Preparation and thermal properties of mineral-supported polyethylene glycol as form-stable composite phase change materials (CPCMs) used in asphalt pavements

Tis work was supported by the National Natural Science Foundation of China (51704040, 51778071, 51608058), the Scientifc Research Project of Hunan Provincial Department of Education for Excellent Young Scholars (16B007), Open Fund of Key Laboratory of Special Environment Road Engineering of Hunan Province (Changsha University of Science & Technology, kf160501), and Open Fund of Key Laboratory of Biohydrometallurgy, Ministry of Education (Central South University, MOEKLB1708)

Thermal and rheological properties of microencapsulated phase change materials

The use of microencapsulated phase change materials (MPCMs) is one of the most efficient ways of storing thermal energy. When the microencapsulated phase change material (MPCM) is dispersed into the carrier fluid, microencapsulated phase change slurry (MPCS) is prepared. Due to the relatively large surface area to volume MPCM and its large apparent specific heat during the phase change period, better heat transfer performance can be achieved. Therefore, MPCS can be used as both the energy storage and heat transfer media. This paper studies the thermal and rheological properties of a series of prepared MPCS. In the experiment: MPCS fabricated by dispersing MPCM into water with an appropriate amount of surfactant. The mass ratio of MPCM to water and surfactant was 10:90:1, 25:75:1, 35:65:1 in prepared MPCS samples, respectively. Then the thermal conductivity and specific heat of MPCS were measured by the Hot Disk. The melting/crystallizing temperature and fusion heat/crystallization heat of the phase change materials were obtained from a DSC (differential scanning calorimetry) during the heating/cooling process. Physical properties, such as viscosity, diameter and its size distribution of MPCS were investigated by a rheometer and a particle characterization system. Meanwhile, the chemical structure of the sample was analyzed using Fourier Transformed Infrared spectroscopy (FTIR). The results showed that the thermal conductivity and the specific heat of MPCS decreased with particle concentration for the temperatures below the melting point. Overall, the MPCS can be considered as Newtonian fluid within the test region (shear rate >200 s−1 and mass fraction <0.35). The viscosity is higher for bigger particle slurries. The findings of the work lead to the conclusion that the present work suggested that MPCMs can be used in “passive” applications or in combination with active cooling systems; and it also provided a new understanding for fabricating microencapsulated phase change slurry, it is for sure that to have a better potential for energy storage. Accordingly, it has demonstrated that the MPCS fabricated in the current research are suitable for potential application as heat transfer media in the thermal energy storage

Capric acid and palmitic acid eutectic mixture applied in building wallboard for latent heat thermal energy storage

470-476The paper aims: (1) preparation of the phase change gypsum wallboard as novel phase change wallboard (PCW) incorporating with the eutectic mixture of capric acid (CA) and palmitic acid (PA) for latent heat thermal energy storage; (2) determination of thermal properties and thermal reliability of prepared PCW using differential scanning calorimetry (DSC) technique; and (3) estimation of thermal performance of PCW by preparing a simple test cell. Maximum CA/PA eutectic mixture as phase change material absorbed in PCW was about 25 wt% of total weight. No leakage of the mixture from PCW was observed after 5000 thermal cycling. The melting and freezing temperatures and latent heats of PCW were measured as 22.94 and 21.66°C, 42.54 and 42.18 J/g, respectively by DSC analysis. These properties make it functional as TES medium, which can be applied to peak load shifting, improved use of waste heat and solar energy as well as more efficient operation of heating and cooling equipment. In addition, PCW has good thermal reliability in terms of the changes in its thermal properties after accelerated 1000, 2000, 3000, 4000, and 5000 thermal cycling. Use of such PCW can decrease indoor air fluctuation and have the function of keeping warmth to improve indoor thermal comfort due to absorption of heat in conjunction with melting of the eutectic mixture

Preparation, characterization and thermal properties of PMMA/n-heptadecane microcapsules as novel solid-liquid microPCM for thermal energy storage

This study is focused on the preparation, characterization and thermal properties of microencapsulated n-heptadecane with polymethylmethacrylate shell. The PMMA/heptadecane microcapsules were synthesized as novel solid-liquid microencapsulated phase change material (microPCMs) by emulsion polymerization method. The chemical and thermal characterization of the microPCMs were investigated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). The diameters of microPCMs were found in the narrow range (0.14-0.40 [mu]m) under the stirring speed of 2000 rpm. The spherical surfaces of microPCMs were smooth and compact. The DSC results show that microPCMs have good energy storage capacity. Thermal cycling test showed that the microPCMs have good thermal reliability with respect to the changes in their thermal properties after repeated 5000 thermal cycling. TGA analyses also indicated that the microPCMs degraded in three steps and have good thermal stability. Based on all results, it can be considered that the PMMA/heptadecane microcapsules as novel solid-liquid microPCMs have good energy storage potential.n-Heptadecane PMMA MicroPCM Thermal properties Energy storage