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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

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Study of flow Pattern Transition Criterion and Heat Transfer Characteristics in Vertical Rectangular Narrow Channel for Steam Heating

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SSRN 2023年

作者： Gu, Shengjie Tao, Leren Jin, Cheng Ju, Yiwei Zhao, Xiefei 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 and Engineering University of Shanghai for Science and Technology Shanghai200093 China

To clarify the heat transfer characteristics of flow boiling in a narrow vertical rectangular channel at each stage and optimise the performance of the heat exchanger, an experimental study of the flow pattern and local heat transfer characteristics in a narrow vertical rectangular channel of steam heating with dimensions of 1400 mm × 250 mm × 2.75 mm (l × w × s) was carried out using deionized water as the working medium. Based on the mechanical model and the empirical formulas of the researchers, the preliminary derivation of the flow pattern transition criterion in the vertical rectangular narrow channel for steam heating is obtained. The effects of inlet temperature, mass flux and heating power on the local heat transfer characteristics were analyzed in conjunction with the flow patterns, and based on the parametric analysis of the experimental data, a new flow boiling heat transfer correlation formula was obtained which applies to the experimental conditions in this paper. The results show that the increase in inlet temperature has a positive effect on the nucleate boiling section, while the degree of effect on the local heat transfer coefficient is minimal after entering the churn flow phases. The increase in mass flux decreases the local heat transfer coefficient in the nuclear state boiling stage and enhances the local heat transfer coefficient in the evaporation zone of liquid film flow. The peak of the local heat transfer coefficient shows a tendency to shift to the left as the heating power increases. The new heat transfer correlation equation can well predict the local heat transfer coefficient of flow boiling in a vertical rectangular narrow channel heated by steam in this experimental condition. © 2023, The Authors. All rights reserved.

关键词： flow patterns

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Experimental study on the contribution of included/excluded minerals to particulate formation during coal char combustion

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Fuel 2023年第1期346卷

作者： Shang, Yimin Liu, Siqi Niu, Yanqing Zhu, Guangqing Cheng, Zening Hui, Shi'en State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Shaanxi710049 China China Nuclear Power Technology Research Institute Shenzhen518031 China Zhundong Energy Research Institute Xinjiang Tianchi Energy Co. Ltd. Xinjiang831100 China

The contributions of included and excluded minerals to particulate matter formation are quantified in this work. By devolatilization of three typical Chinese coals, three coal chars with low (LA), moderate (MA), and high ash (HA) content (with both included and excluded minerals) were prepared, from which three float coal chars with low (LA−), moderate (MA−), and high ash (HA−) content (without excluded minerals) were separated by density differentiation method. The coal chars before and after separation were burned in a drop-tube furnace at 1600 K, the results of three float coal chars can directly reveal the contribution of included minerals, and the comparison of two kinds of chars with and without excluded minerals would reveal the excluded mineral contribution to ash distribution. The size distributions of the combustion-generated ash particle were obtained from the combination of ELPI+ and laser particle-size analyzer. The fractions of included/excluded minerals were obtained from SEM images. The results from the combustion of the float chars indicate the physical transformation of included minerals, while the results from original coal chars involve the transformation of both included and excluded minerals. Results indicate that the distribution of ash particles from included minerals for HA− char possesses a single peak, while the ash distributions of MA− and LA− char show a bi-modal shape. The excluded minerals in LA and MA chars mainly contribute to the ash emissions with sizes larger than 80 μm. The contribution from excluded minerals reach 86% to the ash particles of 205 μm for HA char, 54% for MA char and 51% for LA char. The number fractions of included minerals continuously decrease with a transformation into excluded minerals during char dynamic combustion. © 2023 Elsevier Ltd

关键词： Minerals

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Influence of Different Equations of state on Simulation Results of Supercritical CO_(2) Centrifugal Compressor

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Mechanical engineering Science 2021年第2期3卷 25-33页

