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Study on startup characteristics of prototype once-through steam generator for China fast reactor

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International Journal of Advanced Nuclear Reactor Design and Technology 2022年第1期4卷 26-35页

作者： Min, Xin Zhang, Dalin Xu, Rongshuan Wang, Shibao Chen, Youchun Wang, Chenglong Tian, Wenxi Qiu, Suizheng Su, G.H. State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China

Once-through steam generator (OTSG) is a vital heat transfer equipment of China Fast Reactor-600 (CFR-600), and its startup characteristics are of great importance to the safe operation of nuclear power plant. In this paper, first of all, the Thermal-hydraulic analysis Code Of Sodium heated once-through Steam generator (TCOSS) has been further optimized, and the code was introduced in the text. Secondly, the Steam Generator Test Facility (SGTF) and India Commercial Fast Breeder Reactor (CFBR) were selected for steady-state verification, and the feedwater flow rate increase condition of the prototype OTSG experiment was selected for transient verification. All the verifications were in good compliance, which proved the reliability of the TCOSS code for subsequent calculation of startup conditions. Finally, taking the prototype OTSG of CFR-600 as the research object, and the transient characteristics of cold startup and hot startup have been predicted and analyzed. The results show that both processes of cold startup and hot startup for prototype OTSG can be realized stably. The simulation results of startup processes showed a good agreement with expectations, which can provide support for the development of CFR-600 steam generator. © 2022 Xi'an Jiaotong University

关键词： Steam generators

Experimental Study on Stable Jet Impact Process Under Simulated Pipeline Rupture 21

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Experimental Study on Stable Jet Impact Process Under Simula...

21st IEEE Student Conference on Research and Development, SCOReD 2023

作者： Tao, Zhang Qincheng, Bi Jinle, Zhao Teng, Wang Jingrong, Chen Fan, Feng Xi'an Jiaotong University State Key Lab Multiphase Flow Power Engn Shaanxi Xi'an China North China Electric Power University School of Energy Power and Mechanical Engineering Bao'ding Hebei China

ISBN: (纸本)9798350318821

In this study, an advanced experimental system was utilized that incorporated heating, jetting, recycling, and cooling capabilities to ensure the successful execution of stable jet impact experiment that simulating a pipeline complete rupture. High-temperature resistant tempered glass was employed in the experimental system to realize the visibility. During the experiment, 8mm pipes/nozzles of varying lengths were employed as the test sections, and jetting phenomena when the import status is single-phase cold water or two-phase mixture at 0-2MPa were obtained by high-resolution photos. Additionally, the shape of the jet cone and the impact force exerted on the target plate were meticulously analyzed after the working fluid under different state parameters jetting into an atmospheric pressure environment through pipes/nozzles. The research also focused on the variation trend in the magnitude of the jet-impact force, as a function of inlet pressure and temperature, target plate distances, and length-to-diameter ratios. The research findings revealed that cold water(below 100°C), sub-cooled water(above 100°C but not reaching saturation temperature), and two-phase steam-water mixture exhibited distinct jet cone shapes during the jetting process, resulting in varying distributions of the jet force. Furthermore, the distance from the spout to the target plate and the length-to-diameter ratio significantly influenced the magnitude of the jet impact force. © 2023 IEEE.

关键词： Pipelines

Molecular dynamics study on bubble nucleation characteristics on rectangular Nano-Grooved surfaces

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Journal of Molecular Liquids 2025年 420卷

作者： Li, Zhibin Lou, Jiacheng Wu, Xiaoyi Li, Xujun Chang, Fucheng Wang, Hengyuan Li, Huixiong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China National Key Lab of Aerospace Power System and Plasma Technology School of Mechanical Engineering Xi'an Jiaotong University Xi'an710049 China

The micro/nanoscale structures on metal surfaces are of significant research interest for boiling heat transfer and exhibit great application potential in the thermal management of high-power electronic devices. This study employs the molecular dynamics simulation method to investigate the boiling heat transfer characteristics of hydrophilic rectangular shallow nano-groove structures, comparing them with the smooth surface. The phase transition heat transfer characteristics of liquid films on the smooth surface, single rectangular groove (SRG) surface, and overlapping rectangular groove (ORG) surface are revealed by analyzing the variations of parameters such as energy contour diagrams, bubble volume, liquid film temperature, and average potential energy. The research results indicate that water molecules are in a solid-like state within shallow grooves, while the nucleation sites of initial bubbles form randomly outside the grooves. During the initial heating and bubble growth, the initial nucleation time and bubble growth rate of ORG are slower than those of SRG, due to the small rectangular groove on ORG that diminishes the energy transfer efficiency. During bubble formation and growth, the average kinetic energy within the liquid film fluctuates at the nucleation moment in the critical nucleation region, and the average potential energy rises from −0.083 eV. These findings provide a theoretical basis for the micro/nanoscale structure design of vapor-liquid phase transition thermal management devices. © 2024 Elsevier B.V.

