APPLIED ENERGY
·
2014
·
IF 5.261
Xing Li,Ying Chen,Zhengdong Cheng,Lisi Jia,Songping Mo,Zhuowei Liu
Graphene is widely utilized because of its exceptional properties, such as strong mechanical strength, low weight, nearly optical transparency, and excellent conductivity of heat and electricity. In this study, we used the ultrahigh specific surface area of graphene due to its inherently two-dimensional nature to reduce the subcooling of freezing of a phase change material. The results enable graphene’s application in energy storage using the latent heat of phase transition. The need for subcooling to freeze water was eliminated completely with the suspension of a very low mass fraction (0.020 ± 0.001 wt%) or surface area concentration (0.070 ± 0.003 m 2 /ml) of graphene. Compared to nanoparticles of SiO 2 and TiO 2 with the same mass fraction suspended in water, flakes of graphene led to freeze water at a much smaller subcooling degree, and shorter total freezing time. The addition of surfactants can improve suspension stability and further reduce the degree of subcooling, but it also slightly increases the total freezing time. Graphene flakes are more suitable than spherical oxide nanoparticles for use as nucleating additives in water.
研究领域:
材料科学
·
能源存储
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Yidong Hu,Fan Yang,Guoliang Ren,Jianguo Li,Qiaodan Hu
Preparation of dense Bi 2 Ti 2 O 7 ceramics with single-phase pyrochlore structure is challenging using the conventional sintering method due to its thermal instability at ≥ 650 °C. Here we synthesized dense and phase-pure Bi 2 Ti 2 O 7 ceramics from a mixture of Bi 2 O 3 and TiO 2 by a novel deep undercooling rapid solidification method using the aerodynamic levitation technique. We reported a surprising discovery that the pyrochlore phase can exist with Bi/Ti ratio varying between 0.9 and 1.1. By a comprehensive investigation on the phase purity, crystal structure, oxidation states and electrical properties, we revealed that the pyrochlore structure is primarily stabilized by the solidification process rather than presence of a large amount of Ti 3+ . With the advantages of being containerless, one-step and fast processing, deep undercooling rapid solidification is an effective and efficient approach to prepare dense Bi 2 Ti 2 O 7 pyrochlores, and can be expanded to other thermally unstable compounds to obtain bulk materials.
研究领域:
材料科学
·
无机化学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Weiye Chen,Lei Chen,Liangyu Li,Chuanshuai Dong,Lizhi Zhang
Phase change energy storage technology has broad applications in many engineering fields, such as building energy conservation, aerospace, and thermal management of electric equipment. However, the inorganic phase change materials suffer a lot from supercooling, phase separation, and low thermal conductivity. Therefore, this paper aims at developing a novel electrically-triggered phase change composite by making use of its supercooling characteristics, achieving a controllable release of latent heat as it is wanted. Polished by radial and axial grinding respectively, both surface-triggered electrodes (STE) with a uniform rough structure and point-triggered electrodes (PTE) with the gradient rough structure were prepared to investigate the effect of surface structure on the electrical crystallization. The 100-cycle test results indicated the newly-prepared electrode achieved a stable electrically-triggering ability. The oxidation rate of electrodes was significantly affected by interface characteristics of the gas–liquid-solid interfaces. What’s more, the effect of voltage and supercooling degree on the crystallization behaviours, like induction time, morphology, and growth of the dendrite, and heat transfer process, were comprehensively investigated. With the increase of the supercooling degree, the dendrite shape gradually changed from acicular crystal to flocculent crystal, and the induction time decreased rapidly. To improve the thermal conductivity, a novel phase change composite using sodium acetate trihydrate/carboxymethyl cellulose/expanded graphite (SAT/CMC/EG) was developed. Considering both thermal conductivity and electrical nucleation, the optimized mass ratio of SAT: CMC: EG was 100:1:8. These research findings would provide valuable guidance in the intelligently-controllable energy storage technology.
