INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
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2023
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IF 5.2
Zhihao Sun,Kang Luo,Hongliang Yi,Jian Wu
The low thermal conductivity of organic phase change materials (PCMs) has seriously obstructed the performance of thermal latent-heat thermal storage (LHTS) system. For the first attempt, we experimentally studied the phase-change heat transfer characteristics of octadecane inside a horizontal cavity with the passive addition of nano graphene and the active application of an electric field. The effects of nano graphene weight ratio, direct current (DC) voltage magnitude and polarity on melting heat transfer and their corresponding mechanism are then examined. Results are reported for the real-time melting process, the liquid fraction, and the evolution of absorbed energy. The velocity fields obtained by particle image velocimetry (PIV), the temperature fields measured by fiber Bragg grating (FBG) sensors, and the current-voltage curves are reported to reveal the heat transfer enhancement mechanism. The absorbed thermal energy is increased by 33.6% when nano graphene is added alone. A single electric field promotes the energy absorption by 153.5% where electric field driven flow develops. The net charge is generated by the conduction mechanism. For composite PCMs’ melting, the absorbed energy is enhanced by 124.8% at most when the cavity's bottom wall is exposed to -10.0 kV. However, when +10.0 kV is applied to the bottom wall the electrophoretic deposition takes place, and the combined augmentation effect on absorbed thermal energy is 111.2%. The present results provide a reference for improving the LHTS system's performance through sole or synergistic heat transfer enhancement method.
研究领域:
材料科学
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热能工程
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纳米技术
✓ 已验证
产品关联
DOI
高影响因子
Journal of Physical Chemistry C
·
2014
·
IF 4.835
Li Ping Wang,Qi Feng Li,Chao Wang,Xiao Zheng Lan
Solid–liquid phase behaviors of the hexadecane–octadecane (n-C16H34–C18H38, C16–C18) system in the bulk, and confined in controlled porous glass (CPG) are investigated using differential scanning calorimetry and temperature-dependent powder X-ray diffraction. Bulk C16–C18 mixtures show the special rotator phase RI, and two intermediate phases with monoclinic (Mdcp) and orthorhombic (Op) structures. Inside CPG (8.1 and 300 nm), the RI and Op phases could be found in wider compositions of the solid mixtures than the bulk, however the Mdcp form was not observed. Unexpectedly, under the confinement of CPG (8.1 nm) not only the rotator RI appeared in the two pure components, C16 and C18, but a rotator phase RII occurred in the pure C18 and most of the mixtures upon heating. These new phase behaviors of the confined alkanes could be attributed to the size effect and the interface interactions. According to XRD analysis, in the small pores of CPG (8.1 nm) the alkane molecules effectively take the 2D arrangements. While in the large pores of CPG (300 nm), they take ordered packing to some extent both in the lamellar and lateral directions.
研究领域:
物理化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2024
·
IF 3
Chen Qingyi,Qu Meijie,Li Shuhui,Wang Hai,Tang Ping,Ma Yue,Zhang Rui,Wang Hongru,Bin Yuezhen
With the rapid growth of resource depletion, heat storage materials play a vital role in sustainable development. However, as a kind of heat storage material, phase change material (PCM) leaks easily when used, so anti-leak measures are crucial. In this study, microencapsulation phase change materials (MPCMs) were prepared by emulsifying first and then crosslinking, in which tetraethyl orthosilicate (TEOS) was used as the shell coating precursor, octadecane as the core and sodium dodecyl sulfonate (SDS) as the emulsifier. The grafted objects of Si–O bonds in TEOS were adjusted through different ratios of SDS/octadecane. The results showed that when the mass ratio of SDS/octadecane is 0.067, SDS is hydrolyzed to lauryl alcohol under acidic conditions and grafted with silica, and the phase transition temperature is − 20 °C. SDS gradually changed from graft to adhere with octadecane through sulfonic acid bond when the mass ratio of SDS/octadecane increased. Si–O bonds combine octadecane with sulfonic acid bonds through van der Waals forces and the indirect branches of Si–O bonds form an inorganic silica shell. When the mass ratio of SDS/octadecane is 0.15, the phase transition temperature was 23 °C and the phase transition enthalpy was 111.9 J g −1 . The obtained silica/octadecane MPCMs have small diameter, good thermal stability and the phase change enthalpy remains stable after 500 cycles, and the composite materials blended with polyvinyl alcohol also have good thermal properties. It is expected to be applied in the field of heat management textiles.
