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Effect of graphene and its derivatives on thermo-mechanical properties of phase change materials and

《能源前沿（英文）》 2022年第16卷第2期页码 150-186 doi: 10.1007/s11708-021-0795-3

摘要： Phase change materials (PCMs) play a leading role in overcoming the growing need of advanced thermal management for the storage and release of thermal energy which is to be used for different solar applications. However, the effectiveness of PCMs is greatly affected by their poor thermal conductivity. Therefore, in the present review the progress made in deploying the graphene (Gr) in PCMs in the last decade for providing the solution to the aforementioned inadequacy is presented and discussed in detail. Gr and its derivatives ((Gr oxide (GO), Gr aerogel (GA) and Gr nanoplatelets (GNPs)) based PCMs can improve the thermal conductivity and shape stability, which may be attributed to the extra ordinary thermo-physical properties of Gr. Moreover, it is expected from this review that the advantages and disadvantages of using Gr nanoparticles provide a deep insight and help the researchers in finding out the exact basic properties and finally the applications of Gr can be enhanced.

关键词： phase change materials (PCMs) graphene thermal conductivity characterization

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Analysis of the radiation heat transfer process of phase change for a liquid droplet radiator in space

Jinying YIN, Linhua LIU

《能源前沿（英文）》 2011年第5卷第2期页码 166-173 doi: 10.1007/s11708-010-0105-y

摘要： The optimization of a space power system is greatly affected by the radiation heat transfer in a liquid droplet radiator (LDR). Radiation heat transfer in a two-dimensional bed of phase-change particle is modeled by solving the radiative transfer equation using the discrete ordinates method and the energy equation using the implicit finite difference method. The Mie theory is used to calculate the radiative properties of the droplet bed, whereas the effective medium theory is used to obtain the optical constants of partial solidification droplets. Multiple factors affect heat flux in the LDR, such as size distribution, flow velocity, phase change of droplets, layer thickness, droplet concentration in the layer, and material type of the work fluid; each of these must be analyzed. Calculations show that once size distribution is neglected, the relative error increases significantly. Size distribution has a remarkably strong effect on heat flux when the flow velocity of the working fluid is above 100 m/s. An increase in flow velocity leads to an increase in the total heat flux for the layer with a fixed volume fraction of droplets. The solidification zone occupies nearly half of the layer, and droplets of different sizes exhibit temperature differences to some extent due to local thermal non-equilibrium among them. Droplet concentration in the layer and the material type of the working fluid have strong effects on heat flux, whereas the thickness of the layer has a mild influence on heat flux.

关键词： radiation heat transfer particle polydispersion liquid droplet radiator phase change

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Heat transfer of phase change materials (PCMs) in porous materials

C Y ZHAO, D ZHOU, Z G WU

《能源前沿（英文）》 2011年第5卷第2期页码 174-180 doi: 10.1007/s11708-011-0140-3

摘要： In this paper, the feasibility of using metal foams to enhance the heat transfer capability of phase change materials (PCMs) in low- and high-temperature thermal energy storage systems was assessed. Heat transfer in solid/liquid phase change of porous materials (metal foams and expanded graphite) at low and high temperatures was investigated. Organic commercial paraffin wax and inorganic calcium chloride hydrate were employed as the low-temperature materials, whereas sodium nitrate was used as the high-temperature material in the experiment. Heat transfer characteristics of these PCMs embedded with open-cell metal foams were studied. Composites of paraffin and expanded graphite with a graphite mass ratio of 3%, 6%, and 9% were developed. The heat transfer performances of these composites were tested and compared with metal foams. The results indicate that metal foams have better heat transfer performance due to their continuous inter-connected structures than expanded graphite. However, porous materials can suppress the effects of natural convection in liquid zone, particularly for PCMs with low viscosities, thereby leading to different heat transfer performances at different regimes (solid, solid/liquid, and liquid regions). This implies that porous materials do not always enhance heat transfer in every regime.