研究领域:
材料科学
·
能源存储技术
✓ 已验证
产品关联
DOI
高影响因子
SOLAR ENERGY MATERIALS AND SOLAR CELLS
·
2024
·
IF 6.3
Yeke Chenxu,Xuefeng Shao,Binrui Wang,Nan Zhang,Yanping Yuan
Towards long-term seasonal latent heat storage, the PCMs with strong supercooling are recommended as the heat storage medium. Nevertheless, the suitable techniques activating latent heat release is also of significance in the period of heat supply. The present work investigated the N 2 bubbling triggered crystallization of supercooled xylitol. Special attention was paid to the subcooling effect. The N 2 bubbling was identified to be a potential technique to trigger crystallization of xylitol at moderate degrees of subcooling. It was found that efficient crystallization issues were obtained with degrees of subcooling from 40 °C to 60 °C, while uncrystallization was obtained with both lower and higher subcooling. The recorded temperature history curves show that subcooling effect has strong influence on the crystallization behavior. The crystallization points tend to decline from 51.9 °C to 42.3 °C with degree of subcooling rising from 40 °C to 50 °C. The crystallization durations extend with subcooling effect enhancing. Fortunately, bubbling technique has slight influence on the properties of formed xylitol crystals. Moreover, the subcooling significantly influences the transportation behavior of bubbles. Particularly, The specific growth rates of bubbles are determined to be as low as 0.005 mm/min with the lowest degree of subcooling 10 °C, and continue to rise over 20 times when the subcooling reaches to 60 °C. The interfaces of bubbles as potential nucleation sites were deemed to be one of the important issues to activate heterogeneous nucleation, thus trigger crystallization. The present investigation is helpful to understand the fundamentals of bubbling effect on crystallization with broad range of subcooling.
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
Nanoscale Research Letters
·
2018
·Vol. 13
·期 1
·1-10
·
IF 3.125
Cui Wei,Jia Lisi,Chen Ying,Li Yi’ang,Li Jun,Mo Songping
Nanoparticles, including Al 2 O 3 and SiO 2 , and ultrasound were adopted to improve the solidification properties of water. The effects of nanoparticle concentration, contact angle, and ultrasonic intensity on the supercooling degree of water were investigated, as well as the dispersion stability of nanoparticles in water during solidification. Experimental results show that the supercooling degree of water is reduced under the combined effect of ultrasound and nanoparticles. Consequently, the reduction of supercooling degree increases with the increase of ultrasonic intensity and nanoparticle concentration and decrease of contact angle of nanoparticles. Moreover, the reduction of supercooling degree caused by ultrasound and nanoparticles together do not exceed the sum of the supercooling degree reductions caused by ultrasound and nanoparticles separately; the reduction is even smaller than that caused by ultrasound individually under certain conditions of controlled nanoparticle concentration and contact angle and ultrasonic intensity. The dispersion stability of nanoparticles during solidification can be maintained only when the nanoparticles and ultrasound together show a superior effect on reducing the supercooling degree of water to the single operation of ultrasound. Otherwise, the aggregation of nanoparticles appears in water solidification, which results in failure. The relationships among the meaningful nanoparticle concentration, contact angle, and ultrasonic intensity, at which the requirements of low supercooling and high stability could be satisfied, were obtained. The control mechanisms for these phenomena were analyzed.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
HEAT AND MASS TRANSFER
·
2022
·Vol. 59
·期 5
·851-857
·
IF 2.325
Zhang Qian,Ma Fukun,Tan Wenjie,Liu Liqiang,Jing Min,Sun Tao
Inorganic hydrated salt calcium chloride hexahydrate (CaCl 2 ·6H 2 O) has a broad application prospect in the field of phase change energy storage due to its own characteristics. However, it has some problems such as large supercooling and serious phase separation, which limit its practical application. In this paper, boron nitride nanosheets (BNNSs) were applied in the CaCl 2 ·6H 2 O system. It was found that the heterogeneous nucleation of CaCl 2 ·6H 2 O can take place on the surface of BNNS. BNNS can solve the supercooling and heat transfer problems of CaCl 2 ·6H 2 O effectively. At the same time, the addition of an appropriate amount of BNNSs can improve the stability of phase change composites. Compared with pure CaCl 2 ·6H 2 O (supercooling was 22.06 °C and thermal conductivity was 0.382 W·m −1 ·K −1 ), the supercooling of CaCl 2 ·6H 2 O/1 wt% BNNS composite was only 3.89 °C and the thermal conductivity was 3.918 W·m −1 ·K −1 . CaCl 2 ·6H 2 O/0.5 wt% BNNS composite has good cycling stability. This study has scientific significance for the development and application of BNNSs in the field of phase change energy storage.
