MODELING OF THE PHASE CHANGE MATERIAL OF A HYBRID STORAGE USING THE FINITE ELEMENT METHOD
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Beschreibung
To increase the efficiency of energy-intensive industrial processes, thermal energy storages can offer new possibilities. In recent years, especially latent heat thermal energy storages, exploiting the high energy density of phase change material (PCM), are becoming widely applied in industry.A novel approach is investigated in the project HyStEPs, funded by the Austrian Research Promotion Agency (FFG) with grant number 868842. In this concept, containers filled with PCM are placed at the shell surface of a Ruths steam storage, to increase storage efficiency.In this work, a two-dimensional model using the finite element method is developed to simulate the PCM of the hybrid storage as designed in the HyStEPs project. The apparent heat capacity method is applied in a MATLAB implementation, considering heat transfer by both conduction and natural convection. This successfully validated code can handle any desired layout of materials arranged on a rectangular domain. Furthermore, a parameter study of different dimensions and orientations of the PCM cavity was conducted. The impact of natural convection was found to lead to significantly varying behaviour of the studied cavities with different orientation during the charging process, while it was found to be negligible during the discharging process.
The progressive decarbonisation process and the increased share of renewable energy sources in the grid has increased the need for the development of new approaches to store energy and to increase the efficiency of industrial processes. Increasingly, latent heat thermal energy storage systems are being used, which exploit phase change materials to store a large amount of energy during the phase change. A novel approach to increasing the efficiency of the commonly used Ruths steam storage is currently being investigated in the project HyStEPs, a project funded by the Austrian Research Promotion Agency (FFG) with grant number 868842. In this concept, a container filled with phase change material is placed at the shell surface of the Ruths steam storage.In this diploma thesis, and in contribution to the HyStEPs project, the phase change material of this hybrid storage is modelled in two dimensions using the finite element method. The apparent heat capacity method is applied in aMATLAB implementation and considers heat transfer by both conduction and natural convection. Furthermore, the developed code can handle any desired layout of materials arranged on a rectangular domain. The model was successfully validated using an analytical solution and experimental data, and a cross-validation showed corroboration with the results of the CFD software ANSYS Fluent. A parameter study was conducted and the behaviour of different dimensions and orientations of the phase change material cavity was investigated. The effect of natural convection was found to cause significantly varying behaviour of the studied cavities with different orientation during the charging process, while the effect was found to be negligible during the discharging process.
Autor*in
Lukas Kasper
Themen in »MODELING OF THE PHASE CHANGE MATERIAL OF A HYBRID STORAGE USING THE FINITE ELEMENT METHOD«
Phasenübergang numerical modeling finite element method latent heat storage Finite-Elemente-Methode phase change Latentwärmespeicher Numerisches Modell Hybridspeicher hybrid storage