Apparent thermal properties of phase-change materials: an analysis using differential scanning calorimetry and transient impulse method

Z. Pavlík1, A. Trník2, M. Keppert1, M. Pavlíková1, P. Volfová1 and R. Černý1

1Czech Technical University in Prague, Czech Republic
2Constantine the Philosopher University, Slovakia

Keywords: phase-change materials, DSC, transient impulse technique
property: thermal conductivity, specific heat capacity
material: lime-based plaster, parafinnic wax

Application of latent heat storage building envelope systems using phase change materials (PCMs) represents an effective way of storing thermal energy and has the advantages of high-energy storage density and the isothermal nature of the storage process. Since the benefit of PCMs for indoor environment quality of buildings was already proved, there is a need to develop and test new building materials with PCMs and design them for specific applications in building industry. Probably the lowest heat storage capacity exhibit the lightweight building envelope systems. On that account, the newly developed light weight plaster that should enhanced the heat storage capacity of light weight systems of building envelopes is studied in the paper. This material is based on hydrated lime as main binder and the durability of this material is enhanced by metakaoline addition. Into the dry mixture, the Micronal PCM is added for the improvement of heat storage capacity. Within the performed experiments, measurement of basic material properties of studied material was done at first. The measurements were first performed on Micronal PCM capsules only. For the capsules, bulk density, matrix density and grain-size curve were measured, whereas the grain-size distribution was accessed using laser diffraction method. For the developed plaster, there were measured bulk density, matrix density, total open porosity, and pore size distribution. Then, the detailed investigation of its thermal properties was performed. Difference scanning calorimetry (DSC) was firstly applied on Micronal PCM capsules for determination of temperature interval of thawing and latent heat of phase change. Then, the DSC was applied on the developed plaster and initial temperature of phase change and its latent heat were determined. For these measurements, Mettler-Toledo DSC 822e was used. Thermal conductivity thermal and diffusivity were measured by transient pulse method using apparatus ISOMET 2104. For the comparative reasons, the investigation of lime based plaster without PCM application was done as well. The obtained results revealed the temperature dependence of the measured thermal properties and proved the enhanced heat storage capacity of studied material that can be used for application in lightweight building envelope systems. This work has been financially supported by the Ministry of Education, Youth and Sports of Czech Republic, under project No MSM: 6840770031.

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