研究领域:
材料科学
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能源工程
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CLAY SCIENCE
·
2021
·
IF 5.467
Xing Li,Ya Wen,Yulian Zhang,Zhiqiang Ge
Insect pheromone is a class of natural non-toxic and harmless biological pesticide. To improve the utilization efficiency of the pheromone pesticides, controlled release in response to circadian rhythm of insects is a feasible approach because some insects act and release pheromones with a circadian rhythm. Thus, myrcene, as the insect pheromone model, was first loaded into the hollow nano-cavity of halloysite nanotubes (Hal), which were further enclosed with melted n-octadecane as a coating to form a composite (PMHal). The latter was simply blended into chitosan solution to cast a chitosan composite film (PMHal@CS) for preventing n-octadecane leakage during the phase change process . The effects of temperature change on the release rate of myrcene from the composite film were evaluated. Results showed the combination of Hal with n-octadecane could significantly slow the release rate of myrcene from the composite film when the ambient temperature was below 15 °C. If the ambient temperature was near to the melting point of n-octadecane, the release rate of myrcene would be enhanced. In alternating temperature cycles test of PMHal@CS film, the average release rate of myrcene was 0.65 μg/h at 30 °C and 0.022 μg/h at 15 °C, the persistent temperature sensitivity and good temperature rhythm were still remained after 7 cycles. These results suggested that the composite film had a good controlled release effect on myrcene and could adapt well to the circadian rhythm activity of some insects.
研究领域:
农业科学
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材料科学
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昆虫学
✓ 已验证
产品关联
DOI
高影响因子
MOLECULES
·
2024
·Vol. 29
·期 20
·4794
·
IF 4.2
Lin Lin,Ziqi Li,Jian Zhang,Tonghua Ma,Renzhong Wei,Qiang Zhang,Junyou Shi
Phase change energy storage microcapsules were synthesized in situ by using melamine-formaldehyde–urea co-condensation resin (MUF) as wall material, n-octadecane (C18) as core material and styryl-maleic anhydride copolymer (SMA) as emulsifier. Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry and thermogravimetric analysis were used to study the effects of emulsifier type, emulsifier dosage, core–wall ratio and pH on the morphology and thermal properties of microcapsules. The results show that the pH of core material and the ratio of core to wall have a great influence on the performance of microcapsules. SMA emulsifiers and MUF are suitable for the encapsulation of C18. When the pH is 4.5 and the core–wall ratio is 2/1, the latent heat and encapsulation efficiency of phase transition reaches 207.3 J g−1and 84.7%, respectively. The prepared phase-change microcapsules also have good shape stability and thermal stability.
研究领域:
材料科学
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能源存储
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Polymer Materials
·
2023
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IF 5
Jiale Xu,Sheng Chen,Junjie Wang,Jinghua Du,Xiaoyu Dong,Tao Zhang,Xiangjun Ren,Guozhi Liang,Fenfen Zhang,Xueliang Li,Haoyan Yin,Chao Liu,Ying Ke,Yan Zhao,Yunsheng Ding
Emulsion-templated, phase change material-encapsulated monolithic composites are advantageous for latent heat storage, but their infrared behavior and lack of stretchability hamper many more potential applications. Here, we report the fabrication of octadecane (OD)-encapsulated monolithic composites with flexibility and stretchability and their application for personal heat management for the first time. The composites were formed from interfacial cross-linking between isocyanate and poly(vinyl alcohol), which served as a monomer and an emulsion stabilizer. The composites showed flexibility over or slightly below the ambient temperature, robust compression (without leakage and fracture at 70% compressive strain), and high stretchability with tensile strain up to 30%. The heat storage and release temperatures were similar to that of OD, close to human body temperature, and the composites exhibited quite high heat density (up to 231.6 J g–1) and high reusability (without obvious decreases in heat density after 400 heating–cooling cycles). Moreover, the composites were verified effectively to decrease mean skin temperature and mean torso temperature of the human body, demonstrating to be a good candidate for personal heat management.
