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Mini-hydrocyclones in water: state-of-the-art

Green Chemical engineering 2024年

作者： Liu, Lin Sun, Yian Zhao, Lixin Wang, Yahong Kleinmeyer, Zeth Yang, Qinghai Rosso, Diego School of Mechanical Science and Engineering Northeast Petroleum University Daqing163318 China Department of Civil & Environmental Engineering University of California IrvineCA92697-2175 United States Water-Energy Nexus Center University of California IrvineCA92697-2175 United States Heilongjiang Key Laboratory of Petroleum and Petrochemical Multiphase Treatment and Pollution Prevention Daqing163318 China State Key Laboratory of Continental Shale Oil Daqing163318 China PetroChina Research Institute of Petroleum Exploration & Development Beijing100083 China

A mini-hydrocyclone (MHC) is known for its higher separation efficiency, particularly for fine or ultra-fine particles. However, the exact mechanism for enhancing the separation efficiency of MHCs has not been fully elucidated. This literature review fills the existing gap by comprehensively reviewing characteristics of the flow field inside MHCs, metrics of separation performance, applicable research methods, influence of physical and operating parameters, and provides references for future design and applications. Among them, the metrics of separation performance include grade separation efficiency, total separation efficiency, cut size, pressure drop, separation sharpness, and the fish hook effect, etc. This is the first time to comprehensively review the differences between MHCs and conventional hydrocyclones (CHCs) based on the above characteristics and metrics and analyze the separation advantages of MHCs. The fluid in MHC exhibits larger centrifugal acceleration, poor symmetry of tangential velocity, higher proportion of the wall friction loss, more obvious amplitude of partial sway of the air core, and smaller ratio of the locus of zero vertical velocity height to the total length of MHC. Challenges and further work on MHCs are also discussed in terms of potential applications and needed improvements. © 2024 Institute of Process engineering, Chinese Academy of Sciences.

关键词： flow fields

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Two-phase distributor in plate fin heat exchanger

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Huagong Xuebao/CIESC Journal 2011年第SUPPL. 1期62卷 31-36页

作者： Yuan, Pei Jiang, Guobao Zhang, Feini He, Yaling Tan, Minbang Tao, Wenquan School of Energy and Power Engineering State Key Laboratory of Multi-phase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi China Company Jianyang 641400 Sichuan China

The maldistribution of two-phase flow is one of the major factors that deteriorate the heat transfer performance of plate-fin heat exchanger. The set-up of flow distributor at the heat exchanger inlet is one widely adopted engineering method to improve the flow distribution. In this paper the flow distribution performance of one type of distributor is experimentally tested by using air-water mixture. The test results show that the flow distributor studied can improve the two-phase flow distribution uniformity in plate-fin heat exchanger. © All Rights Reserved.

关键词： Two phase flow

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Numerical simulation on filling process of drag reduction agent in natural gas pipeline

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Journal of Physics: Conference Series 2021年第1期1985卷

作者： Xiaoyun Yin Jiaqiang Jing Peiyu Jing Jie Sun Ying Yuan School of Oil & Natural Gas Engineering Southwest Petroleum University Chengdu China Oil & Gas Fire Protection Key Laboratory of Sichuan Province Chengdu China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

In this paper, a numerical simulation is established to model the filling process of atomized natural gas drag reduction agent (DRA) at the pipeline inlet section. The computations are on the basis of the Euler-Lagrange method with the standard k-ε turbulence model. The effects of atomizing parameters on the droplets Sauter Mean Diameter (SMD) and the adsorption performance on the wall of pipe are investigated using the validated model. The results show that nozzle diameter and nozzle angle have little effect on the SMD of DRA droplets, whereas the size of the droplets SMD reduces with the increase of atomizing pressure, and the influence of atomizing flow rate is just the opposite.

