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SSRN 2022年

作者： Ma, Yugao Wang, Xueqing Yu, Hongxing Huang, Shanfang Zhang, Yingnan Huang, Jian Su, Guanghui Deng, Jian Chai, Xiaoming Hu, Wenzhen School of Nuclear Science and Technology Xi’an Jiaotong University Shanxi Xi’an710049 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Department of Engineering Physics Tsinghua University Beijing100084 China State Key Laboratory of Multiphase Flow in Power Engineering China

High-temperature alkali-metal heat pipes are passive heat transfer devices, where the capillary pressure created by the menisci in the wick pumps the condensed fluid back to the evaporator. Thus, the heat pipe heat transfer capacity is limited by the maximum capillary pressure at high heat fluxes. This work presents a two-dimensional heat and mass transfer model that includes the capillary and gravitational forces that are used to predict the capillary limit which is then validated by experimental data. The predicted critical heat flux temperature has an error of less than 20℃ and a relative error of 6%. The predicted transient sequences are consistent with the measurements. The model shows that capillary limit is affected by inclination angle, heat flux, and wick structure. For inclinations, the critical heat flux at the capillary limit is linearly related to the inclination angle with the predicted temperature rising 2 ~10℃/s during the early stage of the capillary limit critical heat flux condition. The evaporator temperature oscillates before the capillary limit with positive inclinations. For heat fluxes, increasing the heat flux by 17% increases the temperature increase rate 10 fold with a longer dryout length. The evaporator exhibits hysteresis after the capillary limit due to partial dryout of evaporator. For wick structures, reducing the mesh screen pitch from 80 μm to 15 μm reduces the critical heat flux to 10% of the CHF at 80 μm. This model can accurately predict the heat pipe temperature variations at the capillary limit and can explain the physical mechanisms for the dryout oscillations and recovery hysteresis at the capillary limit. Thus, the measurements and model provide analytical guidelines for designing heat pipe cooling systems. © 2022, The Authors. All rights reserved.

关键词： Heat flux

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Investigation into the flow and heat transfer characteristics in liquid metal cooled narrow rectangular channel with rough surfaces

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Case Studies in Thermal Engineering 2025年 72卷

作者： Xue Zhang Wenpei Feng Xiaolong Yang Hongxing Yu Jian Deng Sijia Du Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu 610213 China College of Nuclear Technology and Automation Engineering Chengdu University of Technology Chengdu 610059 China

This study investigates the impact of roughness elements on fluid flow and heat transfer characteristics in narrow rectangular channels. The results show that when the fluid flows over roughness elements, it induces vortices near the wall, disturbing the flow and heat transfer boundary layers. This enhances heat transfer while simultaneously increasing flow resistance. Among different roughness types, cylindrical roughness elements demonstrate a more substantial improvement in both heat transfer efficiency and friction factor compared to cubic elements. The Nusselt number is found to be non-monotonic related to the height of the roughness elements, while the friction factor increases with height. Additionally, larger roughness element diameters lead to higher Nusselt numbers and friction factors. Further analysis reveals that under conditions where the spacing and height remain unchanged, an increase in the roughness elements quantity results in a diminished enhancement of heat transfer. The base edge length of the roughness elements has a more significant impact on heat transfer capacity than the additional heated area, while the additional area primarily affects the flow resistance, causing the friction factor to increase with the number of roughness elements.

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Addition of Niobium in Fe-13cr-4.5al-2mo Alloy Used as Atf Cladding: Effect on High Temperature Water Corrosion and In-Situ Electrochemistry

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SSRN 2022年

作者： Liao, Jingjing Wang, Hui Wu, Jun Zhang, Wei Xu, Fei Sun, Hongying An, Xuguang Qiu, Shaoyu Chengdu University China Science and Technology on Reactor Fuel and Materials Laboratory Nuclear Power Institute of China Sichuan Chengdu610213 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Sichuan Chengdu610213 China School of Mechanical Engineering Anyang Institute of Technology Henan Anyang455002 China Interdisciplinary Materials Research Center Institute for Advanced Study Chengdu University Sichuan Chengdu610106 China

Niobium addition in candidate accident tolerant fuel (ATF) cladding FeCrAl alloy has received much attention, but its effect on high temperature water corrosion behavior has not been revealed. Four alloys with different Nb content (0wt%, 0.5wt%, 1.0wt% and 1.5wt%) based on Fe-13Cr-4.5Al-2Mo model alloy were designed, and the corrosion behavior was investigated by in-situ electrochemistry and microscopy. The in-situ electrochemistry analyses were carried out in 360 。C/19.0MPa lithiated and borated water connected with a loop system to monitor the water chemistry. Detailed studies on the oxide film formed after exposure for 85 days were conducted by focused ion bombarding and transmission electron microscopy. FeCrAl alloys have satisfactory corrosion resistance because of small corrosion currents and thin oxide films. Only monolayer multicrystal spinel oxide forms on alloy surface. Slight Nb addition (0.5% and 1.0wt%) benefits the corrosion resistance due to relatively large impedance of oxide and delayed oxidation of Fe2 Nb particles. Porosities with Fe depletion are spotted in oxide and especially severe in 1.5wt%-Nb alloy. Cathodic Tafel kinetics and corrosion mechanisms of FeCrAl are further discussed. © 2022, The Authors. All rights reserved.

