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Dynamic characteristics of molten droplets and hot particles falling in liquid pool

Liangxing LI, Weimin MA, Huixiong LI, Tingkuan CHEN,

《能源前沿（英文）》 2010年 第4卷 第2期   页码 246-251 doi: 10.1007/s11708-009-0077-y

摘要： The dynamic characteristics of molten droplets and hot particles at the very beginning of their fall into coolant pools are presented. The falling course of a single droplet or a single hot particle was recorded by a high-speed camera and a curve of velocity . time was obtained. Emphasis was placed on the effects of the droplet’s size and temperature, the coolant’s temperature and properties, and the droplet’s physical properties on the moving behavior. The results for the all cases showed that the velocity of a falling droplet/particle decreased rapidly but rebounded shortly, at the beginning of droplet/particle falling in the coolant. Following such a V-shaped evolution in velocity, the droplet/particle slows down gradually to a comparatively steady velocity. An increase in either coolant temperature or droplet temperature results in a larger velocity variation in the “J-region”, but a smaller deceleration when it moves out of the “J-region”. The elevated volatility of a coolant leads to a steeper deceleration in the “J-region” and beyond. The bigger size of a particle leads to a greater velocity variation in the “J-region” and terminal velocity. A high melting point and thermal conductivity as well as lower heat capacity contribute to dramatic variation in the “J-region” and low terminal velocity.

关键词： dynamic characteristics     molten droplets     high-temperature particles     fuel and coolant interactions    

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Numerical solution, simulation and testing of the thermal dynamic characteristics of ball-screws

XIA Junyong, HU Youmin, WU Bo, SHI Tielin

《机械工程前沿（英文）》 2008年 第3卷 第1期   页码 28-36 doi: 10.1007/s11465-008-0007-4

摘要： This research focuses on the characteristics of how a ball-screw changes its temperature corresponding to the periodic change of the end-most heat source. Based on the theory of heat transfer, this paper supplies a numerical solution to the non-homogeneous equation of heat transfer through the group explicit (GE) finite difference approach. The temperature distribution for the ball-screw at different times and directions is shown. By simulating and modeling the temperature field and thermal deformation of the ball-screw under periodically varying heat sources, this paper describes the thermal dynamic characteristics of the ball-screw under such conditions. By testing the thermal dynamic characteristics of the ball-screw, the numerical solution is validated.

关键词： numerical solution     temperature corresponding     temperature distribution     end-most     ball-screw    

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Biochars derived from carp residues: characteristics and copper immobilization performance in water environments

《环境科学与工程前沿（英文）》 2023年 第17卷 第6期 doi: 10.1007/s11783-023-1672-6

摘要：

● P-rich carp residues-derived biochars presented excellent Cu sorption capacity.

关键词： Biowaste     Pyrolytic temperature     Immobilization     Bioavailability     Remediation    

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Crystallization and viscosity-temperature characteristics during co-gasification of industrial sludge

Linmin ZHANG, Bin LIU, Juntao WEI, Xudong SONG, Yonghui BAI, Jiaofei WANG, Ying ZHOU, Huijun YANG, Guangsuo YU

