to assess the thermal cycling stability, special focus is put on the visual observation of potential phase separation of the mixtures. In the future, the developed method can be applied to create PCM based on mixtures of salt hydrates for application-relevant temperature ranges.

Copyright

© 2021, the Authors. Published by Atlantis Press.

Open Access

This is an open access article distributed under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).

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TY  - CONF
AU  - Christoph Rathgeber
AU  - Henri Schmit
AU  - Stefan Hiebler
AU  - Peter Hoock
PY  - 2021
DA  - 2021/02/04
TI  - Development of Phase Change Materials Based on Mixtures of Salt Hydrates Through Theoretical Prediction and Experimental Investigation
BT  - Proceedings of the 14th International Renewable Energy Storage Conference 2020 (IRES 2020)
PB  - Atlantis Press
SP  - 14
EP  - 18
SN  - 2589-4943
UR  - https://doi.org/10.2991/ahe.k.210202.003
DO  - 10.2991/ahe.k.210202.003
ID  - Rathgeber2021
ER  -