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Visualization Experiments and Piston Effect of Heat Transfer on Supercritical Carbon Dioxide in a Mini Vertical Upward flow

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SSRN 2022年

作者： Lyu, Haicai Wang, Han Bi, Qincheng Niu, Fenglei School of Nuclear Science and Engineering North China Electric Power University Beijing102206 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road Xi’an710049 China

The characteristics of supercritical heat transfer and flow patterns visualization were investigated experimentally. System parameters are pressure of 7.4 ~ 8.44 MPa, the mass flux of 600 ~ 1600 kg·m -2 ·s -1 and heat flux up to 319 kW·m -2 . The basic experimental data of heat transfer coefficient and frictional pressure drop were obtained. Local heat transfer coefficient was calculated with respect to the mass flux, heat flux and pressure. The scenario of in-tube supercritical carbon dioxide was presented by a high-resolution camera. Experimental results show that the heat transfer peak happens when the wall temperature is above the pseudo-critical temperature, and in-tube fluid is lower than the pseudo-critical temperature. Exciting phenomenon of critical opalescence is observed under the pressure of 7.4 MPa and a temperature of 31.68 ˚C. Rapid alternation of sky blue and milky white was captured in an extremely short period time, which may be related to Rayleigh scattering due to drastic density fluctuation. Piston effect of strongly uneven aggregation was formed due to the variation of thermal physical property, which can be used to exposit the mechanism of supercritical heat transfer peak near the pseudo-critical temperature. Ration of density and volumetric coefficient of expansion can be represented for the piston effect to produce the modified Jackson’s correlation, which owns the average error of -0.69% and root-mean-square error of 10.35%. © 2022, The Authors. All rights reserved.

关键词： Visualization

Numerical investigation of natural convection characteristics of a heat pipe-cooled passive residual heat removal system for molten salt reactors

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Nuclear Science and Techniques 2020年第7期31卷 25-33页

作者： Cheng-Long Wang Hao Qin Da-Lin Zhang Wen-Xi Tian Guang-Hui Su Sui-Zheng Qiu Department of Nuclear Science and Technology Xi’an Jiaotong UniversityXi’an 710049China Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

The limited availability of studies on the natural convection heat transfer characteristics of fluoride salt has hindered progress in the design of passive residual heat removal systems(PRHRS)for molten salt *** paper presents results from a numerical investigation of natural convection heat transfer characteristics of fluoride salt and heat pipes in the drain tank of a *** results are compared with experimental data,demonstrating the accuracy of the calculation *** distribution of fluoride salt and heat transfer characteristics are obtained and *** radial temperature of liquid fluoride salt in the drain tank shows a uniform distribution,while temperatures increase with increase in axial height from the bottom to the top of the drain *** addition,natural convection intensity increases with increase in height of the heat pipes in the *** between heat pipes has no obvious effect on the natural convection heat transfer *** study will contribute to the design of passive heat removal systems for advanced nuclear reactors.

关键词： passive characteristics pipes

Research on the Solution of the Thermo-Hydro-Mechanical-Chemical Coupling Model Based on the Unified Finite Volume Method Framework

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SSRN 2024年

作者： Zhang, Weitao Han, Dongxu Wang, Bohong Chen, Yu-Jie Jiao, Kaituo Gong, Liang Yu, Bo Qingdao266580 China School of Mechanical Engineering Beijing Key Laboratory of Pipeline Critical Technology and Equipment for Deepwater Oil and Gas Development Beijing Institute of Petrochemical Technology Beijing102617 China National-Local Joint Engineering Laboratory of Harbour Oil and Gas Storage and Transportation Technology Zhejiang Key Laboratory of Petrochemical Environmental Pollution Control Zhejiang Ocean University No.1 Haida South Road Zhoushan316022 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Most existing thermo-hydro-chemical-mechanical (THMC) coupling models for enhanced geothermal systems (EGS) employ a combination of finite volume method (FVM) and extended finite element method (XFEM), facing challenges in framework integration, programming complexity, and solution efficiency. To overcome these limitations, this study develops an innovative FVM-XFVM model based on the embedded discrete fracture model (EDFM) that significantly enhances the THMC coupling modeling process for fractured reservoirs with simplicity and efficiency. Rigorous comparative verification demonstrates the new model maintains accuracy while improving computational performance. For EGS applications, this model effectively captures spatiotemporal dynamics of coupled THMC processes with multi-component water-rock reactions. The approximately 3°C temperature deviation between multi-component and single-component models after long-term operation demonstrates the necessity of incorporating multi-component reactions into THMC models for accurate forecasts. This work substantially improves the predictability and efficiency of long-term heat production forecasts for EGS reservoirs. © 2024, The Authors. All rights reserved.

