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In this study, a form-stable composite phase-changing material (PCM) was synthesised by a vacuum impregnation method. Natural Na-bentonite and lauric acid (LA) were used as the supporting material and PCM, respectively. In addition, flake graphite (FG) was used for enhancing the thermal conductivity of the form-stable composite PCM, besides for blocking the leakage of the PCM. Notably, with the addition of FG, the period of melting and freezing of the composite PCM decreased to a certain extend. Meanwhile, the heat-transfer characteristic of the composite increased. Moreover, the as-prepared form-stable composite PCM showed good thermal reliability after 200 cycles of thermal-cold treatment and has the potential to be used in thermal energy storage systems.

This study was aimed at developing a shape-stabilized composite phase-change material (PCM) for thermal energy storage. Raw diatomite was first purified via thermal treatment and acid-leaching to enhance the adsorption capacity of the PCM. The composite PCM was fabricated using myristic acid (MA) to hybridize diatomite via the vacuum impregnation method. Activated carbon (AC) was added to enhance the stability and conductivity of the composite PCM, and it could also be used to prevent the leakage of MA from the supporting materials. The maximum loading capacity and melting enthalpy of MA/H-diatomite-2 reached 72% and 124.3 J g−1, respectively, and its thermal conductivity was as high as 0.58 W (m K)−1. Note that the introduction of AC obviously reduced the melting and freezing periods and enhanced the heat transfer of the composite PCM. Furthermore, MA/H-diatomite-2 exhibits excellent thermal reliability after 200 cycles and could be potentially used in thermal energy storage systems.

This paper aimed to develop a novel form-stable composite phase change material (PCM) by infiltrating molten Na2SO4 into a mullite-corundum porous ceramic preform (M-PCP). Sufficient coal-series kaolinite (Kc), aluminum hydroxide, aluminum fluoride and graphite were mixed and subsequently heated in air at 1450 °C to produce M-PCP. The microstructure, thermal properties and thermal reliability of the composite PCMs were characterized by thermogravimetric and differential scanning calorimetry, X-ray diffraction and scanning electron microscopy. The results indicate that the M-PCP/Na2SO4 was 54.33 J g−1 at its melting temperature of 882.17 °C. Impregnation experiments and numerical simulation demonstrated high-temperature chemical compatibility and wettability between molten Na2SO4 and M-PCP. The M-PCP/Na2SO4 composite showed good thermal stability after 30 thermal shock cycles, and could potentially be used in the thermal energy storage field.

In this paper, novel composite phase change materials (PCMs) were prepared by absorbing stearic acid (SA) into sepiolite (α-sepiolite, β-sepiolite) via a vacuum impregnation method. The microstructures, thermal properties and thermal reliability of the composite PCMs were characterized by SEM, TG and DSC. The results indicate that the maximum SA absorption of α-sepiolite (α-SPL) and β-sepiolite (β-SPL) could reach as high as 60% and 49%. The latent heat of α-SPL/SA and β-SPL/SA were 118.7 J g−1 and 95.8 J g−1, respectively. The thermal cyclic test indicated α-SPL/SA and β-SPL/SA composites have excellent structural stability and thermal reliability. The thermal performance of the composite PCM gypsum boards was also evaluated. The composite PCMs could have a great potential application for thermal energy storage.