研究领域:
材料科学
·
能源存储
✓ 已验证
DOI
高影响因子
Journal of Energy Storage
·
2023
·
IF 9.4
Xue-Feng Shao,Sheng Yang,Hong-Yi Shi,Li-Wu Fan,Yan-Ping Yuan
Sugar alcohols have been proposed as a class of potential phase change materials (PCMs) for medium-temperature latent heat storage . The present work investigated the cycling stability of four pure and three mixture sugar alcohols by a specially-designed test setup, followed by a comprehensive evaluation based on their phase change behaviors (reported in our previous publication) and stability. It was found that the latent heats of fusion/crystallization degrade upon consecutive melting-crystallization cycles, and a higher degree of superheat Δ T sh leads to a faster degradation. An extremely low level of only 10.5 % degradation was obtained for erythritol after 200 cycles at a relatively low Δ T sh of 20 °C. The corresponding degrees of supercooling Δ T sc become higher due to the remarkable reduction of crystallization temperatures . It was shown that introducing protective nitrogen gas could suppress oxidation and improve cycling stability. The cycles of half degradation on latent heat of fusion was ~3.6 times with nitrogen protection. A comprehensive evaluation identified that the crystallization-related issues and poor stability are the primary challenges for sugar alcohols. Nevertheless, other than common PCMs, some particular application scenarios like controllable latent heat retrieval and seasonal heat storage can be hopefully developed by virtue of the deep supercooling nature of sugar alcohols.
研究领域:
材料科学
·
能源存储
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
·
2024
·
IF 6.4
Chongyang Wei,Yi Li,Jinliang Song,Jinxing Cheng,Zhongfeng Tang
The application of erythritol to medium-temperature latent heat energy storage systems is limited by its low thermal conductivity and large supercooling. Three types of graphite foams (GFs) with different thermal conductivities were used as the porous skeleton for encapsulating erythritol via vacuum impregnation, and the erythritol/GF composites were investigated using different methods to solve the aforementioned problems. The GF pores were effectively filled with erythritol via vacuum impregnation, and the filling rate of erythritol reached more than 90%. The thermal conductivity of the erythritol/GF composites was 73.80, 35.05, and 13.30 W/m·K. The thermal conductivity of the erythritol/GFs was improved by 26–158 times over that of pure erythritol. The subcooling degree of the erythritol/GF composites was reduced from 64.1 °C to 59.4 °C, facilitating the release of latent heat. The erythritol/GF composites had remarkably boosted thermal stability compared with that of pure erythritol. The developed erythritol/GF phase-change composite material exhibits excellent heat transfer and storage properties, and it has broad prospects in the field of phase-change heat storage at intermediate temperatures.
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
Journal of Energy Storage
·
2024
·
IF 8.9
Weisan Hua,Miaomiao Jiang,Xuelai Zhang,Qiang Sun,Wenzhuang Zhang
Calcium chloride hexahydrate (CCH) has a large latent heat of phase change, a high heat storage capacity and a relatively low cost, which makes it suitable for use in combination with the construction field. However, it has the problem of large supercooling, which limits its development and application. Studying the crystalline growth properties of calcium chloride hexahydrate is essential to comprehending or suppressing supercooling because the degree of supercooling is determined mainly by the room temperature(5–10 °C) melt structure of CCH and the structural factors that drive its supercooling behavior. Using a combination of macroscopic and microscopic research techniques, we explored the two features of the self-crystallization growth behavior of CCH at various initial concentrations and the crystallization growth behavior driven by the external addition of crystal nuclei were explored. The results showed that the water molecule content affects not only the product type but also the growth, development, and regrowth of crystals and crystal morphology. The observation of the triggered crystallization process under different nucleation types showed that the nucleation type affected the crystal growth, and SrCl 2 ·6H 2 O, which had a similar molecular structure, could replace the nucleation of CCH itself and accelerate the crystal growth process. At the same time, NaCl was more difficult to nucleate and inhibited crystal growth. To better understand subcooling and its inhibition, this paper examined the crystallization formation characteristics of CCH at various concentrations, compares and contrasts its crystallization characteristics under various nucleating agents as the triggering nuclei, and investigated the intrinsic mechanism of the nucleus type on its crystallization growth.
