APPLIED THERMAL ENGINEERING
·
2018
·
IF 3.771
Siyu Zhou,Yan Zhou,Ziye Ling,Zhengguo Zhang,Xiaoming Fang
MgCl 2 ·6H 2 O is a promising inorganic phase change material (PCM) with abundant resources from salt lakes, while its wide applications are greatly hampered by the drawbacks of phase separation, supercooling and corrosivity, inherent in hydrated salts. Herein a novel expanded graphite (EG) based composite PCM containing MgCl 2 ·6H 2 O was explored, which involved modifying EG for increasing its hydrophilicity, compressing the modified EG (MEG) into round blocks, and immersing the blocks into melted MgCl 2 ·6H 2 O. The optimal mass ratio of TX-100 to EG and the favorable packing density of the MEG block are determined to be around 0.06 and 350 kg/m 3 , at which the adsorptive capacity of the modified EG block reaches 80% for MgCl 2 ·6H 2 O, larger than 73% of the unmodified one. The as-prepared MgCl 2 ·6H 2 O/MEG composite block, which consists of 80.1% of MgCl 2 ·6H 2 O, 1.1% of TX-100, and 18.8% of EG, maintains a similar melting point to that of MgCl 2 ·6H 2 O, and its latent heat is as high as 116.7 J/g. Furthermore, the supercooling degree of the composite block is found to be around 1.3 °C, much less than 11.2 °C of MgCl 2 ·6H 2 O. The thermal conductivity of the composite block is about 7.7 times as large as that of MgCl 2 ·6H 2 O. And the composite exhibits a decrease only by 2.7% in phase change enthalpy after 500 thermal cycles, much lower than 41.7% for MgCl 2 ·6H 2 O. These good thermal characteristics make the MgCl 2 ·6H 2 O/MEG composite PCM show great potentials in practical applications.
研究领域:
材料科学
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能源工程
✓ 已验证
DOI
高影响因子
AUSTRALIAN JOURNAL OF CHEMISTRY
·
2018
·Vol. 71
·期 6
·416-421
·
IF 1.059
Ouyang Dong,Zhihong Zhang,Zhenhai Fu,Xiang Li
A new phase-change material (PCM) CaCl2·6H2O + MgCl2·6H2O + NH4Cl was investigated in this paper. MgCl2·6H2O and NH4Cl were mixed with CaCl2·6H2O to obtain CaCl2·6H2O as a eutectic hydrate salt. The results show that the eutectic composition of the PCM is as follows: 90 wt- % CaCl2·6H2O, 6.25 wt- % MgCl2·6H2O and 3.75 wt- % NH4Cl; the undercooling degree is less than 1.5°C when the nucleating agent is 2 wt- % SrCl2·6H2O or 1.5 wt- % Ba(OH)2·8H2O. The phase-change temperature and latent heat are respectively 25.3°C and 144.3 J g−1 when the composition is 90 wt- % CaCl2·6H2O, 6.25 wt- % MgCl2·6H2O, 3.75 wt- %, NH4Cl, with 2 wt- % SrCl2·6H2O as nucleating agent, and 2 wt- % carboxymethyl cellulose as thickener. In addition, when the composition is changed to 90 wt- % CaCl2·6H2O, 6.25 wt- % MgCl2·6H2O, 3.75 wt- % NH4Cl, 1.5 wt- % Ba(OH)2·8H2O and 2 wt- % carboxymethyl cellulose, the phase change temperature and latent heat are 25.2°C and 139.3 J g−1, respectively.
研究领域:
材料科学
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热能存储
·
化学工程
✓ 已验证
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2020
·
IF 7.632
Xiaojuan Zhang,Edouard Asselin,Zhibao Li
The precipitation of CaCO3 and its kinetics for the CaCl2–CO2–Mg(OH)2–H2O system were systematically studied to develop a novel process for eliminating solid and liquid waste from the Solvay soda process. The effects of operating conditions including temperature, CaCl2 concentration, flow rate of CO2, and stirring speed on the reaction kinetics were experimentally determined. The results revealed that low temperature, high CO2 flow rate, and fast stirring speed can accelerate the reaction rate, and the mass transfer of CO2 is the controlling step. An MSMPR crystallizer was used to obtain the experimental crystal size distribution (CSD). A simplified population balance equation (PBE) was used to correlate the parameters on the basis of supersaturation. The soda solid and liquid wastes discharged from the Solvay industry were used as raw material to test the new process and validate the methodology. The precipitated CaCO3 consists of calcite or aragonite with high purity and uniform CSD. A double-effect evaporative-cooling crystallization process to recover MgCl2·6H2O and NaCl was simulated with help of Aspen plus and the electrolyte-NRTL (ELENRTL) model, suggesting economic benefits.
