Abstract:Summary
In this work, diatomite (DM) was calcined at 400°C to obtain the pure surface and pores (DM‐1); then, the three kinds of shape‐stable composite phase change materials (ss‐CPCMs) of CaCl2·6H2O (CCH)/DM‐1, CH3COONa·3H2O (SAT)/DM‐1, and Na2SO4·10H2O (SSD)/DM‐1 were prepared by impregnation method. The hydrated salts were uniformly adsorbed on the surfaces and into the pores of DM‐1 by capillary action and surface tension. The addition of nucleating agent effectively reduced the supercooling degrees of hyd… Show more
“…The sample with the 70% loading demonstrated stable phase transition temperature after 1000 thermal cycles, yet the LHS capacity reduced to 163.1 J/g due to the mass loss of about 2.2 wt%. Yang et al reported on the preparation of hydrated salt/diatomite composites with reduced supercooling and enhanced thermal conductivity [104]. The three types of composites were prepared by mechanical impregnation of CaCl 2 •6H 2 O, CH 3 COONa•3H 2 O, and Na 2 SO 4 •10H 2 O into diatomite particles.…”
The development of novel materials and approaches for effective energy consumption and the employment of renewable energy sources is one of the current trends in modern material science. With this respect, the number of researches is focused on the effective harvesting and storage of solar energy for various applications. Phase change materials (PCMs) are known to be able to store thermal energy of the sunlight due to adsorption and release of latent heat through reversible phase transitions. Therefore, PCMs are promising as functional additives to construction materials and paints for advanced thermoregulation in building and industry. However, bare PCMs have limited practical applications. Organic PCMs like paraffins suffer from material leakage when undergoing in a liquid state while inorganic ones like salt hydrates lack long-term stability after multiple phase transitions. To avoid this, the loading of PCMs in porous matrices are intensively studied along with the thermal properties of the resulted composites. The loading of PCMs in microcontainers of natural porous or layered clay materials appears as a simple and cost-effective method of encapsulation significantly improving the shape and cyclic stability of PCMs. Additionally, the inclusion of functional clay containers into construction materials allows for improving their mechanical and flame-retardant properties. This article summarizes the recent progress in the preparation of composites based on PCM-loaded clay microcontainers along with their future perspectives as functional additives in thermo-regulating materials.
“…The sample with the 70% loading demonstrated stable phase transition temperature after 1000 thermal cycles, yet the LHS capacity reduced to 163.1 J/g due to the mass loss of about 2.2 wt%. Yang et al reported on the preparation of hydrated salt/diatomite composites with reduced supercooling and enhanced thermal conductivity [104]. The three types of composites were prepared by mechanical impregnation of CaCl 2 •6H 2 O, CH 3 COONa•3H 2 O, and Na 2 SO 4 •10H 2 O into diatomite particles.…”
The development of novel materials and approaches for effective energy consumption and the employment of renewable energy sources is one of the current trends in modern material science. With this respect, the number of researches is focused on the effective harvesting and storage of solar energy for various applications. Phase change materials (PCMs) are known to be able to store thermal energy of the sunlight due to adsorption and release of latent heat through reversible phase transitions. Therefore, PCMs are promising as functional additives to construction materials and paints for advanced thermoregulation in building and industry. However, bare PCMs have limited practical applications. Organic PCMs like paraffins suffer from material leakage when undergoing in a liquid state while inorganic ones like salt hydrates lack long-term stability after multiple phase transitions. To avoid this, the loading of PCMs in porous matrices are intensively studied along with the thermal properties of the resulted composites. The loading of PCMs in microcontainers of natural porous or layered clay materials appears as a simple and cost-effective method of encapsulation significantly improving the shape and cyclic stability of PCMs. Additionally, the inclusion of functional clay containers into construction materials allows for improving their mechanical and flame-retardant properties. This article summarizes the recent progress in the preparation of composites based on PCM-loaded clay microcontainers along with their future perspectives as functional additives in thermo-regulating materials.