《能源前沿（英文）》 2022年 第16卷 第6期   页码 1037-1047 doi: 10.1007/s11708-022-0824-x

摘要： Co-gasification of industrial sludge (IS) and coal was an effective approach to achieve harmless and sustainable utilization of IS. The long-term and stable operation of a co-gasification largely depends on fluidity of coal-ash slag. Herein, the effects of IS addition on the crystallization and viscosity of Shuangmazao (SMZ) coal were investigated by means of high temperature stage coupled with an optical microscope (HTSOM), a scanning electron microscopy coupled with an energy dispersive X-ray spectrometry (SEM-EDS), X-ray diffraction (XRD), a Fourier transform infrared spectrometer (FTIR), and FactSage software. The results showed that when the proportion of IS was less than 60%, with the addition of IS, the slag existed in an amorphous form. This was due to the high content of SiO2 and Al2O3 in SMZ ash and blended ash, which had a high glass-forming ability (GFA). The slag formed at a high temperature had a higher polymerization degree and viscosity, which led to a decrease in the migration ability between ions, and ultimately made the slag difficult to crystallize during the cooling. When the proportion of IS was higher than 60%, the addition of IS increased the CaO and FeO content in the system. As network modifiers, CaO and FeO could provide O2− at a high temperature, which reacted with silicate network structure and continuously destroyed the complexity of network structure, thus reducing the polymerization degree and viscosity of slag. At this time, the migration ability between ions was enhanced, and needle-shaped/rod-shaped crystals were precipitated during the cooling process. Finally, the viscosity calculated by simulation and Einstein-Roscoe empirical formula demonstrated that the addition of IS could significantly improve the fluidity of coal ash and meet the requirements of the liquid slag-tapping gasifier. The purpose of this work was to provide theoretical support for slag flow mechanisms during the gasifier slagging-tapping process and the resource treatment of industrial solid waste.

关键词： co-gasification     industrial sludge     crystallization     viscosity     mineral matter evolution    

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Performance and emission characteristics of QHCCI dimethyl ether engine

WANG Ying, LI Wei, ZHOU Longbao, LIU Shenghua, HU Tiegang

《能源前沿（英文）》 2008年 第2卷 第4期   页码 401-405 doi: 10.1007/s11708-008-0075-5

摘要： Experimental investigation into the effects of different pilot amounts of dimethyl ether (DME) on the performance and emission of a single-cylinder direct-injection DME engine is conducted. The results show that a DME engine can operate at a wider range of speeds and loads at quasi-homogenous charge compression ignition (QHCCI) mode. The brake thermal efficiency increases while the exhaust temperature decreases. NO emission decreases by about 30%–50% although there is a slight increase in HC and CO emissions. NO, HC and CO emissions increase with an increase in the amount of DME pilot. QHCCI is a good way to increase thermal efficiency and decrease NO emission.

关键词： Experimental investigation     single-cylinder direct-injection     exhaust temperature     dimethyl     compression ignition    

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Effect of anisotropic characteristics on the mechanical behavior of asphalt concrete overlay

Lingyun YOU, Zhanping YOU, Kezhen YAN

《结构与土木工程前沿（英文）》 2019年 第13卷 第1期   页码 110-122 doi: 10.1007/s11709-018-0476-4

摘要： Asphalt concrete (AC) overlays placed over old asphalt pavement have become an alternative to repairing and reinforcing pavements. The strength contributed by the AC overlay is strongly influenced by the anisotropic properties of the pavement material. This study was conducted to analyze the influence of anisotropy, modulus gradient properties, and the condition of the AC overlay and old pavement contact plane on the mechanical behaviors of AC overlays, as well as to quantify the influence of the degree of anisotropy on the mechanical behaviors of AC overlay by a sensitivity analysis (SA). The mechanical behaviors of the AC overlay were numerically obtained using the three-dimensional finite element method with the aid of ABAQUS a commercial program. Variations in the AC overlay’s modulus as a function of temperature as well as the contact state between the AC overlay and AC layer were considered. The SA is based on standardized regression coefficients method. Comparing the mechanical behavior in terms of surface deflection, stress, and strain of the anisotropy model against those corresponding to the isotropic model under static loads show that the anisotropic properties had greater effects on the mechanical behavior of the AC overlay. In addition, the maximum shear stress in the AC overlay was the most significant output parameter affected by the degree of anisotropy. Therefore, future research concerning the reinforcement and repair of pavements should consider the anisotropic properties of the pavement materials.

