Effect of fumed silica additive on supercooling, thermal reliability and thermal stability of Na2HPO4·12H2O as inorganic PCM

A novel phase change materials (PCMs) composite was fabricated by sol-gel method for cold energy storage. Methyl laurate (ML) as cold energy medium was preferred due to its appropriate phase change temperature (3.96 ℃) and high latent heat (210.1 J/g), and silica provided a complete external protection for the ML. Various techniques were used to characterize the as-prepared ML/SiO2 PCMs composite so as to investigate its structure and thermal properties, including scanning electron microscopy (SEM), fourier transforms infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA). During the PCMs composite forming process, hydrogen bonds generated by the interaction of carboxyl group of ML, the silicon hydroxyl group of silica, and the hydroxyl groups of emulsifier PVA promoted the morphology change of the PCMs composite from sphere-like to net-like structure. The DSC results showed that the net-like PCMs melted at 6.71 ℃ with a latent heat of 151.3 J/g and solidified at -5.43 ℃ with a latent heat of 148.9 J/g. Besides, the PCMs composite exhibited outstanding chemical compatibility, thermal reliability and complete micromorphology. Thus, the prepared ML/SiO2 PCMs composite with novel net-like structure had great potential for cold energy storage.

Thermal characterization of net-like and form-stable ML/SiO2 composite as novel PCM for cold energy storage

Design and synthesis study of the thermo-sensitive copolymer carrier of penicillin G acylase

Ammonium alum hydrate slurries with surfactants and polyvinyl alcohol as a latent heat transportation material for high temperature

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Structural and kinematic analysis of a stirred tank planetary drive

The fabrication method of silica hard shell microcapsules containing disodium hydrogen phosphate dodecahydrate (Na 2 HPO 4 ⋅12H 2 O) has been developed. The effects of the mixing rates for the emulsification, of the volume ratios of solutions and of surfactant concentrations on the size of hollow microcapsules have been also studied. From the results, it was confirmed that silica hard shell microcapsules can contains Na 2 HPO 4 ⋅12H 2 O with the present method using hollow microcapsules. The present micro-encapsulated Na 2 HPO 4 ⋅12H 2 O was also found to cause the supercooling depression effect. As the fabricated microcapsules have no flammability, the present microcapsule was concluded to be a promising item not only for latent heat transportation media but also for the static thermal storage materials for architectural structures. From the studies on the fabrication parameters, it was concluded that the control of the surfactant concentration is effective for controlling the size of microcapsule.

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Fabrication of hard-shell microcapsules containing inorganic materials

Application of a Rotationally Reciprocating Plate Impeller on Crystallization Process

The effect of shearing conditions in the coating process on the uniformity of the coated layer of dense silica slurry is investigated. The pH 6.8 test slurry mainly used in this study forms a nonuniform coated layer only on the condition of large shear strain and low shear rate. The same shearing dependency was observed using not only a laboratory-scale doctor blade but also a pilot-scale comma coater. The test slurry exhibits two-step yielding, and the internal structure of the slurry is gradually destroyed after the second yielding. When the shear strain applied is within the second yielding, the test slurry is in equilibrium and a uniform coated layer is formed. As strain is increased further, the slurry changes from the viscoelastic fluid to Newtonian. When the shear strain is beyond the second yielding but the structural destruction is not completed, a nonuniform coated layer is formed. A higher coating speed or sufficiently large shear deformation, which effectively destroys the internal structure, is favorable to obtain a uniform coated layer.

Kosuke Suzuki

Papers

Fabrication of hard-shell microcapsules containing inorganic materials

Application of a Rotationally Reciprocating Plate Impeller on Crystallization Process

The effect of yielding of dense silica slurry on the uniformity of coated layer

Forced Motion of a Single Particle in Micron-sized Particle Dispersion

Effects of Drying Rate and Slurry Microstructure on the Formation Process of Lib Cathode and Electrochemical Properties