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A Gpu-Accelerated Multi-Resolution Lsmps Method for multiphase flows Simulation with Gas-Liquid Phase Transition

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SSRN 2024年

作者： Cao, Sheng Ren, Qianyong Wang, Wenpeng Zhang, Bin Shan, Jianqiang School of Nuclear Science 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

The meshless Lagrangian method (particle method) demonstrates significant advantages in simulating multiphase flows with highly dynamic phase interfaces and has been widely applied in research areas such as ocean engineering, nuclear engineering, and aerospace engineering. The least squares moving particle semi-implicit (LSMPS) method theoretically attains high-order accuracy, significantly enhancing the precision and stability of simulations. However, compared to traditional Eulerian methods, its numerical discretization is more complex and computationally intensive, which limits its applicability in large-scale simulations. To mitigate these challenges, a multi-resolution particle model is implemented to reduce computational costs, and algorithmic improvements and optimizations enable GPU-based parallel processing, significantly boosting computational efficiency. Building on this foundation, a high-precision surface particle detection algorithm and a stable gas-liquid phase transition model are developed. The phase transition model integrates the volume change resulting from phase transition as a source term in the pressure Poisson equation. Benchmark tests of single bubble rising in liquid, Rayleigh-Taylor instability, and two-dimensional horizontal film boiling were conducted to validate the accuracy and efficiency of the GPU- accelerated multi-resolution LSMPS method for simulating multiphase flows, thereby promoting the application of the LSMPS method in both scientific research and practical engineering. © 2024, The Authors. All rights reserved.

关键词： Poisson equation

Characteristics and Prediction Model of Co-Pyrolysis of Sewage Sludge and Camellia Seed Shell

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SSRN 2022年

作者： Wang, Bo Liu, Yinhe Guan, Yu Feng, Yiwei Pan, Hejitian State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi’an710049 China

Tar is an undesired product in the process of sewage sludge pyrolysis, which affects the normal operation of the equipment. In this paper, the characteristics of co-pyrolysis of sewage sludge and camellia seed shell for tar reduction and syngas production were explored. The content and composition of tar and pyrolysis gas co-pyrolyzed with different proportions of sewage sludge (JAS) and camellia seed shell samples (CSS) were studied. The weight loss characteristics of the samples were studied by thermogravimetric experiment, and the synergistic effects of different stages were analyzed. The performances of back propagation (BP) neural network and particle swarm optimization-back propagation neural network (PSO-BP) in reflecting the nonlinear relationship between temperature, mixing ratio, heating rate and remaining weight were compared. The results show that the tar yield was the lowest when 40JAS60CSS was pyrolyzed, which could alleviate the serious problems caused by the tar. Compared with the JAS single pyrolysis, the co-pyrolysis of JAS and CSS improved the content of PAHs and reduced the content of aliphatic hydrocarbons in the tar. The inhibition and promotion effects of co-pyrolysis would be transformed into each other with the progress of the pyrolysis, and the transformations were concentrated in the S 2 stage where the weight loss of the sample is the largest. The constructed PSO-BP-30 model contained two hidden layers, each with 12 neurons, which accurately reflected the nonlinear relationship between the temperature, mixing ratio, heating rate and residual weight. © 2022, The Authors. All rights reserved.

关键词： Pyrolysis

Enhancing thin film boiling heat transfer through electric field and surface Macro-Structure Synergy: Insights from bubble dynamics modulation

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International Journal of Heat and Mass Transfer 2025年 249卷

作者： He, Changqiu Tian, Jiameng Chen, Yiqi Zhu, Yuchen Liu, Xin Wang, Hai Wang, Zhentao Cai, Benan Wang, Changqing Wang, Junfeng Zhou, Zhifu Chen, Bin School of Energy and Power Engineering Jiangsu University Zhenjiang212013 China School of Energy and Power Engineering Chongqing University Chongqing 400044 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Laboratory of Thermo-fluid Science and Nuclear Engineering School of Energy and Power Engineering Northeast Electric Power University Jilin 132012 China National Key Laboratory of Marine Engine Science and Technology Shanghai 201108 China

Improving boiling heat transfer in thin liquid films by employing external electrical fields and macro-structured surfaces presents promising for tackling the growing difficulties related to high-heat-flux thermal management in electronic devices. In this study, six distinct macro-structured surfaces are designed and fabricated to gain insight into how liquid film thickness, structural parameters, and applied voltage affect the efficiency of boiling heat transfer with ethanol as the coolant. High-speed imaging and precise heat transfer measurements are employed to characterize the boiling performance, providing insights into the underlying fundamentals driving the observed enhancements. Results reveal that applying a 4-kV voltage increases departure frequency of bubble by 86 % and a 28 % reduction in diameter, causing a 20 % improvement in critical heat flux (CHF). CHF is positively correlated with liquid film thickness and pin height, but negatively with pin spacing, achieving a 139 % increase under optimal conditions. Liquid film thickness was found to have the most significant impact on CHF, followed by pin spacing and applied voltage. By simplifying the void fraction equation, a new CHF correlation is proposed that introduces a dimensionless characteristic length, representing the relative effects between bubble size and film thickness, while accounting for the synergy between the electric field and surface macro-structure. © 2025 Elsevier Ltd

