INTERNATIONAL JOURNAL OF ENERGY RESEARCH
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2020
·Vol. 44
·期 11
·8555-8566
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IF 3.741
Li Yang,Yanping Yuan,Nan Zhang,Yanfang Dong,Yafen Sun,Wenhui Ji
Summary To make better use of solar energy, lauric acid/expanded graphite (LA/EG) composite phase change materials (PCMs) were synthesized to collect and store solar energy as latent heat thermal energy. The results of thermal characteristics show that when the mass fraction of EG is 5%, 10%, and 15%, the latent heat of LA/EG is 164.5, 156.9, and 148.0 J/g, and the thermal conductivity is 2.73, 7.98, and 10.54 W/(m·K). Leakage test shows that LA/EG PCMs with EG mass fraction of 10% and 15% are form stable after phase change. One thousand thermal cycles prove good thermal reliability of LA/EG. TG analysis indicates LA/EG PCMs have good thermal stability within operating temperature range. The Ultraviolet-visible spectra reveal that the absorbance of LA/EG composite PCMs would increase as the mass fraction of EG increases. Photothermal conversion experiment results indicate that the photothermal conversion efficiency of LA/EG composite PCMs increases as the mass fraction of EG increases, and the efficiency can reach 95% when the mass fraction of EG is 15%. Moreover, it was also found that the process of photothermal conversion can be accelerated with stronger illumination intensity or smaller heat transfer size. All the results show that the prepared LA/EG PCMs can convert solar energy into thermal energy and store it in the form of latent heat at the same time, which indicates it has promising prospect in the application of solar energy conversion and storage.
研究领域:
材料科学
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能源化学
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热能工程
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功能材料
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可再生能源
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Mengdi Yuan,Chao Xu,Tieying Wang,Tianying Zhang,Xinyu Pan,Feng Ye
The serious supercooling of erythritol (ET) limits its application in the field of mid-temperature thermal energy storage (TES), especially in the recently developed form-stable phase change materials (PCMs). The primary purpose of this paper is to find out the factors to mitigate the supercooling of ET/expanded graphite (EG) form-stable composite PCM and obtain the correlation among the morphology, kinetic parameters, and a supercooling degree in the non-isothermal crystallization process. Firstly, five types of supercooling relaxation agents (nano-Al 2 O 3 , nano-SiO 2 , CMC, urea, and citric acid) were added to prepare the ET/EG form-stable CPCMs. Among them, the ET/EG/nano-Al 2 O 3 exhibited excellent form-stable ability, a high heat release ratio of 78.9%, and the lowest supercooling degree (Δ T ) of 45.7 °C. Based on the chosen ET/EG/nano-Al 2 O 3 CPCM, the tablet pressures from 1 to 13 MPa were applied, obtaining lowest Δ T decreased by 59.0% in 1 MPa. Moreover, the non-isothermal crystallization processes were discussed on the ET/EG/nano-Al 2 O 3 with the Avrami equation modified by Jeziorny. ET tended to grow spherulites under the high cooling rate of 18 °C/min with triggering as the Johnson-Mehl-Avrami exponent n increased to 4.22. Meanwhile, the supercooling degree increased from 48.8 to 56 °C with the cooling rate growing from 2 to 18 °C/min. And the activity energy Δ E of the ET/EG/nano-Al 2 O 3 CPCM (7092.35 kJ/mol) was smaller than that of the ET/EG CPCM (8211.19 kJ/mol) because of the interaction between the heterogeneous nucleation effect and blocker effect of nano-Al 2 O 3 .
研究领域:
材料科学
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热能存储
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物理化学
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复合材料
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能源材料
✓ 已验证
DOI
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 59
·34658-34670
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IF 3.049
Xiangyu Wang,Yu Xie,Jun Ma,Ping Ning
The two-stage removal process of tetracycline (TC) in aqueous solutions using a novel photocatalyst based on nano-zero-valent iron (NZVI), g-C3N4 and expanded graphite by carbon layer (EGC) is reported for the first time. The composite (NZVI/g-C3N4@EGC) exhibits remarkable adsorption, reduction ability and visible light activity over the reaction course. Compared with pristine g-C3N4 (25.9%) and pure NZVI (45.9%), NZVI/g-C3N4@EGC achieves high degradation efficiency of TC (98.5%) due to the formation of a heterogeneous photo-Fenton system. This study shows that synergistic effects are achieved in the reaction system, including maintaining the reduction ability of NZVI and enhancing the photocatalytic activity of g-C3N4 by facilitating the separation of photogenerated electrons (e−) and holes (h+). TC removal involved a two-stage process of adsorption–reduction and photo-degradation. The quencher experiments determined that holes (h+) and superoxide radicals (˙O2−) are the major reactive species in the degradation of TC. The degradation pathways of TC were proposed based on the analysis of the intermediates. In addition, NZVI/g-C3N4@EGC revealed a high stability in a five-cycle test and good magnetic properties for facile separation from aqueous solutions. From an application viewpoint, NZVI/g-C3N4@EGC has favorable prospects in the direction of the photocatalytic degradation of antibiotic wastewater.
研究领域:
环境化学
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材料科学
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光催化
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水污染治理
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纳米复合材料
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抗生素降解
✓ 已验证
DOI
高影响因子
MATERIALS LETTERS
·
2014
·
IF 2.269
Yaguang Yuan,Yanping Yuan,Nan Zhang,Yanxia Du,Xiaoling Cao
Capric–myristic–palmitic acid ternary eutectic mixture (CA–MA–PA) was prepared as phase change material (PCM). A novel composite PCM of CA–MA–PA/expanded graphite (EG) with an optimum mass ratio (CA–MA–PA:EG=13:1) was prepared by uniformly absorbing CA–MA–PA into the porous network structure of the EG. The melting and freezing temperatures of CA–MA–PA/EG composite PCM were measured by differential scanning calorimeter as 18.61 °C and 16.58 °C, respectively, while the melting and freezing latent heats were 128.2 J/g and 124.5 J/g, respectively. The thermal conductivity of the CA–MA–PA/EG composite PCM was measured as 3.67 W/m K and thus the thermal storage and release rates were significantly increased. The thermal cycling test results showed that CA–MA–PA/EG composite PCM has a good thermal reliability. All the above results show that the CA–MA–PA/EG composite PCM is a potential solution for latent heat storage system.
研究领域:
材料科学
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能源化学
·
热物理
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功能材料
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储能技术
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）