关键词： Kinetic energy

Experimental Study on High-Energy Fluid Jets from a Pipe: Jet Cone Morphology and Impact Force on Flat Plates

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SSRN 2024年

作者： Bi, Qincheng Zhang, Tao Wang, Teng Zhao, Jinle Feng, Fan Liu, Zhaohui State Key Lab Multiphase Flow Power Engn Xi'an Jiaotong University Shaanxi Xian710049 China Department of Power Engineering North China Electric Power University Baoding071003 China

Owing to potential adverse effects such as fatigue, vibration, scouring, and inherent defects, high-pressure pipelines in chemical processes may fail during operation. After failure, high-energy fluid jets into the surrounding space, causing damage to the surrounding equipment and personnel. In extreme cases, the load generated by the jet exerts a reaction force at the pipeline failure point, which causes the pipeline to produce a strong whip, further endangering surrounding systems. To prevent such fundamental and secondary damages, it is important to study the magnitude of the impact force caused by the jetting process and the extent of the impact of the jet cone on surrounding *** this study, an experimental visualization system was utilized that allowed for a continuous and stable heating-jetting-cooling-recovery process for the working fluid. The distance between the nozzle and the impacted target plate can be adjusted on purpose. In this system, deionized water was heated to various conditions (1–8 MPa;20–344 °C) and different states, such as sub-cooled water, two-phase flow, and superheated steam, and then discharged into an atmospheric-pressure environment through pipes of different diameters (2.4–9.2 mm) and length-to-diameter ratios (20–120). Subsequently, the jet cone expanded freely or impacted plates of various sizes and at different distances. Based on the stability and flexibility of this experimental system, new details regarding the jetting process were obtained. Ultimately, a series of experimental data on the jet impact force were obtained, and the expansion morphology of the fluid in the atmospheric-pressure environment was recorded via a high-speed *** experimental results indicate that the water state parameters and the nozzle/pipe structural dimensions significantly affect the shape of the jet cone as well as the magnitude and variation pattern of the jet impact force. Additionally, the jet impact force varies with the distance f

关键词： Atmospheric pressure

Influence Study of the Anisotropic Scattering and Solar Radiation on the Radiation Working Performance of Liquid Droplet Radiator

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SSRN 2024年

作者： Fei, Yiheng Fu, Jianghan Wang, Chenglong Tian, Wenxi Guanghui, S.U. Qiu, Suizheng Department of Nuclear Science and Technology State Key Lab. of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Xi’an710049 China

The Liquid Droplet Radiator (LDR), a lightweight frameless radiant heat rejection system, is widely regarded as the optimal heat rejection solution for megawatt-scale space nuclear power systems. The LDR dissipates heat to space through its droplet layer, which plays a crucial role in determining its radiative rejection capacity. Radiation beams undergo a series of emission, scattering, and absorption processes within the layer before being emitted into space. Prior studies typically assume isotropic scattering in this process. However, this study introduces a 3D model of the LDR layer based on Mie theory and Monte-Carlo methods to investigate the impact of anisotropic scattering and solar radiation. Our calculations reveal that the working fluid exhibits strong forward anisotropic scattering characteristics. Under the anisotropic assumption, the heat rejection capability of the LDR is 27-33% higher compared to the isotropic assumption. Regarding the temperature distribution within the LDR, under the anisotropic assumption, the layer's temperature is 6 K lower at the XY boundary surface and 3 K higher at the layer median, as opposed to the isotropic assumption. We introduce the concept of the probability of a light beam escape to elucidate the distinct beam transmission mechanisms and temperature distribution. When the distance between the LDR and the sun is in the vicinity of 1 AU, the impact of solar radiation on the LDR's ability to operate is on the order of 1E-5, which is almost negligible. This study provides a theoretical foundation for calculating the heat rejection capacity during the LDR design phase. © 2024, The Authors. All rights reserved.

