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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

Deterministic Synthesis of Pd Nanocrystals Enclosed by High-Index Facets and Their Enhanced Activity toward Formic Acid Oxidation

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Precision Chemistry 2023年第6期1卷 372-381页

作者： Maochang Liu Siyu Zhou Sang-Il Choi Younan Xia The Wallace H.Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory UniversityAtlantaGeorgia 30332United States International Research Center for Renewable Energy State Key Laboratory of Multiphase FlowXi’an Jiaotong UniversityXi’anShanxi 710049P.R.China School of Chemical and Biomolecular Engineering Georgia Institute of TechnologyAtlantaGeorgia 30332United States School of Chemistry and Biochemistry and School of Chemical and Biomolecular Engineering Georgia Institute of TechnologyAtlantaGeorgia 30332United States

Noble-metal nanocrystals enclosed by high-index facets are of growing interest due to their enhanced catalytic performance in a variety of ***,we report the deterministic synthesis of Pd nanocrystals encased by high-index facets by controlling the rate of deposition(V_(deposition))relative to that of surface diffusion(V_(diffusion)).For octahedral seeds with truncated corners,a reduction rate(and thus deposition rate)faster than that of surface diffusion(i.e.,V_(deposition)/V_(diffusion)>1)led to the formation of concave trisoctahedra(TOH)with high-index *** the reduction was slowed down,in contrast,surface diffusion dominated the growth *** the case of V_(deposition)/V_(diffusion)≈1,truncated octahedra with enlarged sizes were *** the reduction rate was between these two extremes,we obtained concave tetrahexahedra(THH)without or with *** growth patterns were also observed for the cuboctahedral *** the Pd octahedra,concave TOH,and concave THH were tested for electrocatalyzing the formic acid oxidation(FAO)reaction,those with high-index facets were advantageous over the conventional Pd octahedra enclosed by{111}*** work not only contributes to the understanding of surface diffusion and its role in nanocrystal growth but also offers a general protocol for the synthesis of nanocrystals enclosed by high-index facets.

关键词： palladium surface diffusion high-index facet unconventional morphology kinetic control

Insight into the key Role of Imine Groups in Polyaniline for Adsorbing Heavy Metal Ions: Experimental and Density Functional Theory Study

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SSRN 2023年

作者： Shi, Bofang Li, Hang Fu, Xiaojie Zhao, Chengcheng Rao, Yongfang Li, Mingtao Komarneni, Sridhar Yang, Honghui Xi’an Key Laboratory of Sustainable Energy Materials Chemistry Department of Applied Chemistry School of Chemistry Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Department of Environmental Science and Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Ecosystem Science and Management Materials Research Institute 204EEL The Pennsylvania State University University ParkPA16802 United States

In polyaniline (PANI) or polyaniline-based adsorbents, the views on nitrogen group that has the highest chemical affinity to heavy metal ions and dominates the adsorption process remain in debate. Herein, we focus on deciphering the main adsorption sites and adsorption mechanism of PANI using both experiments and density functional theory (DFT) calculations. The characterization results of adsorption product demonstrate that the metal ions were adsorbed via coordination bond between nitrogen atom and metal ion. The theoretical calculations by DFT reveal that −N= group is the key adsorption site rather than other groups in PANI, and the key step of PANI adsorption process is a ligand exchange reaction. The H+ ions with a higher affinity to −N= group can inhibit the adsorption of metal ions due to the consumption of adsorption sites and ion exchange reaction. This work provides a molecular-level understanding of adsorption sites, adsorption mechanism, and H+ competition for metal ion adsorption by PANI, which is beneficial for the development of PANI-based adsorbents. © 2023, The Authors. All rights reserved.