关键词： asphalt concrete overlay     anisotropy     temperature gradients     modulus gradients     finite element simulation     sensitivity analysis    

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典型高温地热系统——羊八井热田基本特征

多吉

《中国工程科学》 2003年 第5卷 第1期   页码 42-47

摘要：

羊八井热田是属于陆陆碰撞板缘非火山型高温地热田。热田是由3个不同能的热储层构成，即浅层、深部第一和第二热储层，实质上它们属同一个水力系统，是一个完整的地热系统的不同部位。浅层热储由第四系松散沉积物及部分基岩风化壳构成，其埋深在地表以下180～280 m，热储温度130～173℃，水质类型为C1--HCO3--Na+型水，属深部热流体与冷水混合的产物，流体以液相为主。深部热储由变质杂岩体中的滑离断层系构造空间构成，属基岩裂隙型脉状或带状热储，其中深部第一热储埋深为950～1 350 m，最高温度259.6 ℃；深部第二热储位于1 850 m深，热储最高温度可达329.8 ℃，深部热流体水质类型均属C1--Na+ 型，气体组份中CO2占主导地位。

关键词： 高温地热     热储层     成因     羊八井     西藏    

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Transversal tube pitch effects on local heat transfer characteristics of the flat tube bank fin mountedvortex generators and their sensitivity to nonuniform temperature of the fin

Liangbi WANG, Zhimin LIN, Kangjie SUN, Yuanxin DONG, Song LIU, Yongheng ZHANG,

《能源前沿（英文）》 2010年 第4卷 第3期   页码 333-345 doi: 10.1007/s11708-009-0061-6

摘要： The tube bank fin is commonly used to increase the area of the heat transfer surface with a small heat transfer coefficient of a heat exchanger. If vortex generators (VGs) are punched on the fin surface, the heat transfer performance of the fin can be improved. This paper focused on the effect of transversal tube pitch on the local heat transfer performance of the three-row flat tube bank fin mounted with VGs. On the fin surface, constructing the flow channel but without mounted VGs, the transversal tube pitch was greater, and the span averaged Nusselt number downstream was larger because fewer interactions of vortices would be generated from different VGs located upstream. When the area goodness factor was used as the criteria on the condition of one tube unit of heat exchanger for commonly used fin materials and fin thickness, the transversal tube pitch has considerable effect on the heat transfer enhancement of VGs. Large transversal tube pitch is more sensitive to fin material than to fin thickness.

关键词： heat transfer enhancement     vortex generator     finned flat tube bank     heat exchanger    

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Industrial-scale investigations on effects of tertiary-air declination angle on combustion and steam temperaturecharacteristics in a 350-MW supercritical down-fired boiler

Xiaoguang LI, Lingyan ZENG, Hongye LIU, Yao LI, Yifu LI, Yunlong ZHAO, Bo JIAO, Minhang SONG, Shaofeng ZHANG, Zhichao CHEN, Zhengqi LI

《能源前沿（英文）》 2021年 第15卷 第1期   页码 132-142 doi: 10.1007/s11708-020-0803-z

摘要： Industrial-scale experiments were conducted to study the effects of tertiary air declination angle (TDA) on the coal combustion and steam temperature characteristics in the first 350-MW supercritical down-fired boiler in China with the multiple-injection and multiple-staging combustion (MIMSC) technology at medium and high loads. The experimental results indicated that as the TDA increased from 0° to 15°, the overall gas temperature in the lower furnace rose and the symmetry of temperature field was enhanced. The ignition distance of the fuel-rich coal/air flow decreased. In near-burner region, the concentration of O decreased while the concentrations of CO and NO increased. The concentration of NO decreased in near-tertiary-air region. The carbon in fly ash decreased significantly from 8.40% to 6.45% at a load of 260 MW. At a TDA of 15°, the ignition distances were the shortest (2.07 m and 1.73 m) at a load of 210 MW and 260 MW, respectively. The main and reheat steam temperatures were the highest (557.2°C and 559.4°C at a load of 210 MW, 558.4°C and 560.3°C at a load of 260 MW). The carbon in fly ash was the lowest (4.83%) at a load of 210 MW. On changing the TDA from 15° to 25°, the flame kernel was found to move downward and the main and reheat steam temperatures dropped obviously. The change of TDA has little effect on NO emissions(660–681 mg/m at 6% O ). In comprehensive consideration of the pulverized coal combustion characteristics and the unit economic performance, an optimal TDA of 15° is recommended.