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Thermal management matters in photovoltaic–electrocatalysis for solar hydrogen production

EcoEnergy

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EcoEnergy 2024年

作者： Jie Chen Xin Chen Jie Sun Jingkuo Qu Xiangjiu Guan Shaohua Shen School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

Photovoltaic–electrolysis (PV-EC) system currently exhibits the highest solar to hydrogen conversion efficiency (STH) among various technical routes. This perspective shifts the focus from the materials exploration in photovoltaics and electrolysis to the critical aspect of thermal management in a PV-EC system. Initially, the theoretical basis that elucidates the relationships between temperature and the performance of both photovoltaics and electrolyzers are presented. Following that, the impact of thermal management on the performance of PV-EC for solar hydrogen production is experimentally demonstrated by designing variables-controlling experiments. It is observed that while utilizing identical PV and EC cells under varying thermal conditions, the highest STH can reach 22.20%, whilst the lowest is only 15.61%. This variation underscores the significance of thermal management in optimizing PV-EC systems. Finally, increased efforts to enhancing heat transfer and optimizing heat distribution are proposed, thus facilitating the design of more efficient PV-EC systems with minimized thermal energy losses.

关键词： device design photovoltaic-electrolysis solar to hydrogen thermal management water electrolyzer

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Improve the Conversion Rate and Selectivity of Aromatic Monomers in Lignin Photocatalytic Conversion Reaction Via Phase Junction Cadmium Sulphide Nanoparticles and External Hydrogen Supplier

SSRN

引用

SSRN 2023年

作者： Yue, Zongyang Shao, Shibo Yu, Jialin Lu, Guanchu Wei, Wenjing Huang, Yi Zhang, Kai Wang, Ke Fan, Xianfeng Institute for Materials and Processes School of Engineering The University of Edinburgh EdinburghEH9 3BF United Kingdom Petrochemical Research Institute PetroChina Company Limited Beijing102206 China Beijing Key Laboratory of Ionic Liquids Clean Process CAS Key Laboratory of Green Process and Engineering State Key Laboratory of Multiphase Complex Systems Innovation Academy for Green Manufacture Institute of Process Engineering Chinese Academy of Sciences Beijing100190 China Longzihu New Energy Laboratory Zhengzhou Institute of Emerging Industrial Technology Henan University Zhengzhou450000 China Beijing Key Laboratory of Emission Surveillance and Control for Thermal Power Generation North China Electric Power University Beijing102206 China

Photocatalysis has the potential for lignin valorisation to generate functionalised aromatic monomers, but its large-scale application has been limited by the slow conversion rate and the low selectivity to desirable products. In this work, record-high lignin model compound Cβ-O bonds cleavage rate and excellent selectivity to aromatic monomers has been achieved over the development of new hexagonal-cubic phase junction CdS nanoparticles, enhanced external hydrogen donor supply and hydrogen transfer, and improved separation efficiency of photo-excited electron-hole pairs. Water is employed as external hydrogen supplier, resulting in significant increase in the conversion rate of 2-Phenoxy-1-phenylethanol (PP-ol) as lignin model from 21.8% to 100% and the selectivity of aromatic monomers from ~45% to ~94% under 1h of visible light irradiation. 2-phenoxyacetophenone (PP-one) as by-product from PP-ol conversion can be further completely cleaved to aromatic monomers with assistance of TEA and reaction time is reduced from 2-12 hrs to10 min under visible-light irradiation. © 2023, The Authors. All rights reserved.

关键词： Lignin

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Convective heat transfer of air flow in cold cabinet with two-fluid model

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Huagong Xuebao/CIESC Journal 2012年第SUPPL.1期63卷 138-144页

作者： Wei, Min Wang, Limin State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

The convective heat transfer of the cold cabinet was investigated by using two-fluid model after the effectiveness of new model was confirmed. This study includes the influence of wind speeds, wind directions and speeds of air curtain. The results show that the convective heat transfer is improved along with increasing of the wind speed. In a relatively short time, there is a linear relationship between convective heat transfer and time. The wind direction has small effect on heat transfer when it is less than about 15° while has appreciable impact and made an increase of energy consumption by approximately 30% when it reaches 30°. The air curtain, a major constituent of the refrigeration system of cold cabinet, provides a barrier of moving air across a door opening and reduces heat transfer by preventing the penetration of hot air. The simulation shows that there is the minimum speed and the best speed range of air curtain. The air curtain can not be formed when the speed is less than 1.5 m·s-1, while has a large spillover of cold air when it is greater than 3.0 m·s-1. From the above, the best speed of air curtain ranges from 2.6 m·s-1 to 3.0 m·s-1.

