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International Conference on Power engineering, ICOPE 2015

作者： Mu, Qiwei Han, Xiaoqu Wang, Bingqi Yan, Junjie Chen, Weixiong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Consisting of steam cooler, condensation zone and drain cooler, the three-stage feedwater heater is widely used in the thermal power plants. To study the variable condition characteristics of three-stage feedwater heater with water level controlled, a GSE simulation model of that in 300MW thermal system of power plant was established. Validated by the steady states of the heater, different dynamic characteristics were investigated when the load varied. The results revealed that the steam pressure, feedwater flow and feedwater inlet temperature drops would have a significant influence on the extracting steam flow, feedwater temperature increment and terminal temperature difference. The dynamic trends were intensified with the variation of the input condition enhanced. The response time of extracting steam pressure drops is 430s and that of feedwater flow drops would be prolonged to 600s. The dynamic processes with water level controlled were carried out and showed that adjusting flow valve could keep the water level stable and secure the operation of heater smooth and steady. However, frequently controlling the position of flow valve could impair the steady procedures of other parameters and prolonged the response time. © 2015 The Japan Society of Mechanical Engineers.

关键词： Water levels

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Simulation of dynamic fluid-solid interactions with an improved direct-forcing immersed boundary method

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Particuology 2015年第1期13卷 22-34页

作者： Shengbin Di Wei Ge State Key Laboratory of Multiphase Complex System Institute of Process EngineeringChinese Academy of Sciences University of Chinese Academy of Sciences

Dynamic fluid-solid interactions are widely found in chemical engineering, such as in particle-laden flows, which usually contain complex moving boundaries. The immersed boundary method （IBM） is a convenient approach to handle fluid-solid interactions with complex geometries. In this work, Uhlmann＇s direct-forcing IBM is improved and implemented on a supercomputer with CPU-GPU hybrid architec- ture. The direct-forcing IBM is modified as follows： the Poisson＇s equation for pressure is solved before evaluation of the body force, and the force is only distributed to the Cartesian grids inside the immersed boundary. A multidirect forcing scheme is used to evaluate the body force. These modifications result in a divergence-free flow field in the fluid domain and the no-slip boundary condition at the immersed boundary simultaneously. This method is implemented in an explicit finite-difference fractional-step scheme, and validated by 2D simulations of lid-driven cavity flow, Couette flow between two concentric cylinders and flow over a circular cylinder. Finally, the method is used to simulate the sedimentation of two circular particles in a channel. The results agree very well with previous experimental and numerical data, and are more accurate than the conventional direct-forcing method, especially in the vicinity of a moving boundary.

关键词： Immersed boundary method Fluid-solid interactions No-slip condition Divergence-free condition CPU-GPU hybrid architecture

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Thermal-diffusive instabilities of laminar premixed CH4/H2/air flat flames 10

Thermal-diffusive instabilities of laminar premixed CH4/H2/a...

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10th Asia-Pacific Conference on Combustion, ASPACC 2015

作者： Jin, Wu Wang, Jinhua Yu, Senbin Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

As one of the most promising clean alternative fuels, natural gas has been widely used in automobile engines. However, due to the slow burning velocity of natural gas and its poor lean-burn ability, hydrogen is often added to improve its combustion behavior. Researches on the fundamental laminar premixed flame characteristics of CH4/H2 blends are of great significance to understand the combustion process in practical combustors. The intrinsic instability of laminar flame is one of the classic issues in flame dynamics, which presents the dynamic response of laminar premixed flamelets to weak perturbations. By studying dynamic mechanism of intrinsic instability, we can estimate the burning velocity more accurately and gain a deeper insight into the turbulent combustion process in spark ignition engines. In this study, the cellular instabilities of laminar premixed CH4/H2/air flat flames were studied using McKenna burner with OH-PLIF technique. It was found that the addition of H2 can broaden the lean combustion limit on flat flame burner with which the cellular instabilities were brought. The digital and OH-PLIF images were obtained to calculate the quantitative parameters of cellular length scale, which is associated with the properties of fuel mixtures such as Lewis number, Markstein number et al. Through the theoretic analysis, we make a thorough investigation on the mechanism about how the cellular scales were determined.

