Mahyar Silakhori

Accelerated Thermal Cycling Test of Microencapsulated Paraffin Wax/Polyaniline Made by Simple Preparation Method for Solar Thermal Energy Storage

Microencapsulated paraffin wax/polyaniline was prepared using a simple in situ polymerization technique, and its performance characteristics were investigated. Weight losses of samples were determined by Thermal Gravimetry Analysis (TGA). The microencapsulated samples with 23% and 49% paraffin showed less decomposition after 330 °C than with higher percentage of paraffin. These samples were then subjected to a thermal cycling test. Thermal properties of microencapsulated paraffin wax were evaluated by Differential Scanning Calorimeter (DSC). Structure stability and compatibility of core and coating materials were also tested by Fourier transform infrared spectrophotometer (FTIR), and the surface morphology of the samples are shown by Field Emission Scanning Electron Microscopy (FESEM). It has been found that the microencapsulated paraffin waxes show little change in the latent heat of fusion and melting temperature after one thousand thermal recycles. Besides, the chemical characteristics and structural profile remained constant after one thousand thermal cycling tests. Therefore, microencapsulated paraffin wax/polyaniline is a stable material that can be used for thermal energy storage systems.

Preparation and characterisation of microencapsulated paraffin wax with polyaniline-based polymer shells for thermal energy storage

Abstract Microencapsulated paraffin wax with polyaniline shells is synthesised as thermal energy storage material by in situ polymerisation. Paraffin wax is the core material and polyaniline is the shell in this preparation. These materials are environment-friendly. The chemical structure, surface morphologies, thermal properties and thermal stability of the encapsulated paraffin wax are determined by Fourier transform infrared spectrophotometry, field-emission scanning electron microscopy, differential scanning calorimeter and thermogravimetry analysis, respectively. The field-emission scanning electron microscopic results indicate that the paraffin wax is encapsulated well and that the capsules are spherical in shape. The differential scanning calorimetric analysis shows that the encapsulated paraffin wax has a large energy storage and releases capacity (22–121 J g−1) depending on the different ratios of the paraffin wax and polyaniline. The thermogravimetric analysis results indicate that polyaniline can improve the thermal stability of encapsulated paraffin wax because of the synergistic effect between the two (paraffin wax and polyaniline). Based on these results, it can be concluded that the microencapsulated paraffin wax that acts as a microencapsulated phase change material has a good potential for thermal energy storage purposes.

Investigation of Thermal Characteristic of Eutectic Fatty Acid/Damar Gum as a Composite Phase Change Material (CPCM)

A composite phase change material (CPCM) of myristic acid/palmitic acid/sodium myristate (MA/PA/SM) has been proposed by impregnating a porous material of purified damar gum, also called Shorea javanica (SJ), to improve the thermal conductivity of CPCM. The thermal properties, thermal conductivity and thermal stability, of CPCM were measured using differential scanning calorimetry (DSC) thermal analysis, hot-disc thermal conductivity analyzer, and simultaneous thermal analyzer (STA). Moreover, a chemical reaction between fatty acid binary mixture and SJ in CPCM was evaluated by Fourier transform infra-red (FT-IR) spectrophotometer. The results of this study showed that the thermal conductivity of MA/PA/SM/SJ composite phase change material (CPCM) was improved by addition of 3 wt.% of Shorea javanica into MA/PA/SM eutectic mixture without showing a significant change in the thermophysical properties of CPCM. Moreover, the eutectic CPCM also does not show occurrence of chemical reaction between MA/PA/SM and SJ, and it has a good thermal performance and thermal stability. Therefore, the MA/PA/SM/SJ CPCM proposed in this study can be recommended as a new novelty material for thermal energy storage application.