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Flocculation of suspended cohesive particles in Rayleigh-Bénard turbulence

Physical Review Fluids 2025年第2期10卷 024305-024305页

作者： Han Huang Shuaiqi Zhao Rui Zhang Binbin Pei Kunpeng Zhao Bofeng Bai State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Key Laboratory of Mechanics on Disaster and Environment in Western China The Ministry of Education of China Lanzhou University Lanzhou 730000 China

We employ a four-way coupled numerical approach to investigate the dynamics of suspended cohesive particles in Rayleigh-Bénard turbulence. The Stokes drag, cohesive, and direct contact forces between primary particles are captured in detail, yielding the phenomena of flocs' aggregation, breakage, and deformation. The momentum and thermal exchange between primary particles and the fluid are considered based on the Source-in-Cell method. We found that the initial increase of the average floc size indicates a temporary flocculation phase, which is followed by an equilibrium phase where the average floc size becomes stable, reflecting the balance between aggregation and breakage. Different from the traditional perspective, which attributed the local accumulation of particles to their gravity, we found that the suspended particles still tend to accumulate in the bottom hot boundary layer region. This accumulation is primarily driven by the temperature-induced variation in aggregation strength and the nonuniform spatial distribution of floc inertia. Additionally, the stronger cohesion yields a reduction in momentum intensity of the thermal plumes, primarily due to the more pronounced weakening of fluid momentum by the larger flocs.

关键词： Momentum

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Experimental and modeling investigation of zero net liquid flow in hilly terrain pipeline

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Petroleum Science 2025年第5期22卷 2183-2202页

作者： Huang, Bo Xu, Qiang Chang, Ying-Jie Cao, Ye-Qi Yu, Hai-Yang Li, Yu-Wen Guo, Lie-Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China College of Petroleum Engineering Xi'an Shiyou University Shaanxi 710065 China

Hilly terrain pipeline is a common form of pipeline in oil and gas storage and transportation industry. Due to the hilly terrain influence, the liquid at the elbow of the gathering pipeline is easy to flow back and accumulate to form slug flow, so it is necessary to remove the accumulated liquid by gas purging. In this paper, experiment is carried out in hilly terrain pipelines. Three flow patterns of stratified flow, slug flow and stratified entrained flow are observed. The process of gas purging accumulated liquid is divided into four stages, namely liquid accumulation, liquid rising, continuous outflow and tail outflow. At the same time, the flow pattern maps of each stage are drawn. The pressure drop signal is analyzed in time domain and frequency domain, and the contour map of pressure drop distribution is drawn. It is found that the ratio of range to average value can well distinguish the occurrence range of each flow pattern. Based on visualization, the transition process of slug flow to stratified flow and stratified entrained flow is studied, and the transition boundary prediction model is established. An image processing method is proposed to convert the image signal into a similarity curve, and PSD analysis is performed to calculate the slug frequency. The normal distribution is used to fit the slug frequency, and the predicted correlation is in good agreement with the experimental data. © 2025 The Authors

关键词： Optical flows

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Experimental study on the thermochemical reduction of supercritical CO2 by guaiacol

Experimental study on the thermochemical reduction of superc...

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International Multidisciplinary Conference on Computer and Energy Science (SpliTech)

作者： Yimeng Wei Jiadela Kuanibieke Hui Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University China

The continuous growth of CO 2 emissions is one of the global problems facing humanity, and how to convert and exploit the stock of CO 2 has become an urgent issue. Biomass as an activity of CO 2 thermal reduction medium has become the focus of human attention in general. Supercritical CO 2 (SCCO 2 ) has the advantages of near-liquid density and high solubility, which can further strengthen the reduction process (T≥31.26℃, P≥72.9 atm). This paper described a SCCO 2 reduction method of guaiacol on an intermittent Kettle Reactor to investigate the effects of reaction temperature (400-700℃), residence time (5-20 min) and reactant concentration (4 wt%-16wt%) on the three-phase products. The experimental results indicated that the carbon gasification efficiency (CE) and hydrogen gasification efficiency (HE) were 43.7% and 56.7%, respectively, when the carbon dioxide consumption reached 16.15 mol/kg. As the temperature increased, the consumption of carbon dioxide increased and the concentration of reactants increased with opposite results.