关键词： heat transfer thermal energy storage phase change materials natural convection porous media

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study and assessment of thermal energy storage mortar with paraffin/recycled brick powder composite phasechange materials

Luchen HAO; Jianzhuang XIAO; Wanzhi CAO; Jingting SUN

《结构与土木工程前沿（英文）》 2022年第16卷第10期页码 1301-1314 doi: 10.1007/s11709-022-0883-4

摘要： Thermal energy storage recycled powder mortar (TESRM) was developed in this study by incorporating paraffin/recycled brick powder (paraffin/BP) composite phase change materials (PCM). Fourier transform infrared and thermogravimetric analysis results showed that paraffin/BP composite PCM had good chemical and thermal stability. The onset melting temperature and latent heat of the composite PCM were 46.49 °C and 30.1 J·g⁻¹. The fresh mortar properties and hardened properties were also investigated in this study. Paraffin/BP composite PCM with replacement ratio of 0%, 10%, 20%, and 30% by weight of cement were studied. The results showed that the static and dynamic yield stresses of TESRM were 699.4% and 172.9% higher than those of normal mortar, respectively. The addition of paraffin/BP composite PCM had a positive impact on the mechanical properties of mortar at later ages, and could also reduce the dry shrinkage of mortar. The dry shrinkage of TESRM had a maximum reduction about 26.15% at 120 d. The thermal properties of TESRM were better than those of normal mortar. The thermal conductivity of TESRM was 36.3% less than that of normal mortar and the heating test results showed that TESRM had good thermal energy storage performance.

关键词： recycled powder mortar recycled brick powder thermal energy storage paraffin phase change material

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Thermal performance of phase change material energy storage floor for active solar water-heating system

Ruolang ZENG, Xin WANG, Wei XIAO, Yinping ZHANG, Qunli ZHANG, Hongfa DI,

《能源前沿（英文）》 2010年第4卷第2期页码 185-191 doi: 10.1007/s11708-009-0079-9

摘要： The conventional active solar water-heating floor system contains a big water tank to store energy in the day time for heating at night, which takes much building space and is very heavy. In order to reduce the water tank volume or even cancel the tank, a novel structure of an integrated water pipe floor heating system using shape-stabilized phase change materials (SSPCM) for thermal energy storage was developed and experimentally studied in this paper. The thermal performances of the floors with and without the SSPCM were compared under the intermittent heating condition. The results show that the Energy Storage Ratio (ESR) of the SSPCM floor is much higher than that of the non-SSPCM floor; the SSPCM floor heating system can provide stable heat flux and prevent a large attenuation of the floor surface temperature. Also, the SSPCM floor heating system dampens the indoor temperature swing by about 50% and increases the minimum indoor air temperature by 2°C–3°C under experimental conditions. The SSPCM floor heating system has a potential of making use of the daytime solar energy for heating at night efficiently.

关键词： phase change material energy storage ratio active solar water-heating

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Lamellar thickness transition of melt-crystallized polybuten-1 tetragonal phase: configurational change

Motoi YAMASHITA

《化学科学与工程前沿（英文）》 2009年第3卷第1期页码 26-32 doi: 10.1007/s11705-009-0002-2

摘要： Lamellar crystal thickness of isotactic polybutene-1 ( -PB1) have been investigated for crystallization in the melt over a wide range of crystallization temperature from 40°C to 90°C by small angle X-ray scattering experiments and density measurements. The crystal thickness demonstrates two linear dependences on inverse supercooling and a transition from one dependence to the other has been observed around = 65°C. Each of the two dependences obeys the nucleation theory in the high and low supercooling ranges, respectively. Chain folding free energy determined from the low supercooling range is larger than that determined from the high supercooling range. Possible mechanisms for the transition are discussed taking account of entropy of chain folding directions.

关键词： isotactic polybutene-1 tetragonal phase crystal thickness melt growth chain folding small angle X-ray scattering nucleation theory end surface free energy

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Phase change effect of low melting point metal for an automatic cooling of USB flash memory

Haoshan GE, Jing LIU

《能源前沿（英文）》 2012年第6卷第3期页码 207-209 doi: 10.1007/s11708-012-0204-z

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Ultrafast solid-liquid-vapor phase change of a thin gold film irradiated by femtosecond laser pulses

Jing HUANG, Yuwen ZHANG, J. K. CHEN, Mo YANG

《能源前沿（英文）》 2012年第6卷第1期页码 1-11 doi: 10.1007/s11708-012-0179-9

摘要： Effects of different parameters on the melting, vaporization and resolidification processes of thin gold film irradiated by femtosecond pulses and pulse train were systematically studied. The classical two-temperature model was adopted to depict the non-equilibrium heat transfer in electrons and lattice. The melting and resolidification processes, which was characterized by the solid-liquid interfacial velocity, as well as elevated melting temperature and depressed solidification temperature, was obtained by considering the interfacial energy balance and nucleation dynamics. Vaporization process which leads to ablation was described by tracking the location of liquid-vapor interface with an iterative procedure based on energy balance and gas kinetics law. The parameters in discussion included film thickness, laser fluence, pulse duration, pulse number, repetition rate, pulse train number, etc. Their effects on the maximum lattice temperature, melting depth and ablation depth were discussed based on the simulation results.

