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SSRN 2024年

作者： Tang, Sanli Gai, Zhongrui Li, Yang Liu, Yunlian Liu, Mingkai Pan, Ying Jin, Hongguang Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing100190 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China University of Chinese Academy of Sciences Beijing100049 China

Chemical looping methane reforming has emerged as a promising avenue to produce blue hydrogen. Among the various oxygen carriers investigated for this process, Fe2O3 and NiO have garnered significant attention due to their affordability and favorable thermodynamic properties. Usually, such oxygen carriers had satisfactory H2 yields only in the oxidation stage with temperatures over 800 °C. This limitation poses challenges for industrial reactor design and product gas separation. In this study, we present a nanoscale Fe/Ni bimetallic oxygen carrier for dual-stage hydrogen generation from mid-temperature chemical looping methane reforming. The lab-scale oxygen carrier can produce H2 in both the reduction and the oxidation steps, reaching 75% overall H2 purity while reducing the temperature to 500-600 °C. Moreover, the 10-kg scale oxygen carrier achieved >90% CH4 conversion, >78% H2 purity and 2.8-3.5 H2 molecules produced per CH4 molecule. Made into beads, the 10-kg scale oxygen carrier still maintained an outlet H2 purity of >70% with redox stability over 150 cycles. These findings contribute to the advancement of chemical looping methane reforming for blue hydrogen production and supply. © 2024, The Authors. All rights reserved.

关键词： Hydrogen production

Novel Fast Predesign Methodology of Centrifugal Compressor Used for Pemfcs Based on 1d Loss Mechanism and Interpretable Machine Learning Models

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SSRN 2024年

作者： Chen, Zhikai Sun, Jieshuai Chen, Ziying Spence, Stephen Peng, Xueyuan Feng, Jianmei School of Energy and Power Engineering Xi'an Jiaotong University Xi'An710049 China School of Mechanical Manufacturing and Biomedical Engineering Trinity College Dublin Dublin 2 Ireland State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China

The significant challenge of balancing accuracy, time, and cost has consistently compelled designers to develop more efficient and economical predesign methods. To tackle this issue, a novel predesign method amalgamating one-dimensional (1D) loss model with gradient boosting decision tree (GBDT) model has been proposed. A high-precision 1D loss model was developed and experimentally tested for rapid performance assessment. Furthermore, two machine learning models, named Extreme Gradient Boosting (XGBoost) and Light Gradient Boosting Machine (LightGBM), were trained, and compared to construct surrogate models. Hyperparameter optimization was executed utilizing a Bayesian algorithm to identify the optimal hyperparameter set. Additionally, the Sobol sensitivity analysis and Shapley Additive Explanations (SHAP) based interpretability were used to explore the paramount factors affecting the model's outputs and the interactions among the sensitive parameters. The findings underscore that the blade outlet angle, impeller outlet diameter, impeller outlet width, inlet shroud diameter, and blade inlet angle(shroud) are the most five important parameters influencing the model's indexes. Some beneficial design guidelines are distilled from their feature importance and interactions. and The implement of new design yields powerful evidence for the developed prior knowledge with an increase of 2.5830% in isentropic efficiency and a reduction of 1.5202% in power consumption. © 2024, The Authors. All rights reserved.

关键词： Sensitivity analysis

A Three-Dimensional Curve Interface Reconstruction Algorithm for Two-Phase Fluid flow

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SSRN 2024年

作者： Chen, Yujie Gong, Junhua Sun, Dongliang Han, Dongxu Wang, Peng Yu, Bo Tao, Wen-Quan School of Mechanical Engineering Beijing Institute of Petrochemical Technology Beijing102617 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Key Laboratory of Thermo–Fluid Science and Engineering Ministry of Education School of Energy & Power Engineering Xi’an Jiaotong University Shaanxi 710049 China