作者： Yueming YANG Bingkun MA Yongqing XIAO Jianhui QI Shandong Engineering Laboratory for High-efficiency Energy Conservation and Energy Storage Technology&Equipment School of Energy and Power EngineeringShandong UniversityJinanChina Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization North China Electric Power UniversityBeijingChina

Supercritical CO_(2)(SCO_(2))Brayton cycle has received more and more attention in the field of power generation due to its high cycle efficiency and compact ***_(2) compressor is the core component of the cycle,and the improvement of its performance is the key to improving the efficiency of the entire ***,the operation of the SCO_(2) compressor near the critical point has brought many design and operation *** on the Reynolds Averaged Navier-Stokes(RANS)model,the performance and flow field of SCO_(2) centrifugal compressors based on different CO_(2) working fluid models are numerically investigated in this *** stability and convergence of the compressor steady-state simulation are also *** results show that the fluid based on the Span-Wanger(SW)equation can obtain a more ideal compressor performance curve and capture a more accurate flow field structure,while the CO_(2) ideal gas is not suitable for the calculation of SCO_(2) centrifugal *** its flow field can be used as the initial flow field for numerical calculation of centrifugal compressor based on CO_(2) real gas.

关键词： Supercritical CO_(2) Centrifugal compressor Near the critical point Compressor performance Real gas equation of state

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Stress analysis of heat exchange tube with inner and outer fins under convection heat transfer conditions

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Huagong Xuebao/CIESC Journal 2011年第SUPPL. 1期62卷 86-91页

作者： Ji, Yanpeng Ma, Ting Zeng, Min Wang, Qiuwang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi China

The heat exchange tube with inner and outer fins has been widely applied in industry in order to enhance the performance of heat exchangers. When it is used in high temperature environment, the security must be considered. A three-dimension model was established to simulate the thermal stress by software ANSYS. The results indicated that the main factor, which had effect on the stress and deformation, was temperature and the maximum stress occurred at the joint location between inner fins and tubes. The inner pressure distribution of tube could enhance the effect of stress. On the contrary, the outer could weaken the effect. © All Rights Reserved.

关键词： Finite element method

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Enhanced Clathrate Hydrate Phase Change with Open-Cell Copper Foam for Efficient Methane Storage

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SSRN 2022年

作者： Yang, Liang Li, Chunxiao Pei, Junhua Wang, Xin Liu, Ni Xie, Yingming Cui, Guomin Liu, Daoping 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

Rapid phase change of hydrate with high gas storage capacity is very important for the application of natural gas hydrates technology. Three pieces of open-cell copper foam (CF) with different pore densities (or pores per inch, PPI) herein were immersed in sodium dodecyl sulfate (SDS) solution for enhancing methane storage in solid hydrate. The promotion effects of CF on the methane hydrate formation in the metal-embedded systems were investigated via an unstirred tank reactor. The results demonstrated that the surface of CF skeleton is covered with abundant micro holes and micro grooves, which can provide many metal nuclei for gas–water crystallization. The nest-like metal skeleton acts as crisscross "highway" for the crystallization heat transfer. Methane hydrate was quickly formed in the SDS/CF systems, but CF with the pore densities of 5 and 30 PPI was not favorable for conversion of more water to hydrate. Compared with these two composite systems, the SDS solution with the 15 PPI CF were able to store more methane at a faster formation rate. A theoretical model based highly porous two-phase systems was used to predict the effective thermal conductivity (ETC) of the metal foam filled with hydrate. It was found that the ETC of the hydrate/CF composite was significantly enhanced by employing CF matrix, and the low pore density CF had a more positive impact on improving the ETC of the composite. Further comparative experiments conducted at various pressures indicated that the solutions with 15 PPI CF exhibited higher methane storage capacities and larger hydration rates than the simple SDS solution, especially at the low pressure. © 2022, The Authors. All rights reserved.