关键词： Electric heating

Thermal Characteristics and Structural Parameters Optimization of Apg/Cu/Pcm Integrated Architecture

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SSRN 2024年

作者： Su, Lizheng Zhang, Tianning Li, Xiaoyang Li, Dong Jiang, Xinyu Xie, Zhongnan Xi'an Electronic Engineering Research Institute Xi’an710100 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China State Key Laboratory of Nonferrous Metals and Processes GRINM Group Co. Ltd. Beijing100088 China

The challenges faced by radar seeker primarily stem from inadequate heat dissipation in chips and excessive weight. To address these issues, this study introduces a novel integrated phase-change heat sink architecture, composed of a copper alloy matrix, annealed pyrolytic graphite (APG), and phase-change materials (PCMs) serving as heat conduction reinforcements. The numerical analysis of the heat dissipation performance of this architecture is conducted using Fluent software. The study evaluates the impact of APG anisotropy, APG/Cu interface thermal resistance, APG thickness, and surface area on the heat conduction efficiency. Results demonstrate that APG facilitates a uniform in-plane temperature distribution, allowing PCMs to absorb heat more evenly. Consequently, APG proves effective in enhancing heat dissipation and safeguarding chips from high temperatures. In comparison to a pure copper component, the APG/Cu/PCM structure reduces chip temperature by a substantial 56.27%. Furthermore, increasing the surface area of APG generally contributes to an enhanced heat transfer capability of entire architecture. The paper presents a quantitative relationship between APG surface area and optimal thickness. Importantly, APG satisfies the lightweight requirement, further emphasizing its suitability for addressing the thermal challenges in radar seeker structures. © 2024, The Authors. All rights reserved.

关键词： Phase change materials

Development of a Two-Phase flow Solver with Drift-Flux Model Based on Openfoam: Validation Against Single/Two-Phase and Boiling flow

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SSRN 2024年

作者： Wu, Wenqiang Zhang, Dalin Huang, Tao Du, Peng Zhou, Lei Wang, Bo Deng, Jian Qiu, Zhifang Tian, Wenxi Qiu, Suizheng Su, Guanghui State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China Nuclear Power Institute of China 328 Changshun Avenue Chengdu610213 China

Based on the open-source platform OpenFOAM, this paper implements a two-phase flow solver for drift flux models with realistic closure relations. The solver inherits the numerical method from the OpenFOAM framework, adopts the PIMPLE algorithm, and follows its discrete and matrix-solving criteria, focusing on developing a two-phase flow model and constitutive models. The drift velocity model is based on Ishii and his collaborators’ work. The remaining models, such as wall friction, wall heat transfer, interfacial heat and mass transfer, are taken from TRACE Theory Manual. To fulfill the condition of conjugate heat transfer between fluid and solid, a virtual solid heat transfer function is developed under the premise of a single-domain solver. Extensive and successful validation has been conducted involving single-phase, two-phase, and boiling flow heat transfer phenomena by comparing with experimental data or typical system codes, and the two-phase flow solver's success has been demonstrated in several aspects. © 2024, The Authors. All rights reserved.

关键词： Two phase flow

The Proposal and Calculation Method of the Annular Domain Weight Function for the Electromagnetic flowmeter Under Annular Conductivity Distribution

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SSRN 2024年

作者： Yang, Yang Yang, Biaohu Zhang, Chao Yang, Bin School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Shanghai200093 China

The electromagnetic flowmeter has many advantages, including non-invasiveness, absence of movable parts, high reliability, and insensitivity to physical properties of fluid such as density, temperature, pressure, and viscosity. However, it is susceptible to the impact of non-uniform distribution of medium conductivity. Therefore, studying the characteristic of weight function distribution under non-uniform conductivity distribution is of significant importance for expanding the engineering applications of electromagnetic flowmeter. This includes the case where the conductivity distribution is annular. In this paper, the influence of annular feature input parameters on the weight function distribution is explored by changing the radial distribution size and conductivity ratio of the center and outer ring under annular conductivity distribution. The research results indicate that annular feature input parameters will have complex effects on the distribution of weight function for electromagnetic flowmeter. However, an important finding is that the average value of the weight function within any small annular domain of the center or outer ring remains constant as the radial position changes. Therefore, this paper innovatively proposes the concept of ‘annular domain weight function’. It utilizes the average weight function of the center and outer ring to represent the contribution of the induced electromotive force generated by the average flow velocity within the center and outer ring under axisymmetric flow distribution to the potential difference between the two electrodes. Furthermore, the relationship between the ratio of the annular domain weight function of the center and outer ring and the annular feature input parameters is further studied. Ultimately, the expressions for calculating the weight function of the center and outer ring are obtained. This will be crucially significant for establishing theoretical response model for electromagnetic flowmeter under an

关键词： Distribution functions

Theoretical Study on Predicting the Performance of Steam Ejector by Analogy Method

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Theoretical Study on Predicting the Performance of Steam Eje...