The curve interface reconstruction algorithm has received significant attention in the context of two-dimensional two-phase flow. However, it remains absent in the three-dimensional scenario. This paper proposes a novel three-dimensional curve interface reconstruction (CIR) algorithm to address this challenge within structured meshes for the first time. Specifically, a portion of the spherical surface is employed to reconstruct the three-dimensional curve interface segment, with the radius and center coordinates determined by curvature and mass conservation constraints, respectively. To enhance curvature accuracy, a sphere-based iterative reconstruction (SIR) algorithm is proposed to calculate the reconstructed distance function (RDF) for the three-dimensional curve interface. Various tests involving the reconstruction and interface capture of spherical, ellipsoidal, and cubic objects demonstrate that the coupled SIR and CIR (SIR-CIR, simplified by SCIR) method achieves high accuracy, particularly with coarse mesh resolutions. Additionally, the SCIR method offers the advantages of straightforward implementation and coding for interface reconstruction in two-phase flow research. This advantage results in reduced computational costs compared to the coupled volume-of-fluid and level set (VOSET) method, which also utilizes an iterative method to solve RDF. © 2024, The Authors. All rights reserved.

关键词： Spheres

Dynamics of two-dimensional water flow in angstrom-scale mono and hybrid channels

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Physical Review Fluids 2024年第12期9卷 124201-124201页

作者： Chengzhen Sun Qiyuan Wang Mehdi Neek-Amal Runfeng Zhou Bofeng Bai State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China Department of Physics Shahid Rajaee Teacher Training University 16875-163 Lavizan Tehran Iran Departement Fysica Universiteit Antwerpen Groenenborgerlaan 171 B-2020 Antwerpen Belgium

We investigate the dynamics of two-dimensional (2D) water flow within angstrom-scale channels (ASCs), a domain scarcely explored in nanofluidics. Our study focuses on the transformation of monolayer water through hybrid channels made of graphene and MoS2, as well as channels where both walls are made of either graphene or MoS2, with sizes ranging from 6 to 8 Å. We find that the transport of monolayer water through ASCs is significantly hindered under low-pressure conditions at nanoscale timescales. To comprehensively explore the flow dynamics, we introduce a refined extension of the Hagen-Poiseuille equation that accounts for frictional slippage dynamics. Our results indicate that hybrid channels exhibit lower flux compared to monochannels. These findings provide valuable insights into the 2D flow mechanisms of monolayer water molecules, highlighting their distinctive interactions with channel walls and unique structural properties.

关键词： flow confinement Nanofluidics Molecular dynamics Navier-Stokes equation

Research of Cooling Tower Filler Based on Radial Basic Function Artificial Neural Network (Rbf Ann)

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SSRN 2022年

作者： Chen, Jie Zhang, Lixin Zhao, Shunan Chen, Yongbao Song, Huijuan Liu, Jingnan Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China China Institute of Water Resources and Hydropower Beijing100038 China

The filler is the core component of a cooling tower for heat dissipation. The empirical formulas of N, β xv , and ΔP are constitute the performance of filler. In certain conditions, the formulas are obtained by experiments. Performance equations for identical countercurrent fillers are different at varying heights or seawater concentrations. The conventional method is linear interpolation to obtain the filler performance under different conditions. But its uncertainty limits the application of the performance equation to some extent. Therefore, the RBF ANN is adopted to analyze the filler performance based on the existing performance equations in this paper. The dataset is generated by the filler performance equations. The results show that RBF ANN has a preferable prediction effect of filler performance with high correlation (R>0.99) and prediction accuracy (N 10 >90%). In addition, the trend of the predicted results and the experimental results of the filler performance is consistent. Therefore, RBF ANN can accurately predict the filler performance at different heights and different seawater concentrations, which provides the basis for the design of cooling towers. © 2022, The Authors. All rights reserved.

关键词： Cooling towers

Study of Saturated Pool Boiling Heat Transfer Characteristics of R1233zd(E) on Aluminum-Based Micro-Pin Finned Surfaces

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SSRN 2024年

作者： Yang, Xiaoping Bu, Shichao Jiang, Zhuye Chen, Hongqiang Sun, Zhen Zhang, Yonghai Wei, Jinjia School of Chemical Engineering and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Mobile Network and Mobile Multimedia Technology ZTE Corporation hillsides China