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
SOLAR ENERGY MATERIALS AND SOLAR CELLS
·
2014
·
IF 5.03
Gang Li,Binbin Zhang,Xiang Li,Yuan Zhou,Qingguo Sun,Qiang Yun
The preparation, characterization and modification of eutectic hydrate salt (CaCl 2 ·6H 2 O–MgCl 2 ·6H 2 O) as a new phase change material (PCM) were investigated in this paper. CaCl 2 ·6H 2 O was prepared using industrial grade calcium chloride (CaCl 2 ), and then 10, 15, 20 and 25 wt% MgCl 2 ·6H 2 O was added into CaCl 2 ·6H 2 O respectively in order to obtain CaCl 2 ·6H 2 O–MgCl 2 ·6H 2 O eutectic hydrate salt PCM. The modification of CaCl 2 ·6H 2 O-25 wt% MgCl 2 ·6H 2 O material was designed by a uniform experimental method to select the efficient nucleating and thickening agents. The results show that SrCl 2 ·6H 2 O and SrCO 3 can be effective nucleating agents , and hydroxyethyl cellulose (HEC) is an excellent thickener. For CaCl 2 ·6H 2 O-25 wt% MgCl 2 ·6H 2 O material with 3 wt% SrCl 2 ·6H 2 O, 1 wt% SrCO 3 and 0.5 wt% HEC, the supercooling is reduced to 2 °C, and its phase change temperature and latent heat are 21.4 °C and 102.3 J/g, respectively.
研究领域:
材料科学
·
储能技术
·
热能工程
✓ 已验证
DOI
高影响因子
SOLAR ENERGY MATERIALS AND SOLAR CELLS
·
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
JOURNAL OF APPLIED ELECTROCHEMISTRY
·
2018
·Vol. 48
·期 10
·1131-1138
·
IF 2.262
Ling Ziye,Li Suimin,Zhang Zhengguo,Fang Xiaoming,Gao Xuenong,Xu Tao
Abstract Household water heating systems incorporating phase change materials (PCMs) can store solar thermal energy and reduce energy consumption. MgCl 2 ·6H 2 O–Mg(NO 3 ) 2 ·6H 2 O eutectics have a melting point near 60 °C with a large energy storage density suitable for use in the thermal energy storage unit of a water heating system. However, the low thermal conductivity of the eutectic limits its heat extraction rate. In this study, we combine the eutectic and expanded graphite (EG) to prepare a high thermal conductivity composite PCM and study its cycling performance over 200 thermal cycles. The thermal conductivity of the composite PCM increased from 0.5 to 3.7 W m −1 K −1 , ensuring faster heating and cooling. The images obtained from scanning electron microscopy and leakage testing showed that the maximum loading mass fraction of the eutectic in the EG reached 85 wt %. Infrared spectra and X-ray diffractometry patterns confirm that composites with compositions between those of EG and the eutectic were composed of the physical mixture. Thermogravimetric analysis indicated that the composite PCM lost less mass at 300 °C compared to the pure eutectic, and differential scanning calorimetry demonstrated that the composite PCM had a melting point of 52.3 °C and a small subcooling degree of 2.7 °C, compared to 56.6 and 18.4 °C for the pure eutectic, respectively. All these measurements demonstrated that the composite PCMs changed less after 200 thermal cycles than the pure eutectic, which had an observable stratification caused by phase separation. The composite PCM developed was thermally conductive, shape-stabilized, and more thermally stable during cycling than the pure eutectic. Graphical Abstract
研究领域:
能源材料
·
热能工程
✓ 已验证
产品关联
DOI
高影响因子
APPLIED THERMAL ENGINEERING
·
2020
·
IF 4.725
Tao Wang,Xishan Zhou,Zhao Liu,Jiawei Wang,Yongsheng Zhang,Wei-Ping Pan
As an inorganic phase change material (PCM), CaCl 2 ·6H 2 O is an effective energy storage material because its energy can be transformed around 30 °C through the melting and crystallization. The different compositions of PCM were prepared in order to decrease the phase transition temperature to 20–25 °C and to improve its capability of heat storage and release. MgCl 2 ·6H 2 O was added as a nucleating agent and the composite PCMs (CPCMs) of CaCl 2 ·6H 2 O/MgCl 2 ·6H 2 O binary salt system was prepared. At the same time, SrCl 2 ·6H 2 O was added to reduce the supercooling degree of inorganic PCM. As a thickener, hydroxyethyl cellulose (HEC) was also included to improve the recycling ability. With the application of thermogravimetric analysis and differential scanning calorimeter, the phase transition temperature, thermal properties of CPCMs, supercooling degree and thermal cycle performance were studied by changing the content of each component in the CPCMs. The results demonstrated that the phase transition temperature of PCM with 35% MgCl 2 ·6H 2 O, 5% SrCl 2 ·6H 2 O, 0.5% HEC balanced by CaCl 2 ·6H 2 O was reached to 23 °C. The phase change latent heat of PCM was kept at 130 J/g. The degree of supercooling was kept within 0.7 °C and the recyclability was greatly improved after 100 cycles.
研究领域:
材料科学
·
热能存储
·
相变材料
✓ 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）