关键词： Natural gas

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Modeling coal pyrolysis in a cocurrent downer reactor

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Particuology 2015年第4期13卷 154-159页

作者： Yan Zhang Yuehong Zhao Xianfeng He State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of Sciences University of Chinese Academy of Sciences

In this paper, a model for fast coal pyrolysis in a cocurrent downer reactor is developed, in which both hydrodynamics and coal pyrolysis kinetics are simultaneously considered. The results of simulations based on this model display reasonable agreement with experimental data obtained using Huolinhe coal as the feedstock, and this model is therefore suitable for predicting the fast pyrolysis of specific coal types. A series of simulations of fast coal pyrolysis in a cocurrent downer demonstrated that coal devolatilization is almost complete in the inlet region within a time span of 0.4 s, and that higher temperatures improve the pyrolysis efficiency. However, the yield of liquid products is decreased with increasing pyrolysis temperatures, especially above 670 ℃, because of additional cracking of the liquids.

关键词： Coal pyrolysis Model Cocurrent downer Low-rank coal

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Study on particle and photonic flux distributions in a magnetically stirred photocatalytic reactor

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Journal of Photonics for Energy 2015年第1期5卷

作者： Ren, Yuxun Jing, Dengwei Xi'An Jiaotong University International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering 28 Xianning West Road Xi'an Shaanxi710049 China

When dispersed in water, nanoscale photocatalysts can aggregate into microscale secondary particles due to their high surface energy. The interaction between the incident photons and the aggregated particles is expected to be significantly changed due to their comparable length scales. Hydrodynamics of the particles after aggregation and the resultant photonic flux distributions in slurry photocatalytic reactors are therefore essential. The magnetically stirred photocatalytic reactor is compact and simple for fabrication, and therefore can be readily employed in lab-scale photocatalytic tests. However, studies toward its optimization are rare. In our study, the photocatalyst distribution was simulated using a Eulerian-Lagrangian approach, while the evolution of free liquid surface led by magnetic stirring was modeled by volume of fluid method. Subsequently, based on the photocatalyst distribution, the photonic flux distribution was obtained through a mean free path-based Monte Carlo method. Outcomes suggest that at a stirring speed of 900 rpm, the 10 μm particles can be well suspended, and a moderate free liquid surface will also be present. Moreover, under sufficient stirring, larger catalyst particles are more likely to be densely distributed in the outer region, which contributes to an increase in the overall photonic absorption even higher than the one with evenly distributed photocatalysts. © The Authors.

关键词： Computational fluid dynamics

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A Supramolecular Crosslinker To Give Salt‐Resistant Polyion Complex Micelles and Improved MRI Contrast Agents

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Angewandte Chemie 2018年第39期130卷

作者： Jiahua Wang Junyou Wang Peng Ding Wenjuan Zhou Yuehua Li Markus Drechsler Xuhong Guo Martien A. Cohen Stuart State Key Laboratory of Chemical Engineering and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering East China University of Science and Technology 130 Meilong Road Shanghai 200237 P. R. China Institute of Diagnostic and Interventional Radiology The Sixth Affiliated People's Hospital Shanghai Jiao Tong University 600 Yi Shan Road Shanghai 200233 P. R. China Bavarian Polymer Institute (BPI) KeyLab of Electron and Optical Microscopy University Bayreuth Universitaetsstrasse 30 95440 Bayreuth Germany

Three‐component mixtures (diblock copolymer/metal ion/oligoligand) can assemble into micellar particles owing to a combination of supramolecular polymerization and electrostatic complex formation. Such particles cover a large range of compositions, but the electrostatic forces keeping them together make them rather susceptible to disintegration by added salt. Now it is shown how the salt stability can be tuned continuously by employing both a bis‐ligand and a tris‐ligand, and varying the ratio of these in the mixture. For magnetic ions such as Mn II and Fe III , the choice of the multiligand also affects the ion/water interaction and, hence, the magnetic relaxivity. As an example, Mn II ‐based nanoparticles with a very high longitudinal relaxivity (10.8 m m −1 s −1 ) were investigated that are not only biocompatible but also feature strong contrast enhancement in target organs (liver, kidney), as shown by T 1 ‐weighted in vivo magnetic resonance imaging (MRI).