With the continuous development of chip integration and information technology, the heat dissipation has become a major limitation on the performance of electronic devices such as 5G base station, data center and so on, and meanwhile a challenge of conventional single-phase convection cooling methods. Boiling is prospective in high heat flux cooling and energy saving due to the usage of latent heat. R1233zd(E), an environmentally friendly refrigerant (GWP=1, ODP=0) with a freezing point of -107°C, is a potential working fluid in phase-change heat sinks for geographical applications. Nevertheless, the poor boiling performance of R1233zd(E) on plain surface due to the limitation in thermophysical properties must be enhanced. Moreover, conventional heat sinks are mostly copper-based, which are inconvenient for transportation and installation, and costly for production as well. In this work, micro pin fins in the range of 100-500 μm are fabricated on the aluminum surface to enhance the pool boiling of R1233zd(E). Moreover, the influence of their size and saturation pressure on the bubble behavior, critical heat flux (CHF) and heat transfer coefficient (HTC) is experimentally and theoretically investigated. The results show that the increase of pressure, as well as the ensuing various nucleation site and capillary effect to rewet the evaporation region, can lead to an increase in the CHF and HTC. Notably, the 150-200 μm micro pin-finned surfaces reaches the highest CHF and 100 μm one owns the highest HTC, which is 214% and 383% higher than that of plain surface, respectively. BY considering the balance of capillary effect and bubble convolution effect, a model of CHF is proposed to reveal the mechanism of optimum size of the micro pin fins. The predicted CHFs have an inaccuracy of less than ±20% comparing to experimental values. This paper makes up for the lack of basic experimental data on pool boiling of R1233zd(E) on aluminum surface, which thus provides guidance for

关键词： Heat flux

Corrosion Effect Analysis on Thermal-Hydraulics of Lbe/Water Spiral Tube Steam Generator Under Oxygen-Controlled Environment

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SSRN 2023年

作者： Lu, Dingsheng Yang, Yupeng Wang, Chenglong Zhang, Dalin Qiao, Pengrui Tian, Wenxi Qiu, Suizheng Su, Guanghui H. School of Nuclear Science and Technology Shanxi Key Laboratory of Advanced Nuclear Energy and Technology Xi'an Jiaotong University Xi'An710049 China China Institute of Atomic Energy Beijing102413 China State Key Laboratory of Multiphase Flow in Power Engineering China

In order to explore the flow and heat transfer characteristics of spiral tube steam generators under Lead-Bismuth Eutectic (LBE) corrosion, the accelerated removal effect of LBE corrosion flow was perfected, and a bidirectional coupling model of LBE corrosion and flow heat transfer was established. Computational fluid dynamics (CFD) method was used to simulate the corrosion and flow heat transfer of helical tube steam generator under saturated oxygen concentration and oxygen-controlled environment. The results indicate that the corrosion of liquid LBE forms an oxidation layer, which hinders the heat transfer in the spiral tube steam generator. This leads to a significant increase in the wall friction coefficient and a decrease in the surface Nusselt number. However, it does not have a significant effect on the water side evaporation process of the spiral tube steam generator. The implementation of an oxygen-controlled environment can effectively reduce the influence of LBE corrosion on the flow heat transfer of the spiral tube steam generator. Especially under high temperature conditions, it can reduce the near wall temperature of LBE change by up to 57.5% and the outlet temperature change by up to 61.5%. The oxygen-controlled environment results in prolonged local hypoxia time, with a more pronounced effect at higher temperatures. © 2023, The Authors. All rights reserved.

关键词： Oxygen

Efficient Charge Transfer at the Donor-Bridge-Acceptor Interface for Excellent Supercapacitors

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SSRN 2023年

作者： Yin, Baoyi Hao, Liang Li, Xiaogan Yang, Qi-Guo Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China School of Microelectronics Dalian University of Technology Dalian116024 China

The intrinsic electrochemical activity and active sites of the battery-like electrode in supercapacitors originate from efficient charge transfer at the interface. A seamless all-carbon graphdiyne layer on CoNi2S4 yolk-shell spheres (CoNi2S4/GDY YSSs) provides a unique structure of a flawless "donor–bridge–acceptor" interface, where Ni atoms and Co atoms serve as electron donors and acceptors, respectively, connected by the sp-C–Ni and sp-C–Co bonds as bridges. Importantly, this particular can facilitate effective electron transfer from the Ni atoms to the Co atoms, resulting in more interfacial Co2+ active sites. Additionally, the seamless all-carbon graphdiyne layer greatly enhances the structural and interfacial stabilities of CoNi2S4 yolk-shell spheres, effectively avoiding structural deterioration. Profiting from its structural merits, the CoNi2S4/GDY YSSs electrode delivers a considerable capacitance of 856 C/g at 1 A/g, along with exceptional rate capability (61.9% for 50-fold current density increase). Furthermore, an asymmetric supercapacitor with the CoNi2S4/GDY YSSs electrode cathode achieves a remarkable maximum energy density of 91.7 Wh/kg at a power density of 793 W/kg. Furthermore, the strategy proposed in this study has the potential to open up new pathways for the battery-like electrode design with realistic supercapacitor applications. © 2023, The Authors. All rights reserved.