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Enhancing the Frequency Control Stability in Large-Scale VPPs with Limited Capacity of Fast-Response Units 19th

Enhancing the Frequency Control Stability in Large-Scale VPP...

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19th Annual Conference of China Electrotechnical Society, ACCES 2024

作者： Liang, Jun Tian, Zeyu Zhang, Penghua Zhang, Mingyue Li, Wei Liu, Huan Chong, Daotong China Nuclear Power Operation Technology Co. Ltd. Hangzhou311215 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China China Nuclear Power Operation Management Co. Ltd. Jiaxing314300 China

ISBN: (纸本)9789819647996

As renewable energy penetration increases, Virtual power Plants (VPPs) must not only manage energy scheduling but also ensure system security, particularly in response to frequency fluctuations. Existing research focuses on optimizing Primary Frequency Control (PFC) and developing specific control strategies for VPP units. In this study, a dynamic simulation model of a VPP was constructed, and two control systems—Energy Management System (EMS) and Capacity Coordinated Frequency Control (CCFC)—were established and optimized for better control effectiveness. The results demonstrate that the EMS designed for rapid energy storage response is better than traditional methods in responding frequency disturbances caused by rapid power demand changes. Under EMS control, the frequency nadir improved by 17.5%, and the time to reach steady-state was reduced by 77.2% during rapid power increases. Similarly, the nadir improved by 17.1%, and the steady-state time was reduced by 69.5% during power decreases. In addition, the coordinated optimization of EMS and CCFC enhances the VPP’s ability to manage large-scale power fluctuations. The safe power step adaptation range is expanded from 5 MW to 25 MW when the BESS’s dispatchable power is limited. This study highlights the potential of integrated control strategies to significantly enhance the frequency regulation and overall stability of VPPs. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Frequency stability

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PROCESS MODELING AND ECONOMIC VIABILITY ANALYSIS OF A power-TO-H2-TO-power SYSTEM: CASE STUDY IN CHINA 37

PROCESS MODELING AND ECONOMIC VIABILITY ANALYSIS OF A POWER-...

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37th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2024

作者： Li, Yanxin Dai, Yanbing Han, Xiaoqu Guo, Xuanhua Karellas, Sotirios Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China Qingdao Huaru Energy Technology Company Limited Qingdao China Laboratory of Steam Boilers and Thermal Plants National Technical University of Athens 9 Heroon Polytechniou str. Zografou Greece

ISBN: (纸本)9798331307660

The power sector generates the most significant greenhouse gas emissions in many countries, while renewable energy penetration faces a bottleneck due to its ***, it is imperative to make substantial efforts to promote the penetration of renewable energy sources into the power *** process of hydrogen production with renewable energy sources is becoming increasingly economical as the cost of renewable energy sources, particularly onshore wind, has fallen *** the present work, a power-to-H2-to-power system (PHPS) combining onshore wind power was proposed as a solution for high penetration of renewable energy, which incorporates a large-scale alkaline water electrolyzer, and a gas turbine.A techno-economic study based on NOVO PRO© and GT PRO was carried out and applied to cases in Shaanxi, *** performance and operational characteristics of two types of PHPS with different hydrogen storage methods, PHPS/Tank and PHPS/Cavern, were *** is indicated that when 30% of the fuel of the gas turbine was replaced by hydrogen, the levelized cost of energy (LCOE) of the PHPS/Cavern was 0.0498 €/kWh with an internal rate of return (IRR) of 6.41%, therefore, PHPS/Cavern was economically feasible in ***, the renewable energy utilization and carbon reduction benefits of the PHPS were *** surplus electricity (curtailed electricity) and carbon emissions of the PHPS/Cavern can be decreased by 52% and 12%, respectively, compared to those of PHPS without hydrogen as the energy *** performance of PHPS with different hydrogen substitution ratios was *** analysis was further conducted to investigate the influence of key parameters on the system performance, including wind modules investment, electrolyzer investment, transport distance, and electricity ***, under the future scenarios in China in 2050, the LCOE of PHPS/Cavern can be reduced by 15% as well as the IRR increased by 66%.The result