关键词： supercritical down-fired boiler     industrial-scale experiment     tertiary air declination angle     coal combustion     steam temperature    

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Thermal analysis of lubricated three-dimensional contact bodies considering interface roughness

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0672-8

摘要： Surface roughness and thermal action are of remarkable importance in the lubrication performance of mechanical components, especially in extreme conditions. However, available studies mainly focus on the full-film lubrication conditions without considering temperature rise and real 3D surface roughness due to the complexity of surface topography and temperature characteristics. Moreover, studies on the interfacial thermal behaviors of 3D rough surface lubricated contact in an extended range of working conditions remain limited. In this paper, a deterministic mixed thermal elastohydrodynamic lubrication model considering real 3D surface roughness and thermal effects is proposed. In this model, pressure and temperature are coupled with each other, the computation of elastic deformation is accelerated through the discrete convolution and fast Fourier transform method, the temperature field is calculated with the column sweeping technique, and the semi-system method is introduced to improve convergence and numerical stability under severe conditions. The model is validated by comparing its results with available published numerical and experimental results. The thermal behaviors of the contact interface are studied in a wide range of working conditions. The influences of surface roughness and thermal effect on lubrication performance are revealed. The results show that the proposed model can be used as a powerful analysis tool for lubrication performance and temperature prediction in various heavy-load, high-speed lubricated components over a wide range of lubrication conditions.

关键词： thermal elastohydrodynamic lubrication     surface roughness effect     thermal effect     temperature characteristics     severe conditions    

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CFD Simulation of thermal hydraulic characteristics in a typical upper plenum of RPV

Mingjun WANG, Lianfa WANG, Yingjie WANG, Wenxi TIAN, Jian DENG, Guanghui SU, Suizheng QIU

《能源前沿（英文）》 2021年 第15卷 第4期   页码 930-945 doi: 10.1007/s11708-021-0728-1

摘要： A comparative computational fluid dynamics (CFD) study was conducted on the three different types of pressurized water reactor (PWR) upper plenum, named TYPE 1 (support columns (SCs) and control rod guide tubes (CRGTs) with two large windows), TYPE 2 (SCs and CRGTs without windows), and TYPE 3 (two parallel perforated barrel shells and CRGTs). First, three types of upper plenum geometry information were collected, simplified, and adopted into the BORA facility, which is a 1/5 scale system of the four-loop PWR reactor. Then, the geometry, including the upper half core, upper plenum region, and hot legs, was built using the platform. After that, an unsteady calculation to simulate the reactor balance operation at hot full power scenario was performed. Finally, the differences of flowrate distribution at the core outlet and temperature distribution and transverse velocity inside the hot legs with different upper plenum internals were compared. The results suggest that TYPE 1 upper plenum internals cause the largest flowrate difference at the core outlet while TYPE 3 leads to the most even distributed flowrate. The distribution and evolution pattern of the tangential velocity inside hot legs is highly dependent on the upper plenum internals. Two counter-rotating swirls exist inside the TYPE 1 hot leg and only one swirl revolving around the hog leg axis exist inside the TYPE 2 hot leg. For TYPE 3, two swirls like that of TYPE 1 rotating around the hot leg axis significantly increase the temperature homogenization speed. This research provides meaningful guidelines for the future optimization and design of advanced PWR upper plenum internal structures.

