Microcalorimetric analysis of granular microencapsulated phase change material including the effects of thermal cycling

• A microcalorimetric test of the encapsulated phase-change material was performed. • Different heating/cooling rates ranging from 1 K·min -1 to 10 K·min -1 were used. • Data on the parameters of the observed phase transition were obtained. • Temperature waveforms runs of the apparent specific heat were obtained. • Attention was paid to the physics of the melting and solidification processes. The subject of the article is the study of granular microcapsules filled with BASF Micronal DS5038 X phase change material (PCM) using thermal analysis methods: thermogravimetry (TG) and microcalorimetry (DSC). The core DSC measurements were performed over a temperature range covering −20 °C to 55 °C or 80 °C, i.e. the area of the two identified, separable ranges of phase change for the filling material. Varying rates of heating/cooling ranging from 1 K·min −1 to 10 K·min −1 were used. The results of the microcalorimetric measurements were supplemented with TG results, ranging from 25 °C to 550 °C. The characterisation of the studied granulate was also complemented by the results of microscopic and profilometric studies documenting the structure of the microcapsules. Based on the results, the enthalpy and temperature of the onset and end of the observed phase changes were determined, as well as representative temperature dependencies of the apparent specific heat were determined – for both heating and cooling processes. The behaviour of the pellets under cyclic forcing of temperature changes with different rates of change was also documented.