关键词： Energy utilization

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Achieving ferroelectricity in a centrosymmetric high-performance semiconductor by strain engineering

arXiv

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arXiv 2023年

作者： Wu, Mengqi Lou, Zhefeng Dai, Chen-Min Wang, Tao Wang, Jiaqi Zhu, Ziye Xu, Zhuokai Sun, Tulai Li, Wenbin Zheng, Xiaorui Lin, Xiao Key Laboratory of 3D Micro/nano Fabrication and Characterization of Zhejiang Province School of Engineering Westlake University Zhejiang Province Hangzhou310024 China Key Laboratory for Quantum Materials of Zhejiang Province Department of Physics School of Science Westlake University Hangzhou310030 China Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application School of Physical Science and Technology Suzhou University of Science and Technology Suzhou215009 China Center for Electron Microscopy State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology College of Chemical Engineering Zhejiang University of Technology Hangzhou310014 China

Phase engineering by strains in 2D semiconductors is of great importance for a variety of applications. Here, we present a study of strain induced ferroelectric (FE) transition on bismuth oxyselenide (Bi2O2Se) films, a high-performance (HP) semiconductor for next-generation electronics. Bi2O2Se is non-FE at ambient. Upon a loading force & 400 nN, piezoelectric force responses exhibit butterfly loops on magnitude and 180o phase switching. By carefully ruling out extrinsic factors, these features are attributed to a transition to FE phase. The transition is further proved by the appearance of a sharp peak on optical second harmonic generation under an uniaxial strain. Fundamentally, solids with paraelectric at ambient and FE under strains are scarce. FE transition is discussed with the help of first-principle calculations and theoretical simulations. The switching of FE polarization acts as a knob for Schottky barrier engineering at contacts and serves as basis for a memristor with a huge switching ratio of 106. Our work endows a new degree of freedom to a HP electronic/optoelectronic semiconductor and the integration of FE and HP semiconductivity paving the way for multiple exciting functionalities, including HP neuromorphic computation and bulk piezophotovoltaic. Copyright © 2023, The Authors. All rights reserved.

关键词： Degrees of freedom (mechanics)

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Phase difference effect on collective locomotion of two tandem autopropelled flapping foils

引用

Physical Review Fluids 2019年第5期4卷 054101-054101页

作者： Xingjian Lin Jie Wu Tongwei Zhang Liming Yang Department of Aerodynamics Nanjing University of Aeronautics and Astronautics Yudao Street 29 Nanjing Jiangsu 210016 China Key Laboratory of Unsteady Aerodynamics and Flow Control Ministry of Industry and Information Technology Nanjing University of Aeronautics and Astronautics Yudao Street 29 Nanjing Jiangsu 210016 China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Yudao Street 29 Nanjing Jiangsu 210016 China Department of Mechanical Engineering National University of Singapore 10 Kent Ridge Crescent Singapore 119260

The effect of phase difference on the collective locomotion of two tandem flapping foils is numerically studied in this paper. The numerical results indicate that the collective locomotion is greatly affected by the phase difference. Two distinct collective modes are observed, i.e., the fast mode and the slow mode. The fast mode is only observed in part of the range of the phase difference (ϕ), i.e., ϕ=0.0−0.1π and 1.5π–1.9π with appropriate initial distance, and the slow mode appears in the range of ϕ=0.3π−1.4π. Meanwhile, the follower of the two foils has hydrodynamic benefit in both fast and slow modes, and it can obtain the highest efficiency in the fast mode at ϕ=1.6π. However, the leader can only achieve hydrodynamic benefit in the fast mode, and the highest efficiency occurs at ϕ=0.1π. In addition, the stable distance between two foils in the slow mode can be quantized with the phase difference. Furthermore, the fluid-structure interactions between two foils are also analyzed. Two distinct vortex interactions are observed in the fast mode, i.e., merging interaction and broken interaction, which, respectively, result in the highest propulsive efficiency for the follower and the leader. In the merging interaction, the leading edge vortex of the leader is captured by the follower, which results in the weak trailing edge vortex of the leader but a strong trailing edge vortex of the follower. In the broken interaction, the leading edge vortex of the follower sheds into the wake together with the trailing edge vortex of the leader, and induces the trailing edge vortex of the follower to be broken into two parts. Which kind of vortex interaction occurs depends on the phase difference. The results obtained here may provide some light on understanding the coordinated behavior of biological collectives.