研究领域:
材料科学
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能源存储
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生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
Advances in Civil Engineering
·
2019
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IF 1.104
Jianping Zhu,Benkai Guo,Huanhuan Hou,Wenyan Zhang
Phase change materials (PCMs) have been widely used to improve the thermal energy storage capacity of building materials. In this study, the n-octadecane (OD)/expanded perlite (EP) composite PCM, which was prepared by incorporation of liquid n-octadecane into EP using the vacuum impregnation method, was used to fabricate the gypsum board. The microscopic, thermal, and mechanical properties were studied. The SEM results showed that OD could be absorbed into the pores of EP uniformly. The FI-IR results showed that OD and EP have good chemical stability. It was found that the gypsum board has best heat transfer delay when the volume fraction of OD/EP was 20% (v/v). The mechanical property of the gypsum board with OD/EP decreased. To deal with the problem, the effect of nano-Al2O3 on the gypsum board was also studied. The results showed that the mechanical properties of the gypsum board were effectively increased when the dosage of nano-Al2O3 was 0.5 wt.%, and the gypsum board had the best thermal insulation effect when the nano-Al2O3 content was 0.3 wt.%. Considering the cost and the comprehensive property, it was suggested that the optimal addition content of nano-Al2O3 was 0.3 wt.%.
研究领域:
建筑材料
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能源存储
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复合材料
✓ 已验证
产品关联
DOI
高影响因子
KEY ENGINEERING MATERIALS
·
2016
·
IF 0
Yan Yang Yang,Hao Wang,Guo Lin Song,Guo Yi Tang
Phase change method is one of the efficient approach in resolving energy problem for solar energy storage. However, phase change materials seriously affect the heat storage system with low heat releasing and absorbing rate for poor thermal conductivity performance, which result in an inefficient thermal energy storage technology and uncertain economic perspective. In this paper, we prepared dual-functional phase change nanocapsules based on n-octadecane core and polypyrrole shell. Polypyrrole was employed to enhance the electric conductivity and thermal conductivity. The nanocapsules was characterized using Fourier transformed infrared spectrophotometer (FTIR), field emission scanning electron microscope (FESEM), differential scanning calorimeter (DSC), thermal gravimetric analyzer (TGA) and infrared thermal imaging. The results shows a good thermal behavior and high latent heat of 81.99J/g. The dual-fuctional phase change nanocapsules can be expected with a prospect of future profits in energy storage technology.
研究领域:
材料科学
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能源技术
✓ 已验证
DOI
SOLAR ENERGY MATERIALS AND SOLAR CELLS
·
2021
·
IF 7.267
Ping Hu,Yang Feng,Qi Li,Chuan-Huang Lin,Yu-Hao Ning,Yi-Ting Li,Lin-Ping Yu,Zhong Cao,Ju-Lan Zeng
Microencapsulation of phase change materials (PCMs) with functional shell materials such as luminescent material could endow the obtained microencapsulated PCMs (MPCMs) with improved latent heat storage properties. The PCM core in turn could protect the luminescence shell from large temperature shifting and thus improve its performance. In this work, a series of MPCMs derived from n -octadecane (ODE) core and CaF 2 shell were synthesized via a self-assembly method. The effects of the preparation conditions, including the core/shell mass ratio, the dosage of the emulsifier (styrene-maleic anhydride copolymer , SMA) and the dosage of the chelator (Na 3 Cit), on the properties of the prepared ODE@CaF 2 MPCMs were investigated and the optimal preparation condition was obtained. The MPCM obtained according to the optimal procedure (MPCM1) exhibited an encapsulation ratio of 54.02% and a latent heat of 131 J/g with negligible leakage. It also possessed excellent thermal reliability and significantly improved thermal conductivity . The MPCM1 could not only be utilized as good latent heat storage material and thermal regulation material, but also provided one new idea to prevent the thermal quenching of luminescence materials. In addition, this work could shed some light on the high-value utilization of recovered fluorine resources.
