Sustainable Cities and Society
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2018
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IF 3.073
Li Yang,Xiaoling Cao,Nan Zhang,Bo Xiang,Zhaoli Zhang,Bin Qian
The thermal reliability of phase change materials (PCMs) is an important factor for the successful application of latent heat thermal energy storage. In this work, 10,000 thermal cycles have been firstly carried out to investigate the thermal reliability of four typical fatty acids (lauric acid, myristic acid, palmitic acid and stearic acid) as PCMs. The thermal properties before and after cycles were tested by differential scanning calorimeter. It was found that with increasing number of thermal cycles, both the phase transition temperature and the latent heat tended to decrease. In the experiment, the maximum change in the melting temperature was −0.37 °C and change rate of latent heat was −7.57%. The freezing temperature decreased obviously with increasing number of thermal cycles, which led to a maximum increase of 4.15 °C in the degree of supercooling. In addition, the specific heat and thermal conductivity of the PCMs after 10,000 thermal cycles had no significant change. FT-IR showed that the chemical structure of fatty acids had not changed after thermal cycles. The experimental results showed that these fatty acids can function as admirable PCMs with high thermal reliability for long-term applications.
研究领域:
材料科学
·
热能工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Energy Storage
·
2025
·
IF 9.8
Zhiheng Pan,Maoyong Zhi,Huajian Cui,Qinrou Xu,Qiang Sun,Quanyi Liu
Novel eutectic-MEG phase change material (PCM) was prepared by physical blend methods using sodium acetate trihydrate, glycine, disodium hydrogen phosphate dodecahydrate, and hydrophilic modified expanded graphite (MEG). The eutectic-MEG was introduced into silicone rubber to prepare the low-cost and shape-stable composite PCM (SSPCM). SEM analysis showed that the dispersion of the eutectic-MEG mixture was homogeneous in the SSPCMs. The flexibility of SSPCM improved with the increased amount of silicone rubber. Additionally, the thermal cycle and anti-leakage experiments suggested that SSPCM possessed good thermal reliability. SSPCM-55 showed an enthalpy value of 128.1 J/g, melting temperature of 48.36 °C, thermal conductivity of 0.81 W/(m·K), subcooling degree of 2.7 °C, only 2.7 % enthalpy loss after 100 heating and cooling cycles, and leakage rates of 2.65 %. The limiting oxygen index (LOI) values of all the SSPCMs were above 90 %, and they passed the UL-94 test with a V-0 rating. In addition, as the content of hydrated salts increased, the capacity of phase change thermal storage was significantly improved. This study provides beneficial ideas for the preparation of multifunctional PCMs in building energy conservation and thermal management of electronic products.
研究领域:
材料科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2021
·
IF 6.141
Zhaolin Li,Junjie Yuan
This study reports the preparation of phase change microcapsules (PCMs) which possess high encapsulation efficiency, this is achieved by using Janus silica particles (JSPs) as stabilizers in combination with Pickering emulsion and suspension polymerization methods. The inner shell and outer shell of the PCMs are polyacrylate and JSPs respectively. The morphologies and particle sizes of the PCMs can be controlled well, as evidenced by SEM and optical microscopy characterization. The amount of JSPs and functional monomer methacrylic acid play key roles in controlling the morphologies of the PCMs. The encapsulation ratio of PCMs can be adjusted with the encapsulation efficiency reaching as high as 99.6%. The phase change enthalpy of the PCMs is 175.1 J/g when the core/inner shell/outer shell weight ratio of n-octadecane/polyacrylate/silica microcapsules is 70:21:1. The TGA result indicates that the PCM is stable up to 150 °C. The enthalpy of PCM remains almost unchanged after 7560 phase change cycles, illustrating the PCM exhibits excellent thermal reliability and durability. The PCM-modified cement plate shows a remarkable cooling effect, which means that this type of PCM has promising applications in the construction field.
研究领域:
材料科学
·
建筑技术
✓ 已验证
DOI
高影响因子
APPLIED ENERGY
·
2020
·
IF 8.848
Lijuan He,Songping Mo,Pengcheng Lin,Lisi Jia,Ying Chen,Zhengdong Cheng
Sugar alcohols have considerable potential for usage in medium-temperature thermal energy storage applications; however, they suffer from poor thermal reliability and low thermal conductivity . Nanoencapsulation is an effective approach to improve the thermal energy storage performance of the phase-change materials. Until now, nanoencapsulation of sugar alcohols with a high phase-change performance has been rarely reported. The objective of this study is to develop a method for the nanoencapsulation of sugar alcohols with an enhanced phase-change performance. D-mannitol nanocapsules with a silica–graphene oxide composite shell were synthesized and investigated to demonstrate the validity of this novel method. The morphology, size distribution, and core–shell microstructure of the nanocapsules were observed using a scanning electron microscope, particle size and zeta potential analyzer, and transmission electron microscope. In addition, the phase-change performance of the nanocapsules was studied using a differential scanning calorimeter, a thermogravimetric analyzer, and weight loss and appearance investigation. The results demonstrate that the melting and solidifying latent heat of the nanocapsules are 216.7 and 174.4 kJ/kg, respectively. The energy storage efficiency of the nanocapsules was 75.8% and its 96.1% was maintained after repeated thermal cycling. Compared with pure D-mannitol, the thermal conductivity of the nanocapsules was observed to increase by up to 128.6%. The novel nanocapsules exhibited good medium-temperature thermal energy storage prospects.