关键词： Methane

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Numerical Investigation of Vibrational and Misalignment Effects on Atomization Characteristics of Impinging Jets

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SSRN 2023年

作者： Dai, Qingwen Yang, Jianwen Yang, Bin Wang, Ying School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China Xi’an Aerospace Propulsion Institute Xi’an710100 China

To explore the influence of vibration, misalignment and their combined effects on the atomization characteristics of the impingement process, this paper utilizes the polyhedral mesh adaptive refinement algorithm and VOF-to-DPM multiphase flow model to simulate the atomization process of impinging jets atomization. Additionally, compared the results with experimental data to ensure accurate calculations. The whole process of liquid film broke into liquid filaments and further atomized into droplets under different working conditions are analyzed in this paper. The results show that the proposed algorithm and model can better simulate the two impinging liquid jets atomization. Vibrations cause fluctuations in mass flow, which will lead to the offset of the impingement point by the impinging jets atomization. With the increase of vibration frequency, the performance of atomization become worse. When the vibration frequency is 1000 Hz, the back splash phenomenon becomes more apparent. When the misaligned degree is small, low-amplitude, high frequency vibrations can weaken the influence of misaligned impingement, resulting in improved atomization performance. However, when the degree of misalignment is large, a larger deflection angle of the liquid film results in a smaller broken length of the liquid film and a worse atomization quality. At this time, the vibrations lead to vortices in the atomization field and have an entrainment effect on the atomization field. Therefore, the vibrations have adverse effects on engine thermal protection. © 2023, The Authors. All rights reserved.

关键词： Atomization

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Application of high resolution finite difference scheme in direct numerical simulation of turbulent flow

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2007年第5期28卷 859-861页

作者： Ma, Liang-Dong Li, Zeng-Yao Tao, Wen-Quan State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 China

A direct numerical simulation of a fully developed turbulent flow and heat transfer in a square duct is studied based on high resolution finite difference scheme. The flow and temperature fields are obtained at a turbulent Reynolds number of 400 based on the mean friction velocity and the hydraulic diameter, and the Prandtl number (Pr) of 0.71. Two kinds of point-stencil method are used for the spatial derivatives of the pressure Poisson equation, i.e. the second-order and fourth-order central difference, respectively. The results show that satisfactory solutions can be obtained in the present DNS simulation with coarse grids compared with the method of second-order central difference. And the solutions from the two kinds of point-stencil method for pressure Poisson equation are consistent with the second-order central difference being more economical in saving computation time.

关键词： Pipe flow

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半稳定单原子催化剂增强光热协同催化

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Science Bulletin 2024年第12期69卷 1833-1838页

作者：付亦葳吕科见王怡司亦涛师进文李乃旭周致富刘茂昌 International Research Center for Renewable Energy State Key Laboratory of Multiphase FlowXi’an Jiaotong UniversityXi’an 710049China School of Chemistry and Chemical Engineering Southeast UniversityNanjing 211189China Suzhou Academy of Xi’an Jiaotong University Suzhou 215123China

Single-atom catalysts(SACs)have been extensively studied in photocatalysis,electrochemistry,and ***,their utilization in photothermal catalysis is still in the infancy and is worth investigating,as these catalysts are... 详细信息

关键词： field. catalysis. 单原子催化剂

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Research on surface damage of solid material subjected to high speed liquid impact

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Binggong Xuebao/Acta Armamentarii 2009年第SUPPL. 2期30卷 139-144页

作者： Xie, Yong-Hui Wang, Yong Chen, Jian-Hui Zhang, Di State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an 710049 China

In order to study the surface damage of solid material subjected to the high speed liquid impact, both numerical and experimental methods were established. The smoothed particle hydrodynamics and finite element analysis were used to calculate the material damage. The conditions of PMMA and steel were analyzed to obtain the dynamic stress and strain distribution during impact. An experiment apparatus was build. The velocity of the impact jet was measured using a high speed camera and the apparatus. A digital microscope was used to measure the three dimensional profile of the sample before and after high speed liquid impact up to 600 m/s. The dimensions of damage area were recorded and analyzed statistically. Based on the statistical results, the performance of the materials resisting liquid corrosion was evaluated.

关键词： High speed cameras

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