关键词： Oxide films

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Pixel-Level Sea Ice Concentration Retrieval from Sentinel-1 SAR Imagery and Ancillary Data via Regional Loss Representations

Pixel-Level Sea Ice Concentration Retrieval from Sentinel-1 ...

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OCEANS

作者： Xinwei Chen Muhammed Patel Linlin Xu Yuhao Chen David A. Clausi K. Andrea Scott Weimin Huang School of Marine Science and Engineering South China University of Technology Department of System Design Engineering Vision and Image Processing Lab University of Waterloo Department of Mechanical & Mechatronics Engineering University of Waterloo Faculty of Engineering and Applied Science Memorial University of Newfoundland St. John's NL Canada

ISBN: (数字)9798350362077

ISBN: (纸本)9798350362084

The automated monitoring and high resolution mapping of Arctic sea ice concentration (SIC) from synthetic aperture radar (SAR) images are crucial for various purposes, such as tactical navigation. However, the available labels for training deep learning-based SIC estimation models are mostly in coarse spatial resolution. This study tackles this key issue by proposing a novel loss calculation algorithm during model training. Consequently, a U-Net-based model can produce fine-grained SIC estimates via direct learning from ice charts in low resolution. The proposed method is evaluated with the recently release AI4Arctic Sea Ice Challenge Dataset with more than 500 Sentinel-1 SAR imager and associated ice charts. Visual interpretation and numerical results demonstrate the outstanding performance of the proposed method in terms of SIC mapping resolution. The effectiveness of incorporating multi-source ancillary data in performance improvement is also validated.

关键词： Training Visualization Sentinel-1 Estimation Radar polarimetry Numerical models Spatial resolution

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Sound propagation characteristic of phononic crystals pipeline with periodic vibration isolation mass

Sound propagation characteristic of phononic crystals pipeli...

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2020 Transactions of the American Nuclear Society, ANS 2020

作者： Zeng, Qingna Wang, Donghui Zang, Fenggang Zhang, Yixiong Jiang, Xiaozhou Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China 328# 1st section Changshun Dadao Avenue Chengdu610213 China

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Research for the heat leakage caused by gaps on barrel insulation structure of reactor pressure vessel

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International Journal of Advanced Nuclear reactor design and technology 2019年 1卷 30-42页

作者： Tian, Qiu Ying, Luo Yang, Qiu Yu-guang, Li Guo-fu, Xie Li-cai, Yang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China ChengduSichuan Province610213 China

Due to the function requirements of the Cavity Injection and Cooling system, the barrel insulation structure of HPR1000 reactor pressure vessel has been greatly improved compared with the previous projects. In the past, the empirical formula method was used to evaluate the thermal properties of the insulation, but the influences of the support structure and the excessive gap on insulation are difficult to evaluate. In this paper, the fitting formula of the equivalent thermal conductivity and the qualitative temperature of the insulation have been obtained firstly through the heat transfer test. Then, ANSYS Fluent was used to simulate the barrel insulation structure with gaps of HPR1000. A circumferential 15° model was established to obtain evaluation method for flow leakage with gaps in hot state, and then a whole model of the barrel insulation structure with gaps was established to obtain heat loss of insulation based on calculation of flow leakage. The sensitivity of gap size and ventilation parameters to heat leakage was further analyzed. Finally, it was indicated that, by minimizing joint gap length, setting of overlaps, controlling cold gap, optimizing structure of insulation support, the effect of heat leakage caused by gaps can be reduced. © 2019 Xi'an Jiaotong University

关键词： Thermal insulation

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Experimental Study on Droplet Behavior and Mechanisms During Reflooding in a Single-Rod Channel

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SSRN 2022年

作者： Chen, Mingjing Liu, Hanzhou Chen, Deqi Zhong, Lei Liu, Haidong Yu, Hongxing Yu, Ruan Feng, Peng Key Laboratory of Low-grade Energy Utilization Technologies and Systems Chongqing University Ministry of Education Chongqing 400044 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China Key Laboratory of Aerospace Thermophysics Ministry of Industry and Information Technology School of Energy Science and Engineering Harbin Institute of Technology Harbin150001 China