关键词： Density functional theory

Thermally induced non-coalescence of compound droplets

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Applied Thermal engineering 2025年 276卷

作者： Jianmei Zhao Xing Li Bofeng Bai State Key Laboratory of Multiphase Flow in Power Engineering School of Chemical Engineering and Technology Xi’an Jiaotong University Xi'an 710049 China

Compound droplets surrounded by a gaseous phase with different temperatures widely exist in industrial applications. Previous research has focused on thermally induced non-coalescence or delayed coalescence between two single-phase droplets or a droplet and a liquid bath. The primary mechanism is the levitated intervening pressure in the lubricating air layer between droplets, which is caused by the thermocapillary convection. In this study, the non-coalescence of two compound droplets in a cold ambient air environment is experimentally investigated. The thermocapillary mechanism manifests three distinct features. First, as the two compound droplets approach each other, the temperature of the contact side of each droplet increases because of reduced heat loss, a phenomenon termed as the contact-side heating effect. This creates a surface temperature gradient, inducing Marangoni stress and subsequent surface convection. Second, owing to the immiscibility of the two phases within each compound droplet, the thermocapillary convection develops independently in each phase, forming independent convection which cannot be observed in single-phase droplets . It was observed that the directions of the thermocapillary convection within the two droplets were correlated and always planar symmetric, which is different from the uncorrelated and opposite convection of two single-phase droplets. Third and most importantly, the thermocapillary convection in the oil phase entrains the air into the lubricating film between droplets, inhibiting their coalescence only when the oil/water interface is adjacent to the contact zone.

关键词： Compound droplet Non-coalescence Thermocapillary convection

Research on the Performance Enhancement of Accident Tolerant Fuel for Eliminating Core Melting Based on Isaa

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SSRN 2022年

作者： Tang, Shaowei 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

Based on the Integrated Severe Accident Analysis (ISAA) code, this paper studies the influence of thermo-physical properties of Accident Tolerant Fuel (ATF) materials on the plant responses to severe accidents. By selecting ATF with IMDP as the core material and SiC as the cladding material and changing different physical parameters, it is found that fuel density and cladding density have the greatest influence on the fuel temperature rise. In addition, to eliminate core melting, the ATF parameters in ISAA are modified step by step to improve the thermodynamic properties of the fuel, and the core is finally made to reach thermal equilibrium. According to the calculation results, the supporting capacity of the cladding, the supporting capacity of the core supporting plate, and the melting point of the fuel are the main factors limiting the core melting, which can be eliminated by appropriately improving these properties. © 2022, The Authors. All rights reserved.

关键词： Thermodynamic properties

Insight into the key Role of Imine Groups in Polyaniline for Adsorbing Heavy Metal Ions: Density Functional Theory and Experimental Study

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SSRN 2023年

作者： Shi, Bofang Li, Hang Fu, Xiaojie Zhao, Chengcheng Wang, Angelina H. Tan, Weilin Rao, Yongfang Li, Mingtao Komarneni, Sridhar Yang, Honghui Xi’an Key Laboratory of Sustainable Energy Materials Chemistry Department of Applied Chemistry School of Chemistry Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Department of Environmental Science and Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Ecosystem Science and Management Materials Research Institute 204EEL The Pennsylvania State University University ParkPA16802 United States

In polyaniline (PANI) or PANI-based adsorbents, views on which nitrogen group has the highest chemical affinity to heavy metal ions and dominates the adsorption process remain in debate. Herein, we focus on deciphering the main adsorption sites and adsorption mechanisms of PANI using both density functional theory (DFT) calculations and experiments. The theoretical DFT calculations reveal that −N= group, rather than other groups within PANI, is the adsorption site. And the key step of PANI adsorption process is a ligand exchange reaction. In addition, H+ ions with a higher affinity to −N= group can inhibit the adsorption of metal ions through the consumption of adsorption sites and ion exchange reaction. X-ray photoelectron spectra (XPS) spectra demonstrate that maintaining a reasonably high pH value (pH > 4) is an effective way to weaken H+ competition. This work provides a molecular-level understanding of adsorption sites, adsorption mechanism, and H+ competition for metal ion adsorption by PANI, which is beneficial for the development of PANI-based adsorbents. © 2023, The Authors. All rights reserved.