关键词： Charge transfer

Connectivity control of effective sorption capacity and kinetics in heterogeneous porous media

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Connectivity control of effective sorption capacity and kine...

第一届全国水处理与回用学术会议

作者： Li Wang Hang Wen Li Li Department of Environmental Science and Engineering State Key Laboratory of Multiphase Flow in Power Department of Energy and Mineral Engineering Penn State UniversityUniversity ParkPA 16802USA Department of Civil and Environmental Engineering Penn State UniversityUniversity ParkPA 16802USA

This work examines the effects of spatial heterogeneity in regulating Cr(Ⅵ)sorption under different geostatistical characteristics and spatial scale *** flow-through experiments in heterogeneous columns of 0.1 meters have shown that sorption in heterogeneous media can be characterized by three effective quantities: sorption capacity(Csc,m),early-stage fast sorption rate(kc1),and late-stage slow sorption rate(kc2).Two-dimensional reactive transport models are developed by calibrating these data from these columns of different illite distribution patterns and permeability contrasts between illite and quartz *** models were further run in geostatistical fields of different permeability variance(σ2lnκ,0.2 and 4.5)and length scale(0.1 to 1.0 m)conditions to quantify their role in determining effective sorption capacity and *** results indicate that in highly-connected columns with high permeability variance and long s,Cr(Ⅵ)-containing flow travels mostly through the high permeability,non-sorbing quartz *** therefore occurs mostly at the illite-quartz *** capacity and early fast rates(kc1)therefore depend strongly on the connectivity and properties that control advective transport of the *** longer time scales,diffusive transport determines the late-stage slow rates(kc2)and the breakthrough tailing,which depend less on connectivity and more on the size of the low-permeability illite zones and transverse dispersivity α*** to homogeneous columns of the same illite content,highly-connected patterns can reduce effective sorption capacity by up to a factor of 6.7,fast sorption rates by a factor of 25.0,and slow sorption rate by a factor of more than 2.0 orders of *** the domain length increases,the effects of spatial heterogeneities on sorption capacity and early stage fast sorption rates diminish due to longer length scales for mixing;these effects however persist for the late-stage slow sorp

关键词： connectivity sorption capacity spatial heterogeneity length scales reactive transport modeling

Experiments and predictions for severe slugging of gas-liquid two-phase flows in a long-distance pipeline-riser system

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Ocean engineering 2024年 301卷

作者： Chang, Yingjie Xu, Qiang Zou, Suifeng Zhao, Xiangyuan Wu, Quanhong Wang, Yechun Thévenin, Dominique Guo, Liejin Shaanxi Key Laboratory of New Transportation Energy and Automotive Energy Saving Chang'an University Xi'an710064 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Laboratory of Fluid Dynamics and Technical Flows Otto-von-Guericke-Universität Magdeburg Magdeburg39106 Germany

Experiments concerning the flow regimes observed in gas-liquid two-phase flows in a long-distance pipeline-riser system were carried out and analyzed in this paper. The test loop with 0.075 m inner diameter consisted of a 314 m horizontal pipeline, followed by a 25 m downward-inclined pipe, and finally a 21.5 m riser pipe. An industrial-scale global flow regime map including 5 flow regimes was derived from differential pressure measurements in the riser and was used as a reference for improvements. Electrical capacitance volume tomography installed in the horizontal section was used to reconstruct the phase interface and calculate the average gas void fraction (GVF). An appropriate model for this system was selected by comparing the experimental GVF with different, widely used models. The occurrence of severe slugging flow (SS) can be predicted accurately using an improved model involving additional corrections that consider pipeline length, accurate GVF calculation, and gas density. This study supports the development of a suitable SS prediction model enabling safe design, operation, and control of practical systems. © 2024 Elsevier Ltd

关键词： Pipelines