关键词： pressurized water reactor (PWR)     upper plenum     internal structures     temperature distribution     computational fluid dynamics (CFD)    

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Numerical simulation of combustion characteristics at different coal concentrations in bituminous coal

Chunlong LIU, Qunyi ZHU, Zhengqi LI, Qiudong ZONG, Yiquan XIE, Lingyan ZENG

《能源前沿（英文）》 2013年 第7卷 第2期   页码 255-262 doi: 10.1007/s11708-013-0255-9

摘要： With the objective of producing a full-scale tiny-oil ignition burner, identical to the burner used in an 800 MWe utility boiler, numerical simulations were performed using Fluent 6.3.26 to study the progress of ignition for four coal concentration settings covering sub-operation conditions prevailing during the experiments performed with the burner. The numerical simulations conformed to the experimental results, demonstrating the suitability of the model used in the calculations. Simulations for a coal concentration of 0.40 kg/kg corresponding to a single burner operating at its rated output were also conducted, which indicated that gas temperatures along the burner centerline were high. As gas flowed to the burner nozzle, the high-temperature region expanded, ensuring a successful pulverized-coal ignition. With increasing coal concentration (0.08–0.40 kg/kg), the gas temperature along the burner centerline and at the first and second combustion chamber exits decreased at the equivalent radial points. At the center of the second combustion chamber exit, the O concentrations were almost depleted for the five coal concentrations, while the CO concentrations peaked.

关键词： numerical simulation     tiny-oil ignition burner     pulverized coal     temperature field    

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Characteristics and application of road absorbing solar energy

Zhihua ZHOU, Shan HU, Xiaoyan ZHANG, Jian ZUO

《能源前沿（英文）》 2013年 第7卷 第4期   页码 525-534 doi: 10.1007/s11708-013-0278-2

摘要： If the heat of road surface can be stored in summer, the road surface temperature will be decreased to prevent permanent deformation of pavement. Besides, if the heat stored is released, it can supply heat for buildings or raise the road surface temperature for snow melting in winter. A road-solar energy system was built in this study, and the heat transfer mechanism and effect of the system were analyzed according to the monitored solar radiant heat, the solar energy absorbed by road and the heat stored by soil. The results showed that the road surface temperature was mainly affected by solar radiation, but the effect is hysteretic in nature. The temperature of the solar road surface was 3°C–6°C lower than that of the ordinary road surface. The temperature of the solar road along the vertical direction was 2°C–5°C lower than that of the ordinary road. The temperature difference increased as the distance to the heat transfer tubes decreased. The average solar collector efficiency of the system was 14.4%, and the average solar absorptivity of road surface was 36%.

关键词： solar energy     road-solar energy system     road surface temperature     solar absorptivity of road surface     solar collector efficiency of system    

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Recent progress in hydrodynamic characteristics research and application of annular centrifugal extractors

《化学科学与工程前沿（英文）》 2022年 第16卷 第6期   页码 854-873 doi: 10.1007/s11705-022-2156-0

摘要： The annular centrifugal extractor (ACE) integrates mixing and separation. It has been widely used in many industrial fields because of its low residence time, compact structure, and high mass transfer efficiency. Most of the literature has focused on flow instabilities, flow visualization, and computational fluid dynamics simulations. More recently, research on hydrodynamic behavior and structural optimization has received widespread attention. With the development of ACE technology, applications have been broadened into several new areas. Hence, this paper reviews research progress regarding ACE in terms of hydrodynamic characteristics and the structural improvements. The latest applications covering hydrometallurgy, nuclear fuel reprocessing, bio-extraction, catalytic reaction, and wastewater treatment are presented. We also evaluate future work in droplet breakup and coalescence mechanisms, structural improvements specific to different process requirements, scaling-up methods, and stability and reliability after scaling-up.

关键词： annular centrifugal extractor     hydrodynamic characteristics     structure optimization     the latest application    

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Clinical characteristics and outcomes of biopsy-proven diabetic nephropathy