关键词： Locomotion Immersed boundary methods Navier-Stokes equation

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Au [email protected] @ZnIn 2 S 4 nanosheets with significantly enhanced visible-light photocatalytic H 2 evolution: The effect of different Au positions on the transfer of electron-hole pairs

引用

Applied Catalysis B: Environmental 2021年 282卷

作者： Siman Mao Jian-Wen Shi Guotai Sun Dandan Ma Chi He Zengxin Pu Kunli Song Yonghong Cheng State Key Laboratory of Electrical Insulation and Power Equipment Center of Nanomaterials for Renewable Energy School of Electrical Engineering Xi'an Jiaotong University Xi'an 710049 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi China

Herein, a new type of photocatalysts, Au [email protected] @ZnIn 2 S 4 nanosheets ( [email protected] @ZIS), is elaborately designed for the photocatalytic H 2 evolution from water splitting, where Au nanodots (NDs) are anchored in the pore space of thiol-functionalized UiO66 metal-organic framework (MOF) and ZnIn 2 S 4 nanosheets are wrapped around the UiO66 MOF containing Au NDs. It is found that the different Au positions have a grateful effect on the transfer of photogenerated charge carriers. In [email protected] @ZIS, the photoexcited electrons transfers from ZnIn 2 S 4 to UiOS and then to Au NDs, establishing a smooth transmission channel of electrons. As expected, the optimal sample (Au 4 @ [email protected] 40 ) presents a high photocatalytic H 2 production rate of 391.6 μmol/h (10 mg of catalyst) under visible light irradiation, which is 435.1, 61.2 and 10.2 times higher than that of the pure UiOS, ZnIn 2 S 4 and [email protected] , respectively.

关键词： Photocatalysis Hydrogen evolution Metal-organic framework Thiol- functionalization Au nanodots

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Stall-Induced Aeroelastic Instability of Floating Offshore Wind Turbines

SSRN

引用

SSRN 2023年

作者： Meng, Qingshen Yu, Wei Wu, Faming Hua, Xugang Chen, Chao State Key Laboratory of Bridge Engineering Safety and Resilience College of Civil Engineering Hunan University Changsha410082 China Wind Energy Section Flow Physics and Technology Faculty of Aerospace Engineering Delft University of Technology Kluyverweg 1 Delft2629HS Netherlands CRRC Zhuzhou Electric Locomotive Research Institute Co. Ltd. Zhuzhou412000 China

With the trend of the increasing size of Floating Offshore Wind Turbines (FOWTs), the issue of stall-induced aeroelastic instability has become a great concern. This study employs a nonlinear aeroelastic finite element (FE) model and a linearized one to investigate the instability phenomenon when an OC3 5MW FOWT is parked and misaligned with the wind direction. Linear eigenvalue analysis indicates that the blades, platform, and tower structures all exhibit the potential for instability caused by stall at certain Angle of Attacks (AOAs). However, the presence of hydrodynamic damping on the platform substantially mitigates its instability risk, resulting in higher overall damping ratios. Nonlinear time domain simulation shows that the aerodynamic negative damping effect on the blades results in Limit Cycle Oscillations (LCOs) of blades which is manifested by the coupled edgewise-flapwise motion of blades. Additionally, blade instability may introduce high-frequency vibrations on platform DOFs with limited negligible amplitudes. Finally, beyond the instability arising from their own negative damping characteristics, tower structures also experience notable oscillations due to the instability of blades. © 2023, The Authors. All rights reserved.

关键词： Stability

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