关键词： melting evaporation nucleation dynamics nanoscale heat transfer

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相变蓄热材料在高超声速飞行器热控系统中的应用

王佩广,刘永绩,王浚

《中国工程科学》 2008年第10卷第7期页码 188-192

摘要：

就高超声速飞行器防热与热控问题，从“相变蓄热材料充当辅助冷源”思路出发，结合不同飞行器的飞行特点，提出了５种热控系统方案，即空气循环热控方案、蒸发循环热控方案、液体冷却回路方案、开式蒸发冷却热控方案、直接式相变蓄热冷却方案；指出了选择合适相变蓄热材料及相变蓄热封装设计是其中的关键技术，并结合航空航天领域相关技术进行了探讨与分析

关键词：相变蓄热材料热控高超声速飞行器

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Importance of emulsions in crystallization—applications for fat crystallization

Sandra PETERSEN, K. CHALEEPA, Joachim ULRICH

《化学科学与工程前沿（英文）》 2013年第7卷第1期页码 43-48 doi: 10.1007/s11705-013-1309-6

摘要： Emulsions and crystallization are two independent research topics which normally do not overlap although a combination of the two could be applicable to many areas. Here, the importance of emulsions in the field of fat crystallization is described. Three applications with industrial relevance were chosen for investigation: fat fractionation, the solidification of phase change materials and solid lipid nanoparticles. For fat fractionation and phase change materials, emulsification can be applied as a tool to improve the fat crystallization process, and thus the product quality of the crystallized fat. Furthermore, the use of emulsification creates new application fields such as solid lipid nanoparticles in the area of fat crystallization.

关键词： emulsion fat crystallization phase change material emulsion fractionation emulsion solidification

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Encapsulation of polyethylene glycol in cellulose-based porous capsules for latent heat storage and light-to-thermal conversion

《化学科学与工程前沿（英文）》 2023年第17卷第8期页码 1038-1050 doi: 10.1007/s11705-022-2279-3

摘要： Phase change materials are potential candidates for the application of latent heat storage. Herein, we fabricated porous capsules as shape-stable materials from cellulose-based polyelectrolyte complex, which were first prepared using cellulose 6-(N-pyridinium)hexanoyl ester as the cationic polyelectrolyte and carboxymethyl cellulose as the anionic polyelectrolyte to encapsulate polyethylene glycol by the vacuum impregnation method. Furthermore, the multi-walled carbon nanotube or graphene oxide, which were separately composited into the polyelectrolytes complex capsules to enhance thermal conductivity and light-to-thermal conversion efficiency. These capsules owned a typical core–shell structure, with an extremely high polyethylene glycol loading up to 34.33 g∙g^‒1. After loading of polyethylene glycol, the resulted cellulose-based composite phase change materials exhibited high thermal energy storage ability with the latent heat up to 142.2 J∙g^‒1, which was 98.5% of pure polyethylene glycol. Further results showed that the composite phase change materials demonstrated good form-stable property and thermal stability. Moreover, studies involving light-to-thermal conversion determined that composite phase change materials exhibited outstanding light-to-thermal conversion performance. Considering their exceptional comprehensive features, innovative composite phase change materials generated from cellulose presented a highly interesting choice for thermal management and renewable thermal energy storage.

