Rubber - Phase Change Material Composites for Heat Storage Applications
Ruokangas, Sasu (2018)
Ruokangas, Sasu
2018
Materiaalitekniikka
Teknisten tieteiden tiedekunta - Faculty of Engineering Sciences
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Hyväksymispäivämäärä
2018-01-10
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201712182397
https://urn.fi/URN:NBN:fi:tty-201712182397
Tiivistelmä
Because of the universal concern over accelerated climate change and increasing price of fossil fuels, renewable energy sources and energy efficiency has become more and more important. These both make use of heat storage. Heat can be stored by either sensible heat or latent heat, of which latent heat offers multiple heat storage capacity. The materials that can store or release large amounts of heat during a phase change are called phase change materials (PCM). The majority of PCMs are so-called solid-liquid phase change materials. For practical applications, the leakage of the PCMs at their liquid phase must be prevented. The most cost-efficient way to do this is to disperse the PCM in a matrix material. This kind of composites are called shape stabilized phase change materials (SSPCM).
The main goal of the theory part of this thesis was to research previous studies concerning SSPCMs with polymeric matrix. The understanding of these previous studies was important in order to provide the scope and reference to the experimental part of this thesis. The purpose was to figure out the used matrix materials, phase change materials as well as the most important properties of different material combinations. The most important properties of SSPCMs are the phase change temperature and the latent heat, as they determine the application temperature and heat storage capacity of the material. Another important thermal property is thermal conductivity, which influences the heat transfer between the SSPCM and the environment, thus restricting the efficiency of the heat storage. These previous studies were important to provide the scope and reference to the experimental part of this thesis. Besides thermal properties, mechanical properties such as tensile strength and elasticity are important in certain applications.
The aim of the experimental part of this thesis was to prepare SSPCMs with NR and latex matrixes, to study their properties and to find the most compatible PCM/matrix combinations and optimal PCM contents. It was found that the heat storage capacity of the SSPCMs increases with increasing PCM content. By contrast, mechanical properties deteriorate when PCM content is increased. Thus, the PCM content of the SSPCM should be optimized according to the requirements of the application. In this study, an optimal PCM content to offer sufficient heat storage capacity while still retaining satisfactory mechanical properties was found to be 50 phr (parts per hundred rubber). Paraffins were found to be the most compatible PCM group to be mixed with rubber, as they maintained their heat storage capacity more effectively than other options. Moreover, paraffins did not seem to change the mechanical properties of rubber as much as other PCMs.
The main goal of the theory part of this thesis was to research previous studies concerning SSPCMs with polymeric matrix. The understanding of these previous studies was important in order to provide the scope and reference to the experimental part of this thesis. The purpose was to figure out the used matrix materials, phase change materials as well as the most important properties of different material combinations. The most important properties of SSPCMs are the phase change temperature and the latent heat, as they determine the application temperature and heat storage capacity of the material. Another important thermal property is thermal conductivity, which influences the heat transfer between the SSPCM and the environment, thus restricting the efficiency of the heat storage. These previous studies were important to provide the scope and reference to the experimental part of this thesis. Besides thermal properties, mechanical properties such as tensile strength and elasticity are important in certain applications.
The aim of the experimental part of this thesis was to prepare SSPCMs with NR and latex matrixes, to study their properties and to find the most compatible PCM/matrix combinations and optimal PCM contents. It was found that the heat storage capacity of the SSPCMs increases with increasing PCM content. By contrast, mechanical properties deteriorate when PCM content is increased. Thus, the PCM content of the SSPCM should be optimized according to the requirements of the application. In this study, an optimal PCM content to offer sufficient heat storage capacity while still retaining satisfactory mechanical properties was found to be 50 phr (parts per hundred rubber). Paraffins were found to be the most compatible PCM group to be mixed with rubber, as they maintained their heat storage capacity more effectively than other options. Moreover, paraffins did not seem to change the mechanical properties of rubber as much as other PCMs.