关键词： Hydrogen storage

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Homojunction photocatalysts for water splitting

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Nano Research 2022年第12期15卷 10171-10184页

作者： Xiangjiu Guan Shichao Zong Shaohua Shen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an710049China Suzhou Academy of Xi’an Jiaotong University Suzhou215123China Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region Ministry of EducationSchool of Water and EnvironmentChang’an UniversityXi’an710064China

Charge-carrier separation is regarded as one of the critical issues of photocatalytic water splitting and could be accelerated by constructing microscopic junctions in *** photocatalysts consisting of different forms of semiconductor with identical compositions could inherit the advantages of heterojunction-based photocatalysts in charge separation due to the built-in electric field,while omitting the potential drawbacks of interfacial lattice distortion by providing continuous band ***,homojunction-based photocatalysts have recently drawn growing attention in water *** this review,the synthetic approaches to preparing photocatalysts with various homojunction structures including p-n junction,phase junction,and facet junction were introduced,together with a comprehensive analysis and discussion on the latest progress in the application of photocatalytic water *** review work is expected to inspire more related work with promoted research on designing efficient homojunction-based photocatalytic systems for water splitting.

关键词： photocatalytic water splitting homojunction charge separation

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Simulation Study on Heat Exchangers Characteristics of Solar Thermal Steam System Based on Aspen Plus 2

Simulation Study on Heat Exchangers Characteristics of Solar...

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2nd International Conference on Algorithms, High Performance Computing and Artificial Intelligence, AHPCAI 2022

作者： Chen, Pengfei Chen, Kang Peng, Huaiwu Zhang, Yanlong Bawaa, Baercheng Zhao, Qiuyang Institute of Solar Engineering Technology Northwest Engineering Corporation Limited Power China Xi'an710065 China Xi'An Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an China

ISBN: (纸本)9798350334784

In the thermal recovery project of thick oil, there are high standards for steam temperature and flow rate. The solar thermal steam supply system can convert unstable solar energy into stable and efficient carrier heat, which can be used to transfer heat to low-temperature water to produce high-temperature steam and achieve a clean and low-carbon steam supply. The rated pressure of steam and the split ratio of molten salt in the heating system have a great influence on the demand area and heat load of solar panels. In this paper, a simulation is made on the solar thermal steam supply system based on Aspen Plus. The simulation result shows that the increase in pressure will cause a growth in the area of the photothermal concentrator field but will reduce the area used for photovoltaic panels. At the same time, it reduces the heat load of the evaporator and extends its service life. The split ratio affects the molten salt temperature at the outlet of the superheater and the reheater. When the split ratio increases, the heat transfer temperature difference between the two ends of the superheater heat flow decreases, and the heat transfer temperature difference of the reheater grows bigger. Therefore, the molten salt temperature flowing out of the reheater rises. © 2022 IEEE.

关键词： Heat exchangers

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Regulation on polymerization degree and surface feature in graphitic carbon nitride towards efficient photocatalytic H2 evolution under visible-light irradiation

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Journal of Materials Science & Technology 2022年第3期98卷 160-168页

作者： Cheng Cheng Chung-Li Dong Jinwen Shi Liuhao Mao Yu-Cheng Huang Xing Kang Shichao Zong Shaohua Shen International Research Center for Renewable Energy(IRCRE) State Key Laboratory of Multiphase Flow in Power Engineering(MFPE)Xi'an Jiaotong University(XJTU)28 West Xianning RoadXi’an 710049China Department of Physics Tamkang University151 Yingzhuan RoadTamsui 25137TaiwanChina

A kind of graphitic carbon nitride(TSC-550) with high polymerization degree and improved surface property was prepared by a new precursor of thiosemicarbazide. The sulfur motif and high nitrogen content in thiosemicarbazide promoted the polymerization of thiosemicarbazide to form graphitic carbon nitride framework with high degree of polymerization, which significantly influenced the electronic structure and surface chemical properties. TSC-550 possessed a narrow bandgap of 2.19 eV that facilitated the utilization of visible light, and possessed a less positive charge, acidic surface that resulted in enhanced hydrogen adsorption ability in water solution, which promoted the H;evolution kinetics. In addition, the extended π-conjugated electronic system promoted the separation and migration of photogenerated charge carries in plane of TSC-550 framework, as well as the increasing interlayer C–N interactions in TSC-550 created conductive paths across the layers to tunnel interlayers for rapid electron transportation. As a result, TSC-550 nanosheets showed excellent photocatalytic H;production activity,the AQY achieved 36.4% at 425 nm.