null

《医学前沿（英文）》 2017年 第11卷 第3期   页码 386-392 doi: 10.1007/s11684-017-0574-z

摘要：

Kidney damage is common in patients with diabetes mellitus (DM). However, whether the type of kidney damage can be reliably diagnosed using clinical data alone remains unclear. Predictive factors for diabetic nephropathy (DN) outcomes are also poorly understood. In this study, the clinical manifestations of 111 cases of biopsy-proven DN were described, and the clinical and pathological parameters of patients with different DN outcomes were compared. Results showed that long DM duration (>10 years in 32.4% of patients), severe proteinuria (62.2%), and renal dysfunction (estimated glomerular filtration rate [eGFR]<60 mL/(min·1.73 m2)) (52.3%) did not accurately indicate whether the condition of these patients progressed to DN. Hematuria (48.6%) failed to specify either DN or nondiabetic renal disease. Diabetic retinopathy (78.4%) was a crucial complication in patients with DN. Kaplan–Meier analysis revealed that the renal survival of 53 patients who were diagnosed with DN and were followed up was not significantly associated with glomerular classification (P>0.05). Cox’s regression analysis demonstrated that renal survival time was significantly influenced by sex (b= 1.394, P= 0.038), hematuria (b= 0.036, P= 0.029), and eGFR (b= −0.039, P= 0.002) but was not significantly affected by age, 24 h urinary protein excretion, or glomerular classification (P>0.05). In conclusion, the clinical characteristics of DN vary, and renal biopsy is necessary to determine renal damage patterns. Sex, hematuria, and the eGFR may affect DN outcomes, whereas the glomerular classification may not.

关键词： diabetic nephropathy     clinical characteristics     renal biopsy     outcomes    

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标题 作者 时间 类型 操作

Dynamic characteristics of molten droplets and hot particles falling in liquid pool

Liangxing LI, Weimin MA, Huixiong LI, Tingkuan CHEN,

期刊论文

Numerical solution, simulation and testing of the thermal dynamic characteristics of ball-screws

XIA Junyong, HU Youmin, WU Bo, SHI Tielin

期刊论文

Biochars derived from carp residues: characteristics and copper immobilization performance in water environments

期刊论文

Crystallization and viscosity-temperature characteristics during co-gasification of industrial sludge

Linmin ZHANG, Bin LIU, Juntao WEI, Xudong SONG, Yonghui BAI, Jiaofei WANG, Ying ZHOU, Huijun YANG, Guangsuo YU

期刊论文

Performance and emission characteristics of QHCCI dimethyl ether engine

WANG Ying, LI Wei, ZHOU Longbao, LIU Shenghua, HU Tiegang

期刊论文

Effect of anisotropic characteristics on the mechanical behavior of asphalt concrete overlay

Lingyun YOU, Zhanping YOU, Kezhen YAN

期刊论文

典型高温地热系统——羊八井热田基本特征

多吉

期刊论文

Transversal tube pitch effects on local heat transfer characteristics of the flat tube bank fin mountedvortex generators and their sensitivity to nonuniform temperature of the fin

Liangbi WANG, Zhimin LIN, Kangjie SUN, Yuanxin DONG, Song LIU, Yongheng ZHANG,

期刊论文

Industrial-scale investigations on effects of tertiary-air declination angle on combustion and steam temperaturecharacteristics in a 350-MW supercritical down-fired boiler

Xiaoguang LI, Lingyan ZENG, Hongye LIU, Yao LI, Yifu LI, Yunlong ZHAO, Bo JIAO, Minhang SONG, Shaofeng ZHANG, Zhichao CHEN, Zhengqi LI

期刊论文

Thermal analysis of lubricated three-dimensional contact bodies considering interface roughness

期刊论文

CFD Simulation of thermal hydraulic characteristics in a typical upper plenum of RPV

Mingjun WANG, Lianfa WANG, Yingjie WANG, Wenxi TIAN, Jian DENG, Guanghui SU, Suizheng QIU

期刊论文

Numerical simulation of combustion characteristics at different coal concentrations in bituminous coal

Chunlong LIU, Qunyi ZHU, Zhengqi LI, Qiudong ZONG, Yiquan XIE, Lingyan ZENG

期刊论文

Characteristics and application of road absorbing solar energy

Zhihua ZHOU, Shan HU, Xiaoyan ZHANG, Jian ZUO

期刊论文

Recent progress in hydrodynamic characteristics research and application of annular centrifugal extractors

期刊论文

Clinical characteristics and outcomes of biopsy-proven diabetic nephropathy

null

期刊论文