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
SOLAR ENERGY MATERIALS AND SOLAR CELLS
·
2017
·
IF 4.784
Yi Wang,Shuang Li,Ting Zhang,Deyi Zhang,Hui Ji
The main aim of this paper is to mitigate the supercooling and improve the heat release performance of erythritol (ET) as phase change material for thermal energy storage using the method of encapsulation and doping additives . The capsules containing ET, thickening and nucleating agent were prepared and various characterization techniques were employed to investigate the structure and thermo-physical properties of the composite, especially the supercooling inhibition and exothermicity improvement. Experimental results reveal that capsulation and adding thickening and nucleating agents have positive influence on the supercooling elimination, heat discharging ability improvement and thermal stability enhancement. The optimal capsules, with the maximal ET mass percentage of 59.2%, melt at 121.2 °C and freeze at 106.4 °C with the latent heat of 213.3 J/g and 206.9 J/g, respectively. Due to the improved crystallization kinetics , the degree of supercooling decreased by 83.6% as well as the heat release ratio increased by 52.2% compared to those of pristine ET. The as-prepared capsules have obvious core-shell structure, good compatibility between the shell and core materials. The thermal conductivity is 0.84 W/m K, increased by 29.2% than that of pristine ET. The results of accelerated thermal cycling test indicate that the supercooling, heat release ability and thermal reliability of encapsulated ET changed imperceptibly. In total, the technology of capsulation and adding thickening and nucleating agents can be used to suppress the supercooling and improve the thermal behavior of ET.
研究领域:
能源存储
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CRYSTAL GROWTH & DESIGN
·
2018
·
IF 3.972
Shijie Xu,Yifu Chen,Junbo Gong,Jingkang Wang
In this contribution, by employing the Poisson distribution combined with the regular solution theory in the classical nucleation theory (CNT) framework, we construct a new model to uncover the relationship between induction time (tind) and supercooling (ΔT) and saturation temperature (T0) at different specific probabilities. By choosing the urea aqueous solution as a benchmark system, we show that the value of ln(1/tind) follows a reasonable linear relationship with (T0/ΔT)2/(T0 – ΔT), except the probability value tends to be 0 or 1. Furthermore, we also shed new light on the role of chemical potential difference and nucleation temperature in determining the nucleation rate; namely, although the chemical potential difference is the driving force for the crystallization process, it does not always favor the nucleation process. We demonstrated that when the chemical potential difference increases as the nucleation temperature decreases (ΔT gradually increases), in this case, the kinetic factor overwhelms the thermodynamic factor thus leading to a faster nucleation rate by employing the CNT theory. However, when the chemical potential difference decreases as the nucleation temperature increases, we found that increasing the nucleation temperature favors the nucleation process both in kinetic and thermodynamic aspects.
研究领域:
物理化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2022
·Vol. 12
·期 27
·17217-17227
·
IF 4.036
Yuchen Yao,Yuntao Cui,Zhongshan Deng
Phase change materials (PCMs) have attracted more and more attention in the field of energy and thermal management due to the characteristic of exchanging heat with small temperature change. In order to obtain perfect PCMs, previous researchers usually prepared various phase change composites (PCCs), but there is still a gap toward the goal. Perhaps the development of PCMs with adjustable properties in a wide range to meet different needs is a feasible option. Given that the properties of organic PCMs and metal PCMs are highly complementary, using expanded graphite (EG) as a mediator, a stable PCC of octadecane and gallium that are difficult to directly mix, was successfully prepared. Octadecane and gallium are stored in the microstructures of EG, and the microstructures of EG play the role of storing nucleation embryos, and the suppression of supercooling can reach more than 86.82%. The test results showed that the properties of the PCC are indeed a balance between octadecane and gallium, and can be adjusted in a wide range. The PCC also has good structural and chemical stability, which can effectively avoid the corrosion risk caused by gallium leakage. The PCC samples containing equal amounts of gallium and paraffin were selected for thermal management performance tests. The results indicated that the PCC has application potential in related fields, and can provide a reference for the development of other PCCs.
研究领域:
材料科学
·
能源工程
·
热管理
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）