关键词： Finite volume method

Thermal Modulation of Radiation Fields Enhancing the Adaptability of Cpv-Hydrogen Systems to Hot Outdoor Conditions

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SSRN 2023年

作者： Zhu, Yizhou Zhang, Ting’an Geng, Jiafeng Jing, Dengwei Xi'an University of Science and Technology China Department of Chemical Engineering School of Water and Environment Chang'an University Shaanxi Xi’an710064 China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

The efficiency of photovoltaic (PV) modules operating outdoors often subject to significant decrease due to high PV surface temperature under hot outdoor conditions despite of the high irradiation in this period. Meanwhile, the commercial electrolytic water splitting unit requires additional heat sources to preheat the electrolyte, which is neither economical nor energy efficient. This study introduces a proton exchange membrane (PEM) water electrolyzer system coupled with concentrated photovoltaic (CPV) and a pipe-based liquid spectral beam splitting filter acting also as an electrolyte preheater. The results of continuous experiments during local summer daytime show that the average PV surface temperature of the proposed system can be reduced by 23.5 K compared to that without spectral beam splitting filter. Moreover, the average efficiencies of photovoltaic, electrolysis and solar-to-hydrogen can be increased by 7.5%, 8.1% and 5.2%, respectively. Both simulation and experimental results confirm that our design can reduce the sensitivity of system efficiency toward weather factors, especially high-intensity summer irradiation. This work provides a promising option for application of large-scale solar hydrogen production in regions with sufficient sunlight while high outdoor temperature. © 2023, The Authors. All rights reserved.

关键词： Hydrogen production

flow Fluctuations and flow Friction Characteristics of Lead-Bismuth Eutectic in a Vertical Tube Under Rolling Conditions

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SSRN 2022年

作者： Liu, Zhipeng Zhao, Yafeng Tian, Wenxi Wang, Chenglong Qiu, Suizheng Su, Guanghui H. School of Nuclear Science and Technology Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering China

The effects of rolling motion on the flow characteristics of lead-bismuth eutectic in a vertical circular tube are investigated experimentally. The results show that the pressure drop and flow rate of the forced LBE circulation fluctuate under rolling conditions. The effect of rolling motion on the flow characteristics decreases with the increase of the corresponding static Reynolds number. The rolling motion may increase the time-averaged frictional resistance coefficient of the LBE when flow rate is low. The critical value of the impact Reynolds number is about 125,000. As a result, the time-averaged flow rate decreases. The analysis shows that it is mainly the transverse additional force caused by the rolling motion increases the frictional resistance of the LBE. An empirical correlation is established to predict the frictional resistance coefficient under rolling conditions. This study may be useful in the thermal-hydraulic analysis of LBE as a working fluid under moving conditions. © 2022, The Authors. All rights reserved.

关键词： Reynolds number

Hydrodynamic and heat transfer properties of magnetic fluid in porous medium considering nanoparticle shapes and magnetic field-dependent viscosity

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Chinese Journal of Chemical engineering 2020年第2期28卷 329-339页

作者： Mohsen Izadi Masoud Javanahram Seyed Mohsen Hashem Zadeh Dengwei Jing Mechanical Engineering Department Lorestan UniversityKhorramabadIran Mechanical Engineering Department Islamic Azad UniversityBushehrIran Department of Mechanical Engineering Shahid Chamran University of AhvazIran School of Energy and Power Engineering State Key Lab of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

The purpose of this paper is to study the characteristics of the combined convection heat transfer and a micropolar nanofluid flow passing through an impermeable stretching sheet in a porous *** nanofluid flow field is affected by a magnetic field perpendicular to the *** dynamic viscosity of the micropolar nanofluid changes under the influence of the magnetic *** continuity,linear momentum,angular momentum,and energy equations are first simplified using the order of magnitude technique that,along with the applied boundary conditions and the definition of the appropriate parameters,are transferred to the similarity space using the similarity *** the resulting equations are solved using the Runge–Kutta *** distinction of the macroscale and microscale flow fields and temperature fields resulting from different nanoparticle shapes was *** the Hartmann number,the vortex viscosity parameter,the magnetic parameter,the nanoparticle volume fraction,and the permeability parameter of the porous media increased the surface friction on the *** the vortex viscosity parameter,the magnetic parameter,and the volume fraction of the nanoparticles increases the Nusselt number.