关键词： Degree of polymerization Graphitic carbon nitride Photocatalysis Solar energy Hydrogen

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Development of low-cost, large-scale green H2 production/power generation and large capacity long-term energy storage

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Science China Technological Sciences 2025年第9期68卷 1-12页

作者： Guo, Liejin Guan, Yonggang Jin, Hui State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China Engineering Thermophysics and Energy Utilization Discipline of National Natural Science Foundation of China Beijing China

Renewable energy, such as solar energy, wind energy, and hydraulic energy, mostly belongs to process energy, which is hard to store, while fossil energy belongs to energy-carrier energy, which can achieve long-term storage. Current conversion and utilization technologies for all types of energy mainly focus on power generation. Fossil energy is convenient to store, but its conversion and utilization technologies mainly rely on the combustion of fossil fuels for power and thermal energy generation, emitting huge amounts of pollutants and CO2. power and thermal energy are still process energy which is hard to be stored, and the problem of the low-cost, efficient and long-term storage of energy is difficult to solve, which is the fundamental deficiencies of the current energy production and supply system. H2 as an energy-carrier energy enables both clean and efficient use and storage. Therefore, the development of efficient, low-cost, large-scale green H2/power generation is imperative. It is recommended that: (1) new renewable energy units be developed based on integrating H2, thermal energy and power energy poly-generation technology on demand. The already built “sole power generation” renewable energy units should be transformed into H2, thermal energy and power energy poly-generation model, to build a comprehensive energy multi-link supply system that achieves energy storage, transportation and utilization, as well as the full-time, high-efficiency, low-cost conversion and utilization of renewable energy. (2) Developing low-carbon and clean technologies for green H2 and power from carbon-based energy sources, achieving efficient energy conversion and full utilization of resources. (3) Building a new industry for high-value conversion and high-quality utilization of fossil fuels to produce the high-value chemical products instead of pollutants which also provides the best solution for large-capacity and long-term energy storage.

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A n-Si/CoOx/Ni:CoOOH photoanode producing 600 mV photovoltage for efficient photoelectrochemical water splitting

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Science China Materials 2022年第12期65卷 3442-3451页

作者： Zhuocheng Yin Yuchuan Shi Shaohua Shen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049China

n-Si,believed as a promising photoanode candidate,has suffered from sluggish oxygen evolution reaction(OER)kinetics and poor chemical stability when exposed to aqueous ***,CoO_(x)/Ni:CoOOH bilayers were successfully deposited on n-Si substrate by atomic layer-deposition(ALD)and photoassisted electrochemical deposition(PED)for stabilizing and catalyzing photoelectrochemical(PEC)water *** comparison to the n-Si/CoO_(x)photoanode as reference,the prepared n-Si/CoO_(x)/Ni:CoOOH photoanode upon the optimized PED process presents a much improved PEC performance for water splitting,with the onset potential cathodically shifted to~1.03 V *** hydrogen electrode(RHE)and the photocurrent density much increased to 20 mA cm^(−2)at 1.23 V *** is revealed that the introduction of Ni dopants increases the work functions of the deposited Ni:CoOOH overlayers,which gives rise to the upward band bending weakened at the n-Si/CoO_(x)/Ni:CoOOH cascading interface while strengthened at the Ni:CoOOH/electrolyte interface(with the band bending shifted from downward to upward),contributing to the decreased and the increased driving forces for charge transfer at the interfaces,***,the balanced driving forces at the interfaces would endow the n-Si/CoO_(x)/Ni:CoOOH photoanode with the best PEC ***,PED has been evidenced superior to ED to dope Ni into CoOOH with the formed overlayer effectively catalyzing and stabilizing PEC water splitting.

关键词： n-Si photoanode work function photoelectrochemical water splitting

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