Discrete droplets have received extensive attention in reflooding processes under Loss Of Coolant Accident (LOCA) conditions due to their large vapor-liquid interface area, droplet collision, droplet evaporation, and other behaviors that have a significant impact on the heat transfer of Dispersed Flow Film Boiling (DFFB). Unfortunately, the accurate prediction of the characteristics of droplet velocity and distribution under DFFB cannot be achieved at present, due to the lack of sufficient visual data support. For this reason, a visualization experiment of high-temperature surface reflooding in a single-rod channel was carried out. In this paper, the effect of the thermal parameter, such as input heat flux on the transient droplet behavior, which include the droplet size and velocity, has been analaysed in detail. Furthermore, to provide physical support for building droplet distribution models containing more physical mechanisms in the future, several droplet formation and breakup mechanisms, which include the Helmholtz instability, capillary breakage and rewetting area sputter, has been discussed in this paper. © 2022, The Authors. All rights reserved.

关键词： Drop breakup

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Enhanced Toughness and Ductility of T91 Steel after Exposure to Liquid Lbe Saturated by Oxygen at 350-500 °C

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SSRN 2024年

作者： Zhou, Zhikun Tian, Chenwen Dong, Wenbo Du, Juan Liu, Yunpeng Wahab, Magd Abdel Chen, Ziguang Department of Engineering Mechanics School of Aerospace Engineering Huazhong University of Science and Technology Wuhan430074 China Laboratory Soete Faculty of Engineering and Architecture Ghent University Technologiepark Zwijnaarde 46 ZwijnaardeB-9052 Belgium Institute of Intelligent Manufacturing Jianghan University Wuhan430056 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China College of Engineering Yuan Ze University Taiwan Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment 1037 Luoyu Road Wuhan430074 China

The mechanical tensile properties of T91 steel after being oxidized in liquid LBE saturated by oxygen at 350-500 °C for up to 1,000 h are studied. Duplex oxide scales are found on T91 steels after the LBE exposure, and the thickness evolution is revealed. Oxidized T91 steels with surface oxide scale yield enhanced toughness and ductility, which is mainly attributed to the inner oxide layer. We show that the enhancing effect relies on the presence of the oxide scale, not its thickness. The possible enhancing effect of the oxide scale on the toughness of T91 steel by impeding the dislocation from emitting out of the steel surfaces is discussed and qualitatively verified by micro-scale elastoplastic simulations based on a newly proposed discrete dislocation dynamics and peridynamics superposition scheme. © 2024, The Authors. All rights reserved.

关键词： Ductility

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Cover Picture: Materials and Corrosion. 11/2024

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Materials and Corrosion 2024年第11期75卷 1399-1399页

作者： Wei Zhang Mingyang Zhou Huifang Yue Danmin Peng Xi Qiu Jijun Yang Key Laboratory of Radiation Physics and Technology of Ministry of Education Institute of Nuclear Science and Technology Sichuan University Chengdu China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

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Prediction of boiling crisis in a full-size rod bundle with spacer grids 14

Prediction of boiling crisis in a full-size rod bundle with ...

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14th International Nuclear Fuel Cycle Conference, GLOBAL 2019 and Light Water reactor Fuel Performance Conference, TOP FUEL 2019

作者： Li, Quan Li, Yuanming Avramova, M. Huang, Yongzhong Liu, Zhenhai Ma, Chao Qi, Feipeng Zhao, Bo Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Department of Nuclear Engineering North Carolina State University NC27695 United States

In this paper, two-phase CFD approach is used to simulate the boiling crisis in PSBT rod bundle with spacer grids. The 5×5 rod bundle contains 17 spacer grids, which are finely modeled through UG code. Eulerian two-fluid model coupled with the extended wall boiling model is used to simulate the subcooled boiling flow. The used sub-models for nucleation site density and bubble departure diameter both take the effects of high pressure into consideration. The calculated surface averaged void fraction in the central four sub-channels shows good agreement with the experimental data at high void fraction conditions, while higher than the measured data at low void fraction conditions. Based on the two-phase simulations, the void fraction distribution in the plane section on which thermocouples are placed is used as the criteria for CHF prediction. The numerical simulation of boiling two-phase flow and prediction method of CHF provide new approach for the optimization of spacer grid and fuel assembly. Copyright © GLOBAL 2019 - International Nuclear Fuel Cycle Conference and TOP FUEL 2019 - Light Water reactor Fuel Performance *** rights reserved.

关键词： Forecasting

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