Phase change material is crystallised
With micro-encapsulated or emulsified organic phase change materials,
the solidification temperature is frequently below the melt temperature.
This so-called undercooling is a hindrance for many applications. By
means of systematic investigations, the researchers achieved a
fundamental understanding of the physical principles. Based on the
experimental findings, models developed that make it possible to
forecast the crystallisation properties.
|Project status||Project completed|
|Phase change||Latent heat|
|Project duration||September 2012 until August 2016|
One of the fundamental problems using phase change materials is the effect of subcooling. This prevents a wider use of this very promising thermal storage technology. Therfore this project aims to investigate the supercooling phenomenum by systematic studies to gain fundamental knowledge of the mechanisms behind supercooling and nucleation of microenccapsulated and emulsified organic PCM. Thus, an improvement of the properties of microcompartimented organic PCM will be possible in the future. This will allow the development of new highly efficient latent heat storage applications.
The research focus is on the investigation of the supercooling phenomena of organic PCM micro compartments. Especially supercooling of microencapsulated and emulsified PCM will be investigated. The final target is to develop a model for the mechanisms leading to supercooling in these materials.
Supercooling is preventing the application of PCMs in many cases. The project MIKOPUK aims to gain a fundamental knowledge of the relevant physical principles. The project is carried out by the Fraunhofer Insitute for solar Energysystems (ISE) and the Bavarian Center for Applied Energy Research (ZAE Bayern). The project duration is four years.
Project in three phases
In the first year, methods will be developed to encapsulate organic PCMs into different shell materials as well as to emulsify them by using a range of surfactants. In the second year micro encapsulated and emulsified PCM will be produced to investigate the supercooling phenomena. The development of models which will describe the supercooling and crystallization behavior of different material combinations (PCM, capsule, surfactant) will be developed in the third and fourth year of the project.
Microencapsulated and emulsified PCMs are manufactured in this sub-project at ISE. Therfore different combinations of shell and core materials as well as surfactants will be used. After the manufacturing process capsules and emulsions will be charcteriszed by differential scannng calorimetry (DSC) to find correlations between supercooling, size distributions and used materials. At the end a model for the principle of supercooling will be developed.
In this sub-project ZAE Bayern will investigate the cristallisation of the manufactured materials by polarized optical microscopy. This allows to observe the cristalliszation of PCM within single compartments and sizes. In combination with the DSC measurement, this will lead to find better correlations between the characteristics of cristallization, the used materials and the sizes of the compartments.