关键词： cellulose polyelectrolytes phase change materials thermal energy storage light-to-thermal conversion

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Fabrication of form stable NaCl-Al2O3 composite for thermal energy storage by cold sintering process

Bilyaminu Suleiman, Qinghua Yu, Yulong Ding, Yongliang Li

《化学科学与工程前沿（英文）》 2019年第13卷第4期页码 727-735 doi: 10.1007/s11705-019-1823-2

摘要： A form stable NaCl-Al O (50-50 wt-%) composite material for high temperature thermal energy storage was fabricated by cold sintering process, a process recently applied to the densification of ceramics at low temperature ˂ 300°C under uniaxial pressure in the presence of small amount of transient liquid. The fabricated composite achieved as high as 98.65% of the theoretical density. The NaCl-Al O composite also retained the chloride salt without leakage after 30 heating-cooling cycles between 750°C–850°C together with a holding period of 24 h at 850°C. X-ray diffraction measurements indicated congruent solubility of the alumina in chloride salt, excellent compatibility of NaCl with Al O , and chemical stability at high temperature. Structural analysis by scanning electron microscope also showed limited grain growth, high density, uniform NaCl distribution and clear faceted composite structure without inter-diffusion. The latent heat storage density of 252.5 J/g was obtained from simultaneous thermal analysis. Fracture strength test showed high sintered strength around 5 GPa after 50 min. The composite was found to have fair mass losses due to volatilization. Overall, cold sintering process has the potential to be an efficient, safe and cost-effective strategy for the fabrication of high temperature thermal energy storage materials.

关键词： cold sintering process composite fabrication thermal energy storage phase change materials

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Climate change and China’s mega urban regions

Chaolin GU, Sunsheng HAN

《结构与土木工程前沿（英文）》 2010年第4卷第4期页码 418-430 doi: 10.1007/s11709-010-0075-5

摘要： China’s mega urban regions are focal points of economic development and environmental concerns. This paper positions four mega urban regions (i.e., the Yangtze River Delta, the Pearl River Delta, the Bohai Bay Area, and the South-eastern Fujian Province) along China’s coast into the national economy and elaborates their development challenges and planning innovations. Mega urban regions in China are spatial consequences of rapid economic transition. They deserve close scrutiny and demands for innovative planning responses in order to maintain their key role in driving economic growth but limiting their greenhouse gas emission.

关键词： climate change mega urban region urban planning

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基于电流滑模控制策略的五相感应电机指数响应电子变极技术 Article

Jia-qiang YANG, Rong-sen YIN, Xiao-jun ZHANG, Jin HUANG

《信息与电子工程前沿（英文）》 2017年第18卷第8期页码 1151-1166 doi: 10.1631/FITEE.1601728

摘要：现有电子变极技术可以拓宽多相感应电机系统的恒功率调速范围，但是会带来转矩脉动和转速波动。为减小电机在变极过程中的转矩脉动和转速波动，本文研究了基于电流滑模控制策略的五相感应电机指数响应电子变极技术。本技术采用双平面（d1-q1和d2-q2）矢量控制策略，使五相感应电机可以在不同的极对数模式下运行。电流滑模控制器取代了传统的PI控制器，以调节电流矢量，并且电流指数响应可以实现d1-q1和d2-q2平面之间平滑的切换。同基于PI控制的阶跃响应电子变极技术相比，本文提出的方法极大地减小了感应电机在电子变极过程中的转矩脉动和速度波动。实验结果证明了本文所提出方法的有效性。

关键词：五相感应电机；电子变极；滑模控制；指数响应；转矩脉动减小

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Tackling climate change and promoting the energy revolution

Xiangwan DU

《能源前沿（英文）》 2018年第12卷第3期页码 338-343 doi: 10.1007/s11708-018-0535-5

摘要：

Following the Paris Agreement, green and low-carbon development has entered into a new stage. China’s international responsibility to combat climate change is consistent with the inherent sustainable development needs of the country. In this paper, the reasonability of China’s Intended Nationally Determined Contributions (INDC) is examined and the fact that low-carbon development can lead to modernization is demonstrated based on data analysis of energy economics from developed countries. Considering the fact that such an energy revolution forms the basis for China’s low-carbon transition, a roadmap of the China’s energy utilization is presented. Based on research results from the Chinese Academy of Engineering, the three historical stages of China’s energy structure reform are analyzed. Promoting a low-carbon transition through an energy revolution is a long-term and arduous process that requires a genuine transformation of development outlook and patterns. By empirically analyzing situations at home and abroad, a conclusion is made that economic development and a low-carbon transition can be achieved simultaneously; specifically, low-carbon development fosters new points of economic growth and gives rise to different development paths.

关键词： climate change Paris Agreement low-carbon transition energy revolution