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Dense fluid transport through nanoporous graphene membranes in the limit of steric exclusion

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Physical Review Fluids 2024年第4期9卷 044202-044202页

作者： Runfeng Zhou Mathew M. Swisher Akshay Deshmukh Chengzhen Sun John H. Lienhard Nicolas G. Hadjiconstantinou Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China Center for Computational Science & Engineering Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA

We investigate transport of dense fluid flow through nanoporous membranes in the limit of steric exclusion using molecular dynamics (MD) and finite element simulations. Simulation results suggest that, for simple fluids, deviations from Sampson flow are a consequence of the competition between slip and finite atomic size effects. The latter manifest themselves by introducing an effective pore size, as well as an effective membrane thickness. We propose an analytical model for the membrane permeance that accounts for all these factors. We also show how this model can be modified to describe transport of low molecular weight aromatic hydrocarbons across these membranes in the steric limit. Extensive validation of this model is conducted through MD simulations of Lennard-Jones fluids permeating single- and multilayer graphene membranes, as well as low molecular weight organic liquids permeating single-layer graphene membranes.

关键词： Nanofluidics Finite-element method Molecular dynamics

Thermodynamic optimization of closed air Brayton cycle and air-ORC combined cycle

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Thermodynamic optimization of closed air Brayton cycle and a...

International Conference on Power Engineering 2021, ICOPE 2021

作者： Qian, Yiran Zhang, Zhuohua Yi, Jingwei Chen, Weixiong Liu, Ming Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Nuclear Power Institute of China Chengdu610213 China

In order to improve the flexibility and adaptability of small mobile nuclear power systems, air is considered as an optional working fluid of nuclear Brayton cycle system. It can avoid the shortage of working fluid under extreme conditions, and ensure the system operation with tight working fluid supply. In this study, simple regenerative cycle (SRC), intercooling regenerative cycle (IRC) and corresponding air-ORC combined cycle (SRCC and IRCC) are proposed and modeled. Thermodynamic analysis of key parameters is conducted. Genetic algorithm (GA) is applied for multi-parameter optimization to achieve the maximum cycle efficiency. With the increase of pressure ratio (PR), the efficiency of SRC increases firstly and then decreases. Pressure ratio corresponding to the maximum cycle efficiency increases gradually with turbine inlet temperature. The efficiency of IRC is slightly lower than that of SRC in low pressure ratio region, but IRC maintains a higher efficiency in high pressure ratio region. For SRCC, isobutane has the best performance among three selected organic working fluids. The multi-parameter optimization result indicates that the IRCC has lower cycle efficiency comparing with SRCC, and SRCC shows the optimal performance among the four configurations. © 2021 The Japan Society of Mechanical Engineers.

关键词： Efficiency

Experimental Study of an Aluminum Based Three-Dimensional Thermosyphon Heat Sink with Microscale Enhancement Structure

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SSRN 2024年

作者： Yang, Xiaoping Bu, Shichao Jiang, Zhuye Zhou, Yao 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

Heat dissipation is a significant factor limiting the advancement of electronics. Currently, air cooling remains the most widely used method for heat dissipation due to the advantages of low-cost and easy-maintenance. However, the traditional air-cooling method based on all-solid heat sink fails to meet the fast development in thermal power of electronics because its limitation in area expansion by only solid fins. In this study, an aluminum based three-dimensional thermosyphon (3D-TS) coupling boiling-condensation heat transfer and forced air cooling is proposed to overcome the limitation of conventional air cooling methods. Meanwhile, micro pin-fins structure is used to enhance the boiling heat transfer as well as the performance of the 3D-TS. Using the environmentally friendly refrigerant R1233zd(E) as working fluid, the performance of the 3D-TS is experimentally studied and analyzed under different air volume flow rates. The results show that the total thermal resistance decreases firstly and then increases with the heating power, which is mainly dominated by the boiling mode on the substrate. Moreover, the micro pin-fins greatly enhances the boiling heat transfer on the substrate of the 3D-TS, which enables the 3D-TS to reach a minimum thermal resistance of 0.075 K/W and a maximum thermal dissipating power of 650 W with the temperature of the heating source below 85 °C. The 3D-TS proposed in this work is able to meet the cooling requirements of most high-performance chips. This paper provides valuable reference and guidance for the design and optimization of the phase-change devices. © 2024, The Authors. All rights reserved.

关键词： Aluminum

Investigation on the Effect of Hydrothermal Reaction with Cuso4 on Rheological Property of Heavy Oil

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SSRN 2023年

作者： Zhou, Yantao Zhao, Qiuyang Wang, Xuetao Miao, Yan Song, Zhiwei Jin, Hui Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Xinjin Weihua Institute of Clean Energy Research Foshan528216 China

The rheological property is one of important physical properties evaluating heavy oil and asphalt. This work investigated the rheological changes during hydrothermal reaction with CuSO4. The results showed that the addition of CuSO4 at a high reaction temperature had an effect similar to asphalt modifiers, increasing the viscosity and elasticity. Further analysis suggested that the Cu atoms from CuSO4 entered heavy oil molecules, enhancing the interaction attraction between oil molecules. While, at a low reaction temperature, the CuSO4 acted as a catalyst, reducing both viscosity and elasticity. Based on these findings, this work proposed a novel and potential asphalt modification method, which changed the association effect between oil molecules by the chemical reaction to adjust the rheological properties permanently. This method would not fail due to the separation of modifiers and can adjust performance by changing reaction conditions. © 2023, The Authors. All rights reserved.