关键词： Adsorption

Experimental Study of Pool Boiling Heat Transfer on Hydrophilic and Hydrophobic Surface Coupled Micro-Pin-Finned

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SSRN 2023年

作者： Song, Gege Ma, Xiang Xu, Pengzhuo Zhang, Yonghai Weia, Jinjia School of Chemical Engineering and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China Xi’an Navigation Technology Research Institute Shannxi Xi’an710068 China Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

The pool boiling heat transfer properties of uniform micro-pin-finned surface, hydrophilic and hydrophobic surface were evaluated by employing FC-72 as the working medium. Three hydrophilic and hydrophobic coupled rectangular copper column surfaces (HH4, HH9, and HH16) were invented in order to investigate their boiling heat transfer characteristics further. The effect of several subcoolings (0K, 15K, and 25K) on the critical heat flux was explored by connecting the micro-pin-finned surface (PF) and the smooth surface (SS). A high-speed camera was set up to study the bubbles' behaviors. The results reveal that the hydrophilic and hydrophobic coupled micro-pin-finned copper surface can achieve a higher critical heat flux (CHF) than the rectangular micro-pin-finned surface, but heat transfer performance (HTC) drops slightly (both saturated boiling and subcooling boiling). Visual monitoring demonstrates that the hydrophilic and hydrophobic coupled rectangular micro-pin-finned copper surface may successfully avoid bubble coalescence, especially during subcooled boiling. Furthermore, the hydrophilic and hydrophobic coupled rectangular micro-pin-finned copper column surface described in this paper might serve as an ideal replenishment route to avoid drying and delay the emergence of a boiling crisis. The factors responsible for the impact of the Lattice width coefficient and the Vapor column spacing coefficient on CHF were analyzed. Fluid replenishment and bubble formation behavior were applied to clarify the strengthened heat transfer and triggering mechanism of CHF on the surface of the hydrophilic and hydrophobic coupled rectangular micro-pin-finned copper column surface. © 2023, The Authors. All rights reserved.

关键词： Heat flux

Pool Boiling Heat Transfer Enhancement on the Hybrid Surfaces Coupling Capillary Wick and Minichannels

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SSRN 2022年

作者： Zhang, Yonghai Ma, Xiang Wang, Jinyu Liu, Wanbo Wei, Jinjia School of Chemical Engineering and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Pool boiling heat transfer can fully utilize the latent heat of the vaporization, to meet the heat dissipation needs of high-power electronic components. In this study, several enhanced hybrid surfaces were designed and processed by sintering spherical copper powder on the minichannels in different ways. The coupled effects of various parameters of capillary wick and minichannels were considered to enhance the pool boiling heat transfer performance of these hybrid surfaces using HFE-7100 as the working fluid. The bubble dynamic behaviors were captured and analyzed by the high-speed camera. The results indicate that the ring groove around the minichannels and the capillary wick have a significant impact on the boiling heat transfer of these hybrid surfaces. This is because the capillary wick provide a large number of nucleation sites and large specific surface area, which can greatly reduce the contact thermal resistance between the capillary wick and the minichannels. At ΔTsub = 30 K, the critical heat flux (CHF) of hybrid surfaces coupling capillary wick and minichannels is up to 147.4 W/cm2, and its maximum heat transfer coefficient (HTC) is 2.69 W/(cm2·K). Compared with minichannels without capillary wick covered, the CHF and HTC are increase by 86.8% and 192.0%, respectively. Furthermore, a correlation for predicting CHF on these hybrid surfaces covered capillary-wick is proposed. Dimensionless parameters such as the subcooled Jakob coefficient (Jasub), the outer surface area enhancement ratio (AER), the particle distribution coefficient (PDC) and the ratio of inner to outer surface area of capillary wick (IOR) are defined to estimate the effect of different factors on the CHF. © 2022, The Authors. All rights reserved.

关键词： Heat flux