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 LOSS PREVENTION IN THE PROCESS INDUSTRIES
·
2024
·
IF 3.6
Dongyan Yang,Lei Ni,Luping Gu,Qiang Chen,Juncheng Jiang,Jimi Su
Thermal runaway accounts for a high proportion of chemical safety accidents and poses a serious threat to the operational safety of personnel. Phase change materials (PCMs) have a high enthalpy of melting, if the latent heat energy of their phase change can be stored and used to absorb the heat released during thermal runaway, this phenomenon can provide a new approach for the control of reaction thermal runaway. In this work, microencapsulated phase change materials (microPCMs) were prepared by the suspension polymerization method using n -octadecane as the core material and polystyrene (PS) as the shell material. The prepared microPCMs had regular spherical morphologies with smooth surfaces, and the average particle size was 7.54 μm, the thermal conductivity was 0.05964 W/m∙K. The melting enthalpy of the microPCMs was 142.2 J/g, and the encapsulation percentage of the PCMs was 62.15%. The synthesis of the n -butylmagnesium bromide Grignard reagent occurred via a strong exothermic reaction, which was very likely to lead to overpressure venting once control was lost. The prepared microPCMs were applied as inhibitors in this reaction to investigate the temperature control effect under different operating conditions. The results showed that the amount of microPCMs added, and the timing of the addition affected the control effect. The addition of microPCMs could effectively reduce the reaction temperature and slow the rate of temperature increase. Even in the event of an emergency situation, such as a control failure, time could be gained for other emergency measures, effectively reducing the probability of thermal runaway accidents.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
THERMOCHIMICA ACTA
·
2021
·
IF 3.115
Lei Liu,Xiang Cheng,Xiwang Miao,Ying Zhang,Min Guo,Fangqin Cheng,Mei Zhang
In this work, a series of SiO 2 @n-octadecane capsules were prepared by one step emulsion polymerization, the influence of emulsifying speed, ammonia and TEOS contents, reaction temperature, concentration of emulsifier and the amount of PVP on the size, structure and performance was detailed investigated. It can be seen from SEM characterization that among these factors emulsification speed had the greatest influence on capsule size, while followed by the ammonia and TEOS content. According to TEM results, the ammonia and TEOS contents were the most important factors on the structure (shell thickness and surface smoothness) of the capsules, attributing to ammonia and TEOS were the catalyst and reactant of hydrolysis polymerization, respectively. Generally, the crystallinity of the samples became worse as the size decreased. DSC results showed that excessive ammonia or TEOS caused a significant drop in the enthalpy of the samples, furthermore, the enthalpy basically decreased with the attenuation of the inner radius of the sample. The target SiO 2 @n-octadecane capsule was sample C2 with high enthalpy (127.7 J/g), size of 1.62 μm, shell thickness of 68 nm, and smooth surface. More importantly, within the parameters studied, a series of SiO 2 @n-octadecane capsules were successfully synthesized with different enthalpy values (min 85.9 J/g, max 144.3 J/g), sizes ranging from 0.63–2.75 μm, shell thickness 32–79 nm and different smooth surfaces. Therefore, the controllable synthesis of SiO 2 @n-octadecane capsules within the above range can be achieved by simulating different parameters and their development.
研究领域:
材料科学
·
化学工程
✓ 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）