关键词： Solar radiation

Model Predictive Control for Automatic Operation of Space Nuclear Reactors: Design, Simulation, and Performance Evaluation

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SSRN 2023年

作者： Fu, Jianghan Jin, Zhao Dai, Zhiwen Su, Guanghui Wang, Chenglong Tian, Wenxi Qiu, Suizheng Department of Nuclear Science and Technology State Key Lab. of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Xi’an710049 China

Space nuclear reactors possess the inherent benefits of independence from solar energy and the capability to withstand intricate external circumstances. Consequently, the establishment of a dependable automatic control system assumes utmost significance. In this paper, a high-fidelity nonlinear space thermionic nuclear reactor system model is established. An automatic control system with a model predictive control (MPC) controller is designed based on the system. In the case of a nuclear power step response, the MPC controller achieves an overshoot of 0.07% and a settling time of 0.65s. For an electric power step response, the MPC controller yields an overshoot of 0.28% and a settling time of 36.6s. These control performances are better than those achieved by the PID controller. In power tracking control, the MPC controller demonstrates virtually error-free tracking performance. When external reactivity disturbances are introduced, the MPC controller swiftly compensates for the disturbances at the desired level. © 2023, The Authors. All rights reserved.

关键词： Model predictive control

Experimental Study on Stable Jet Impact Process Under Simulated Pipeline Rupture

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Experimental Study on Stable Jet Impact Process Under Simula...

Student Conference on Research and Development (SCOReD)

作者： Zhang Tao Bi Qincheng Zhao Jinle Wang Teng Chen Jingrong Feng Fan State Key Lab Multiphase Flow Power Engn Xi’an Jiaotong University Xi’an Shaanxi China School of Energy Power and Mechanical Engineering North China Electric Power University Bao’ding Hebei China

ISBN: (数字)9798350318821

ISBN: (纸本)9798350318838

关键词： Resistance Visualization Temperature distribution Fluids Shape Force Pipelines

Preliminary Conceptual Design with Neutronics and Thermal-Hydraulics Assessments of Fustar

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SSRN 2023年

作者： Zhou, Xingguang Zhang, Dalin Li, Xinyu Lv, Xindi Jiang, Dianqiang Tian, Wenxi Qiu, Suizheng State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi'an Jiaotong University Xi'An710049 China

The fluoride-salt-cooled high-temperature advanced reactor (FuSTAR) is an advanced small modular reactor, which aims to the electric supplement and clean heat production to western China. In this study, neutronics and thermal-hydraulics analysis are also carried out, and established the core layout and material ratio under the near-critical condition. The parameters of the designed core are evaluated quantitatively from various aspects. The results show that FuSTAR has sufficient shutdown depth, the equilibrium cycle is 3.24 years, and the discharge burnup depth is 106 GWd/MtU. The analysis of 1/6 core porous media shows that the peak fuel temperature under normal operating condition is 1009.3 K, which is far below the limit of 1573 K. Relevant design and analysis results can provide the reference for the subsequent small modular FHR design and construction. © 2023, The Authors. All rights reserved.

关键词： Computational fluid dynamics

Experimental Investigation on flow and Heat Transfer Characteristics of Helium in Rectangular Narrow Slit Channel

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SSRN 2024年

作者： Li, Changzhong Wang, Chenglong Sun, Yanyu Chen, Ronghua Tian, Wenxi Su, Guanghui Qiu, Suizheng State Key Laboratory of Multiphase Flow in Power Engineering China Department of Nuclear Science and Technology Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China China Nuclear Power Engineering Co. Ltd. Beijing100840 China

Helium is utilized as coolant in high temperature gas cooled reactors. Rectangular narrow slit channels are commonly present in the core. The flow and heat transfer properties of helium significantly affect the core temperature and flow distribution. This paper experimentally investigates the flow and heat transfer properties of high temperature helium in rectangular narrow slit channel. The Reynolds numbers ranged from 468 to 5327, the temperature ratio of wall to bulk from 0.91 to 1.22, the helium outlet temperature up to 944 K, and the maximum heat flux density up to 0.101 MW/m². In the experiment, the total and local convective heat transfer coefficients, along with the friction factors, are measured. Correlation equations for the Nusselt number and friction factor with respect to Reynolds number are derived. The primary findings are as below: the friction factors of helium in rectangular narrow slit channels are significantly larger than those calculated by current empirical correlations. In the turbulent zone, the measured local Nusselt numbers are in excellent accordance with the Gnielinski correlation;however, a significant discrepancy exists in the laminar zone. New flow heat transfer correlation equations are proposed on the bases of experimental data. Upon comparison, the total Nusselt numbers fall in the error of 10%, and almost all local Nusselt numbers and the friction factors fall in the error of 20%. © 2024, The Authors. All rights reserved.

关键词： Helium