关键词： Einstellbare Stabilität und Eigenschaften Kernspintomographie Kontrastmittel Koordinationspolymere Polyelektrolyt-Mizellen

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Smoothed particle hydrodynamics for coarse-grained modeling of rapid granular flow

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Particuology 2015年第4期13卷 173-178页

作者： Lijuan Deng Wei Wang Department of Chemical Engineering Ningbo University of Technology The EMMS Group State Key Laboratory of Multiphase Complex SystemsInstitute of Process EngineeringChinese Academy of Sciences

We simulated rapid flow in transient plane Couette flows of granular particles using the smoothed particle hydrodynamics （SPH） solutions of a set of continuum equations, This simulation was performed to test the viability of SPH in solving the equations for the solid phase of the two-fluid model associated with fluidization. We found that SPH requires the handling of fewer particles in simulating the collective behavior of rapid granular flow, thereby bolstering expectations of solving the equations for the solid phase in the two-fluid modeling of fluidization. Further work is needed to investigate the effect of terms describing pressure and viscous stress of solids on stability in simulations.

关键词： Smoothed particle hydrodynamics （SPH） Rapid granular flow Continuum model Two-fluid model Elastic modulus Transient plane Couette flow

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Flexible SERS active detection from novel Ag nano-necklaces as highly reproducible and ultrasensitive tips

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Science China Materials 2016年第6期59卷 435-443页

作者：段春阳任贝刘红缨王钰陈运法 State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical and Environmental Engineering China University of Mining and Technology(Beijing)Beijing 100083China

Surface-enhanced Raman scattering(SERS)spectroscopy has been considered as a promising way to realize real-time, in-situ and ultrasensitive analysis of chemoand biochemical molecules in different applications even in intracellular or aqueous environments. In this work, polymersupported novel Ag nano-necklaces(AgNLs) as flexible SERS substrates were fabricated for ultrasensitive chemical and biological detection. With the stringing of dense 'hot spot' in three-dimension, AgNLs located on polydimethylsiloxane(PDMS) work like the removable and reusable 'tip'on the surface of analytes with different morphologies and conditions. The novel substrate shows ultra-high enhancement factor(as high as 109) with excellent reproducibility and long-term stability(7 months) in an aqueous *** further functionalizing with p-mercaptobenzoic acid, AgNLs/PDMS elastomer also reveals sensitive and consistent pH detection ability over the wide range of pH4.0–9.0, indicating their wide applications in biological and environmental fields. This work provides a feasible strategy for designing ultrasensitive, reproducible and flexible SERS substrate for practical detection.

关键词： Ag nano-necklace SERS flexible substrate

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A Dental Glass without Leucite Crystals

A Dental Glass without Leucite Crystals

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The 24th International Conference on Glass( ICG Congress 2016 Shanghai) (第24届国际玻璃大会)

作者： L.Peng, Q.S.Zhu State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of SciencesBeijing 100190 China

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Numerical simulation of CO2-ionic liquid flow in a stirred tank

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Science China Chemistry 2015年第12期58卷 1918-1928页

作者： Zailong Ouyang Di Bao Xin Zhang Haifeng Dong Ruiyi Yan Xiangping Zhang Suojiang Zhang Beijing Key Laboratory of Ionic Liquids Clean Processing State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences College of Chemistry and Chemical Engineering University of Chinese Academy of Sciences

Ionic liquids(ILs) are new solvents that represent a breakthrough for absorption and conversion of CO2. However, there has been little research on the hydrodynamics of gas-IL systems in stirred tanks, and this has become a bottleneck for development of IL-based reactors. In the present study, a CO2-IL([bmim][BF4]) flow in a stirred tank was studied using computational fluid dynamics(CFD). A new drag coefficient model that is specific to a gas-ionic liquid system and a population balance model(PBM) were adopted to describe the bubble behavior, such as gas holdup and bubble size evolution, precisely. The predicted results for the total gas holdup and local Sauter diameter agree well with the experimental data. The influences of the gassing rate, agitation speed, and temperature on local gas holdup, bubble size distribution, and interfacial area for the CO2-[bmim][BF4] system were also investigated. The results of this study provide fundamental information for designing gas-IL systems for stirred tanks.

关键词： multiphase flow ionic liquids carbon dioxide stirred tank computational fluid dynamics population balance model

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