关键词： MHD-combined convection Porous media Magnetic micropolar nanofluid

Light doping of tungsten into copper-platinum nanoalloys for boosting their electrocatalytic performance in methanol oxidation

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Nano Research Energy 2022年第2期1卷 194-200页

作者： Danye Liu Qing Zeng Chaoquan Hu Dong Chen Hui Liu Yongsheng Han Lin Xu Qingbo Zhang Jun Yang State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Nanjing IPE Institute of Green Manufacturing Industry Nanjing 211100China School of Chemistry and Materials Science Jiangsu Key Laboratory of New Power BatteriesJiangsu Collaborative Innovation Centre of Biomedical Functional MaterialsNanjing Normal UniversityNanjing 210023China Department of Bioengineering Rice UniversityHoustonTexas 77005USA

Coupling the bi-functional mechanism with compressive lattice strain might be an effective way to boost the electrocatalysis of platinum(Pt)-based nanoparticles for methanol oxidation reaction(MOR).This strategy weakens the chemisorption of poisoning CO-like intermediates generated during MOR on the active Pt sites by lowering their d-band *** this context,we herein report the synthesis of ternary copper-tungsten-platinum(CuWPt)nanoalloys with light doping of W element by simply co-reducing their precursors at elevated *** this ternary alloy system,the presence of only small amount of W element not only weakens the chemisorption of CO-like intermediates by lowering the Pt d-band center through compressive lattice strain,but also cleans the active Pt sites by“hydrogen spillover effect”,endowing the as-prepared CuWPt nanoalloys at an appropriate Cu/W/Pt ratio with good activity for *** specific,the ternary CuWPt alloy nanoparticles at a Cu/W/Pt molar ratio of 21/4/75 show a specific activity of 2.5 mA·cm^(−2)and a mass activity of 2.11 A·mg^(−1)with a better durability,outperforming those ternary CuWPt alloy nanoparticles at other Cu/W/Pt ratios,binary CuPt alloys and commercial Pt/C catalyst as well as a large number of reported Pt-based *** addition,a single direct methanol fuel cell(DMFC)assembled using ternary CuWPt nanoalloys as anodic catalysts shows a power density of 24.3 mW·cm^(−2)and an open-circle voltage of 0.6 V,also much higher than those of the single DMFC assembled from commercial Pt/C catalysts.

关键词： lattice strain d-band center electrocatalysis hydrogen spillover methanol oxidation reaction

Development of Pwr Lower Head Failure Model for Severe Accident Analysis

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SSRN 2022年

作者： Gao, Pengcheng Yang, Hao 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

Under the in-vessel retention (IVR) scenario, the lower head is loaded by the deadweight of melt and the vessel, the internal pressure, and the temperature field. This thermo-mechanical load will destroy the integrity of the reactor pressure vessel (RPV). The failure of the lower head indicates that the in-vessel accident progression has entered the final stage. If the failure occurs, its location and time have to be evaluated. However, most severe accident analysis codes judge RPV failures based on simple parametric models, which cannot accurately predict the failure time, modes, and locations. In this paper, the LHTMB (Lower Head Thermal-Mechanical Behavior) analysis module is developed to analyze the thermal-mechanical behavior of lower head by referring to the generalized Hooke’s Law, and combined with various failure criteria to judge RPV rupture. The module consists of three parts: thermal-mechanical behavior, failure judgment, and format output. The LHTMB module was verified by the OLHF-1 experiment data and numerical simulation results. The mechanical results show that creep rate is usually highest at the location where the lower head is most prone to failure. Comparison of various failure criteria shows that RPV failure can be determined with high confidence when Larson-Miller life fraction and Hedl-Dorn parameter criteria are satisfied. © 2022, The Authors. All rights reserved.

关键词： Failure (mechanical)

Experimental study on mercury content in flue gas of coal-fired units based on laser-induced breakdown spectroscopy

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Plasma Science and Technology 2020年第7期22卷 75-82页

作者： Kai RONG Zhenzhen WANG Ruomu HU Renwei LIU Yoshihiro DEGUCH Junjie YAN Jiping LIU State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049People’s Republic of China Graduate School of Technology Industrial and Social SciencesTokushima UniversityTokushima 770-8501Japan Moe Key Laboratory of Thermo-Fluid Science and Engineering Xi'an Jiaotong UniversityXi'an 710049People’s Republic of China

Accurate measurement of trace heavy metal mercury(Hg) in flue gas of coal-fired units is great significance for ecological and environmental *** gas was used to simulate the actual flue gas of a power plant in this study.A laser-induced breakdown spectroscopy(LIBS)system for Hg measurement in mixed gas was built to study the effect of mixed gas pressure,Hg concentration in mixed gas and delay time on Hg *** experimental results show that the appropriate low mixed gas pressure can obtain high Hg signal intensity and signal to noise *** Hg signal intensity and signal to noise ratio increased with the increase of Hg concentration in mixed *** Hg signal intensity and signal to noise ratio decreased with the increase in delay *** to the above results,the optimized measurement conditions can be *** Hg concentrations in mixed gas were quantitatively analyzed by the internal standard method and traditional calibration method *** relative error of prediction of the test sample obtained by the internal standard method was within 11.11%.The relative error of prediction of the traditional calibration method was less than 14.54%.This proved that the internal standard method can improve the accuracy of quantitative analysis of Hg concentration in flue gas using LIBS.

关键词： laser-induced breakdown spectroscopy flue gas trace heavy metal quantitative analysis