“…At present, many researchers pay more attention to the improvement of thermal conductivity and supercooling suppression. − However, while solving the above problems (add additives), the corresponding heat storage capacity will decrease. − How to further improve the packaging performance is of great significance to the energy storage application of composite PCMs. In recent years, pore minerals have been studied extensively, and expanded vermiculite (EVM) has become a typical representative material with its unique layered pore structure, high porosity, and large pore volume.…”
In
this study, the optimized expanded vermiculite (EVM) was used
as the matrix and a series of novel form-stable composite phase change
materials (fs-CPCMs) were prepared by the physical impregnation method.
The results showed that acid leaching and organic intercalation EVM
had a better package effect (≥74.9 wt %) and heat storage capacity
(≥139.2 J/g) compared with EVM, which showed a good optimization
effect, revealing that proper modification treatment was beneficial
to the improvement of the thermophysical properties of composite PCMs.
Nonisothermal crystallization kinetics demonstrated that the EVM matrix
was beneficial to reduce the nucleation activation energy (ΔE
a) of PEG, and the optimized EVM could further
reduce the ΔE
a, which effectively
improved the crystal nucleation process of PEG. However, the matrix
would restrict the crystal growth process of PEG, which had certain
adverse effects. Moreover, XRD, TGA, and cycle tests showed that the
prepared novel fs-CPCMs had excellent chemical stability, thermal
stability, and cycle reliability. This research provided a certain
theoretical reference and technical support for the preparation of
mineral-based organic composite phase change materials with high heat
storage capacity and excellent phase change behavior.
“…Moreover, sugar alcohols exhibit ultra-high and unstable supercooling and low thermal conductivity, which are seriously adverse to their application. [4][5][6] Form-stable PCMs, in which traditional solid-liquid PCMs are confined in the inner spaces of supporting materials, can solve the problem of possible leakage of liquid PCMs. 7 The thermal energy is stored by the solidliquid PCMs, while the supporting materials maintain the solid shape of the form-stable PCMs.…”
Section: Introductionmentioning
confidence: 99%
“…7 The thermal energy is stored by the solidliquid PCMs, while the supporting materials maintain the solid shape of the form-stable PCMs. The supporting materials for form-stable PCMs can be ether inorganics such as diatomite, 6 SiO 2,8 TiO 2 9 and fly ash, 10 etc., or polymers such as polymethyl methacrylate, 11 polyurethane, 12 resin, 13 and polyaniline (PANI), 14,15 etc. Graphite-based materials are another kind of important supporting materials.…”
Section: Introductionmentioning
confidence: 99%
“…The supporting materials for form-stable PCMs can be ether inorganics such as diatomite, 6 SiO 2, 8 TiO 2 9 and fly ash, 10 etc., or polymers such as polymethyl methacrylate, 11 polyurethane, 12 resin, 13 and polyaniline (PANI), 14,15 etc. The supporting materials for form-stable PCMs can be ether inorganics such as diatomite, 6 SiO 2, 8 TiO 2 9 and fly ash, 10 etc., or polymers such as polymethyl methacrylate, 11 polyurethane, 12 resin, 13 and polyaniline (PANI), 14,15 etc.…”
Summary
Sugar alcohols are promising solid‐liquid phase change materials (PCMs). However, problems such as possible leakage of liquid PCMs, high and unstable supercooling, and low thermal conductivity need to be solved. In this work, a novel form‐stable PCM in which m‐erythritol (ME), polyaniline (PANI), and silver nanowires (Ag NWs) were applied as solid‐liquid PCM, supporting material, and thermal conductive filler, respectively, was successfully prepared in anhydrous ethanol by surface polymerization of aniline. Form‐stable PCM with good form stability could be obtained when the ratio of ME/(aniline + ME) was no more than 78.7 wt%. The melting enthalpy (ΔHm) of the ME/PANI form‐stable PCMs could attain 234.8 J/g while that of the ME/PANI/Ag NWs form‐stable PCMs was about 220 J/g. In addition, the thermal conductivity of the form‐stable PCM was increased by 61.6% when 7.5 wt% Ag NW was added. Moreover, the supercooling of ME was effectively suppressed from 100°C for pure ME to 60°C, corresponding to an improvement of 40%, for the form‐stable PCM containing 7.5 wt% Ag NWs. The supercooling suppression could be ascribed to that PANI provided great amounts of nucleating centers and improved the nucleation kinetics, and Ag NWs improved the thermal diffusivity and thus increased the crystallization rate.
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