研究领域:
材料科学
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能源存储
·
纳米技术
✓ 已验证
DOI
高影响因子
ENERGY
·
2017
·
IF 4.52
Rui-rui Cao,Xuan Li,Sai Chen,Hao-ran Yuan,Xing-xiang Zhang
A series of a novel shape-stabilized phase change material of poly(hexadecyl acrylate)/graphene oxide (PHDA/GO) nanocomposite was fabricated by in situ free radical polymerization . The fabricated PHDA/GO nanocomposites mainly contain a poly(hexadecyl acrylate)-grated-graphene oxide (PHDA- g -GO) solid-solid phase change material (SSPCM) and a PHDA solid-liquid phase change material (SLPCM). The PHDA- g -GO SSPCM plays two roles in the PHDA/GO nanocomposites: as the supporting material and as a phase change working substance. The effects of GO loading on the crystalline properties and the phase change properties of the PHDA/GO nanocomposites were investigated. The results indicate that the grain size of the PHDA/GO nanocomposites increases with GO loading. The nanocomposites have high thermal enthalpies, and their enthalpy efficiencies are significantly higher than those of traditional shape-stabilized PCMs (TPCMs) because of the synergistic phase change effect of PHDA- g -GO and PHDA. The number of crystalline CH 2 groups, including the terminal methyl, in the alkyl side chain of PHDA increases from 6.42 to 8.82. Moreover, the FTIR spectra and DSC curves of the PHDA/GO nanocomposites after thermal cycles are nearly the same as those of the original specimens , which indicate that the nanocomposites have excellent thermal reliability and reusability . This study not only provides a kind of novel shape-stabilized PCM with a high performance but also proposes a new way to solve the problem of enthalpy decline observed in TPCMs.
研究领域:
材料科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
SOLAR ENERGY MATERIALS AND SOLAR CELLS
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2017
·
IF 4.784
Ziye Ling,Junwan Liu,Qianhao Wang,Wenzhu Lin,Xiaoming Fang,Zhengguo Zhang
MgCl 2 ·6H 2 O-Mg(NO 3 ) 2 ·6H 2 O eutectic has a proper melting point and high latent heat for solar water heating systems with latent heat storage . In this paper, the exact composition of the eutectic and the corresponding phase change temperature are determined by measuring the phase change characteristics of mixtures of MgCl 2 ·6H 2 O and Mg(NO 3 ) 2 ·6H 2 O in various ratios. MgCl 2 ·6H 2 O-Mg(NO 3 ) 2 ·6H 2 O eutectics, the melting temperature of which is around 58 °C, can be obtained with the mass fraction of MgCl 2 ·6H 2 O ranging from 35% to 50%. The eutectics are composited with porous fumed silica to improve its thermo-physical properties. The eutectic/SiO 2 composite retains a similar melting point of the pure eutectic, is of no liquid leakage even after melting while the SiO 2 weighs more than 15 wt%, and the specific enthalpy reaches 88.13 kJ kg −1 . The eutectic/SiO 2 composite has a thermal conductivity 5% higher than pure eutectics and better thermal stability and cycle stability. The thermogravimetric analysis shows its weight loss is 8.03% less than pure eutectic at 300 °C. And the eutectics suffers a decrease in phase change enthalpy after 100 thermal cycles by 9.2%, much lower compared with the 37.23% for pure eutectics due to the phase separation during the thermal cycles. Thermo-physical properties and stability of MgCl 2 ·6H 2 O-Mg(NO 3 ) 2 ·6H 2 O eutectic have been enhanced by fumed silica.
研究领域:
材料科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
PROGRESS IN ORGANIC COATINGS
·
2020
·
IF 4.469
Dechao Hu,Zhiqiang Wang,Wenshi Ma
Microencapsulated phase change materials (MEPCMs) can efficiently prevent the leakage and erosion of melting phase change materials during phase change process, which exhibit a bright industrial application prospect in the fields of thermal energy storage. Herein, a novel polyurethane (PU) microencapsulated methyl laurate was successfully fabricated via interfacial polymerization. The preparation conditions of PU-based MEPCMs were comprehensively explored, offering a systematic guidance for the tailored design of novel MEPCMs. And the experimental results indicate that the obtained PU-based MEPCMs have high latent heat storage capacity. Specially, when the core/shell mass ratio is 3:1, the melting enthalpies, freezing enthalpies, and core contents of MEPCMs reach as high as 136.2 J/g, 121.2 J/g and 75.18 %, respectively. Meantime, the resulting PU-based MEPCMs also present excellent thermal reliability and storage stability. The development of novel PU-based MEPCMs may open up a new opportunity for their wider applications in the thermal energy storage fields such as architectural coatings, refrigerated storage, and functional thermal fluids.
研究领域:
材料科学
·
热能工程
·
能量存储
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）