IEEE Asia power and Energy engineering Conference (APEEC)

作者： Yiguo Mei Keneng Qian Yuyan Hou Weixiong Chen Huaxin Consulting Design and Research Institute Co. Hangzhou China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

At present, it is difficult to obtain steam with high pressure under conventional laboratory conditions, and there are certain operational risks in the production of high-pressure and high-temperature steam devices. In this paper, a method to predict the critical entrainment ratio of the steam ejector by using the critical entrainment ratio of the air ejector is proposed. According to the one-dimensional calculation model of the ejector, the parameters related to the critical entrainment ratio are derived. The mathematical relationship between the entrainment ratio and each parameter is found through the mathematical tool Matlab. The performance of the ejector with different working mediums is simulated and verified by Fluent. The research results in this paper show that the entrainment ratio of air and steam ejector is linear with the pressure ratio within a certain range of pressure ratio. Under this linear relationship, the experimental entrainment ratio of the air ejector can be used to predict the entrainment ratio of the steam ejector. In a certain linear range, the relative error between the entrainment ratio predicted by the method proposed in this paper and the simulation results is within 10%.

关键词： Electrical engineering Simulation Fitting Production Media Numerical simulation Market research

Heat Transfer Prediction of Supercritical Carbon Dioxide in Vertical Tube Based on Artificial Neural Networks

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Journal of Thermal Science 2021年第5期30卷 1751-1767页

作者： ZHU Bingguo ZHU Xinjie XIE Jian XU Jinliang LIU Huan Key Laboratory of Power Station Energy Transfer Conversion and System North China Electric Power UniversityMinistry of EducationBeijing102206China School of Mechanical&Electronical Engineering Lanzhou University of TechnologyLanzhou730050China Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization North China Electric Power UniversityBeijing102206China

Accurate prediction of supercritical CO_(2)(scCO_(2))heat transfer is important for heat exchanger design and safe operation of scCO_(2)power *** main prediction method is empirical *** paper demonstrates an alternative way by artificial neural networks(ANN)model with two hidden *** assess widely cited correlations and newly developed ANN model,scCO_(2)heat transfer experiment in vertical tube with pressure up to 20.8 MPa was performed to extend experiment database,which includes 2674 *** with empirical correlations,the ANN model is promising for following advantages:(1)ANN model has much better prediction *** mean relative error,mean absolute relative error and the root-mean-square relative error between predicted and measured wall temperatures are eA=0.38%,eR=4.88%and eS=7.29%,respectively.(2)ANN model performs faster computation speed.(3)ANN model can accurately and speedily predict scCO_(2)heat transfer performance for both normal heat transfer and heat transfer deterioration *** trained ANN program is provided with this paper,which is a useful tool and can be directly applied in engineering of scCO_(2)heat transfer.

关键词： supercritical CO_(2) heat transfer prediction ANN model correlations

An Experimental Study on Ash Deposition Problem of Low-Low Temperature Flue Gas System 9th

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An Experimental Study on Ash Deposition Problem of Low-Low T...

9th International Symposium on Coal Combustion, ISCC 2019

作者： Yan, Yu Jiang, Jiahao Guo, Jin Li, Yuesheng Deng, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Guangdong Institue of Special Equipment Inspection and Research Foshan528251 China Guangdong Institue of Special Equipment Inspection and Research Shunde Institue of Inspection Foshan528300 China

ISBN: (纸本)9789811616563

In order to achieve the ultra-clean emission standards, many power plants in China have completed the installation of low-low temperature flue gas system. However, during the operation of this system, many problems have emerged, such as the ash deposition problem in the heat exchanger and dry ESP (electrostatic precipitator). In this paper, the fixed adsorption system and entrained flow experimental system were built to study the ash deposition characteristics in low-low temperature flue gas system under different temperatures and particle sizes. The repose angle was measured to evaluate the flowability and adhesion capacity of ash particles. The results show that as the increase of adsorption time, the particle size increased gradually, and the agglomeration effect is attenuated after the particles have reached adsorption saturation. The time at which the ash particles began to agglomerate with each other was defined as the agglomeration threshold. As the adsorption temperature decreased, the particle size growth rate increased. The smaller the size of ash particles, the more significant the agglomeration effect. Large particles were easy to adsorb small particles, but the agglomeration effect between large particles was weak. In addition, in the initial stage of particle agglomeration, it was mainly included the adhesion between smaller particles and the adhesion of smaller particles on the surface of large particles. The followability of the ash particles was greatly reduced after the adsorption and agglomeration process. The repose angle of the ash particles increased as the temperature of the flue gas decreased. The smaller the particle size, the larger the repose angle changes, and the more pronounced the repose angle is influenced by the adsorption temperature. The flue gas temperature cannot be blindly dropped in pursuit of high sulfur oxide removal efficiency and dust removal efficiency. © 2022, Tsinghua University Press.

关键词： Particle size