关键词： Transition metals

Bacterial Cellulose Composite Solid Polymer Electrolyte With High Tensile Strength and Lithium Dendrite Inhibition for Long Life Battery

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Energy & Environmental Materials 2021年第3期4卷 434-443页

作者： Yuhan Li Zongjie Sun Dongyu Liu Shiyao Lu Fei Li Guoxin Gao Min Zhu Mingtao Li Yanfeng Zhang Huaitian Bu Zhiyu Jia Shujiang Ding Department of Applied Chemistry School of ChemistryXi’an Key Laboratory of Sustainable Energy Materials ChemistryMOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterState Key Laboratory of Electrical Insulation and Power EquipmentXi’an Jiaotong UniversityXi’an 710049China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049China Department of Materials and Nanotechnology SINTEF IndustryForskningsveien 1Oslo 0373Norway School of Chemistry and Chemical Engineering MOE Key Laboratory of Cluster ScienceBeijing Institute of TechnologyBeijing 100081China

The development of metallic lithium anode is restrained by lithium dendrite growth during *** solid polymer electrolyte with high mechanical strength and lithium ion conductivity could be applied to inhibit lithium dendrite *** prepare the high-performance solid polymer electrolyte,the environment-friendly and cheap bacterial cellulose(BC)is used as filler incorporating with PEO-based electrolyte owing to good mechanical properties and Li salts ***/Li TFSI/BC composite solid polymer electrolytes(CSPE)are prepared easily by aqueous mixing in *** lithium ion transference number of PEO/Li TFSI/BC CSPE is 0.57,which is higher than PEO/Li TFSI solid polymer electrolyte(SPE)(0.409).The PEO/Li TFSI/BC CSPE exhibits larger tensile strength(4.43 MPa)than PEO/Li TFSI SPE(1.34 MPa).The electrochemical window of composite electrolyte is widened 1.43 V by adding *** functional theory calculations indicate that flex of PEO chains around Li atoms is suppressed,suggesting the enhanced lithium ion *** molecular orbitals results suggest that an unfavorable intermolecular charge transfer lead to achieve higher potential for BC composite *** solid-state Li metal battery with PEO/Li TFSI/BC CSPE delivers longer cycle life for 600 cycles than PEO/Li TFSI SPE battery(50 cycles).Li symmetrical battery using PEO/Li TFSI/BC CSPE could be stable for 1160 h.

关键词： all solid-state battery bacterial cellulose composite polymer electrolyte DFT calculations HOMO and LUMO

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

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

Numerical Investigation on Isolated Moving Charged Droplet Evaporation in Electrostatic Field with Highly Volatile R134a 15

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Numerical Investigation on Isolated Moving Charged Droplet E...

15th Triennial International Conference on Liquid Atomization and Spray Systems, ICLASS 2021

作者： Tian, Jiameng Wang, Junfeng Chen, Bin School of Energy and Power Engineering Jiangsu University Zhenjiang China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

Fundamental investigations of the charged droplet evaporation are helpful in enhancing the cooling capability and advancing the electrostatic spray model, whereas the corresponding data with the highly volatile R134a under electric field is very scarce. In this work, an improved evaporation model accounting for the effects of the corona wind, Coulombic fission and electric force under the electric field was developed and validated to evaluate the importance of the electric field on the moving charged R134a droplet evaporation for the first time. Results demonstrated that the electrostatic field can improve the charged droplet evaporation by means of the heat and mass transfer enhancement by the corona wind and counteracting the drag force from air. The droplet lifetime was shortened by 20.8% (from 105.6 ms to 83.6 ms) when the applied voltage increased from 0 kV to 10 kV. Exponential decay in the charged droplet lifetime when the applied voltage increased was observed. © 2021 ICLASS 2021 - 15th Triennial International Conference on Liquid Atomization and Spray Systems. All Rights Reserved.

关键词： Drops

Research on Artificial Neural Network for Geometric Design and Optimization of Three-Stage Segmented Thermoelectric Generators

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SSRN 2024年

作者： Zhang, Yin Guo, Kailun Wang, Chenglong Zhang, Jing Wang, Yulu Tian, Wenxi Su, Guanghui Qiu, Suizheng School of Nuclear Science and Technology Shanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China School of Mechatronic Engineering Xianyang Vocational Technical College Xi’an712000 China

More green and environmentally friendly electricity production is the driving force for the development of thermoelectric generators. In addition to high-performance thermoelectric materials, optimizing the geometric shape of thermoelectric generators can also maximize thermoelectric efficiency. This work applies artificial neural networks to the design and optimization of a three-stage segmented thermoelectric generator. After verifying the thermoelectric numerical model of COMSOL, this work generated 3000 sets of simulation data for neural network training. After hyperparameter and particle swarm optimization, the trained neural network can exhibit extremely high prediction accuracy. By coupling the genetic algorithm and artificial fish swarm algorithm, the trained artificial neural network can optimize eight geometric parameters of a three-stage segmented thermoelectric generator under different temperature differences. Compared with COMSOL optimization results, the conversion efficiency optimized by GA has increased by 1.42% and 2.48% in cases 1 and 2, respectively;The conversion efficiency optimized by AFSA has increased by 3.61% and 2.86% in cases 1 and 2, respectively. By obtaining almost identical optimization values, the neural network can achieve geometric design optimization within 5 minutes under different temperature differences. This method provides a new and economical avenue for rapid prediction and design of thermoelectric generators. © 2024, The Authors. All rights reserved.

关键词： Genetic algorithms