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Liutex identification on hairpin vortex structures in a channel based on msfle and moving-PIV

Journal of Hydrodynamics 2021年第6期33卷 1119-1128页

作者： Xin-ran Tang Xiang-rui Dong Xiao-shu Cai Wu Zhou School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Key Laboratory of Multiphase Flow and Heat Transfer in Shanghai Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China

The spatiotemporal evolution of hairpin vortex structures in a fully developed turbulent boundary layer is investigated qualitatively and quantitatively by using two image *** this paper,the moving single-frame and long-exposure(MSFLE)image method is used to intuitively track the evolution process of a hairpin vortex,while the moving particle image velocimetry(moving-PIV)method is applied for obtaining a moving velocity field for quantitative *** to the structural characteristics of the hairpin vortex,an inclined light sheet with an appropriate inclination of 53°is arranged to capture the complete hairpin vortex structure at Re_(θ)=97–*** addition,the core size and the rotational strength of a hairpin vortex are further defined and quantified by the Liutex vector *** evolution process of a complete hairpin vortex structure observed by MSFLE shows that the shear along the normal direction leads to an increasing strength of the hairpin vortex,accompanied by a lifting vortex head and a distance decrease between two vortex legs during the dissipation *** combining moving-PIV with the Liutex identification,the spatiotemporal evolution of four typical regions of a hairpin vortex projecting into a 53°cross-section is *** results show that the process from the generation to the dissipation of a single hairpin vortex can be well characterized and recorded by the Liutex based on the core size and rotational intensity,and the evolution process is consistent with the MSFLE *** to the statistics of vortex core size and rotation intensity along time,the evolution of the hairpin vortex necks and legs can be described as a process of enhancement followed by *** the vortex head,its evolution maintains longer attributed to its far-from-wall position,which consists of an absolute enhancement process(stage 1)with an increasing rotation strength and a constant core size,and an absolute dissipation(stage 2)with a dec

关键词： Turbulent boundary layer hairpin vortex moving single-frame and long-exposure moving particle image velocimetry(PIV) Liutex vortex identification method

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Experimental investigation of nano-particle deposited wick Structure's heat transfer characteristics

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International Journal of Advanced Nuclear Reactor Design and Technology 2022年第4期4卷 196-204页

作者： Han, Ruiyu Wang, Zetao Guo, Kailun Wang, Chenglong Zhang, Dalin Tian, Wenxi Qiu, Suizheng Su, Guanghui School of Nuclear Science and Technology Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Recently, nanotechnology attracts more and more attention in heat transfer system. Many studies have shown that using nanofluid as the working fluid can improve the thermal performance of the heat pipe. In this paper, the preliminary effort of applying nano-surface engineering on the heat pipe wick to fabricate the nano-structured wick structure has been carried out. Experimental investigation has been performed to determine the effect of the heat source power, mesh aperture and the wick surface structure on the total thermal resistance of the wick structure. When the heat source power increased from 20 W to 30 W, then to 50 W, the evaporation resistance decreases 25.9% and 13.7% respectively, while the conduction resistance increases 24.8% at first and then decreases 9.5%. The evaporation resistance is less with than without the wick structure, and it increases with the increase of mesh aperture. When the mesh aperture increases from 75 μm to 150 μm, then to 460 μm, the evaporation resistance increases 1.9% and 1.7% respectively. Whereas, the wick structure, as well as the mesh aperture have slight influence on the conduction resistance. The experimental results suggest that the nano structure on the surface can efficiently decrease the evaporation resistance but increase the conduction resistance at the same time. Compared to the wick structure with smooth surface, the evaporation resistance of nano-surface deposited by 0.01% TiO2 and 0.02% TiO2 has decreased 4.3% and 15.5%, respectively. This study provides a reference for the preparation of the heat pipe with greater performance in the future. © 2022 Xi'an Jiaotong University

关键词： Wick structure Nano structure Thermal resistance

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Steady thermal hydraulic analysis for a molten salt reactor

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Nuclear Science and Techniques 2008年第3期19卷 187-192页

作者： ZHANG Dalin QIU Suizheng LIU Changliang SU Guanghui State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Xi＇an 710049 China School of Nuclear Science and Technology Xi＇an Jiaotong University Xi＇an 710049 China

The Molten Salt Reactor (MSR) can meet the demand of transmutation and breeding. In this study, theoretical calculation of steady thermal hydraulic characteristics of a graphite-moderated channel type MSR is conducted. The DRAGON code is adopted to calculate the axial and radial power factor firstly. The flow and heat transfer model in the fuel salt and graphite are developed on basis of the fundamental mass, momentum and energy equations. The results show the detailed flow distribution in the core, and the temperature profiles of the fuel salt, inner and outer wall in the nine typical elements along the axial flow direction are also obtained.

关键词：熔盐堆数字模拟热水力分析技术性能

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Thermal-hydraulic performance evaluation of annular fuel based on modified FROBA-ANNULAR

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International Journal of Advanced Nuclear Reactor Design and Technology 2021年 3卷 108-118页

作者： Li, Chenxi Liao, Haoyu Wu, Yingwei Tian, Wenxi Su, G.H. Qiu, Suizheng School of Nuclear Science and Technology Shanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

In this study, based on the modification of the pellet cladding mechanical interaction, gap closure process, and the cladding water corrosion model, Fuel Rod Behavior Analysis-ANNULAR (FROBA-ANNULAR) was uprated. The modified code was verified with FRAPCON-ANNULAR and ABAQUS. The verification calculation was under low power density when both two gaps were open. The calculation results showed good agreement. The modified code was then utilized to evaluate the annular fuel behavior, compared with the original code FROBA-ANNULAR. In this study, the annular fuel exhibits a much lower peak fuel temperature(about 900K). The different results for heat flux fraction(0.55 for the original code, 0.66 for the modified code) indicated that the gap closure process strongly affected the movement of the adiabatic pellet line. The internal pressure results (7.5 MPa for the original code, 6 MPa for the modified code) were also affected by the different assumptions. The results also showed that Zr's oxidation thickness and hydrogen concentration were related to both time and temperature. The higher the temperature was, the larger the oxidation rate was when the transition thickness was reached. © 2021

关键词： Heat flux

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Development of a three-dimensional method for thermal-hydraulics/neutronics coupling analysis and its application on CFETR helium-cooled solid breeder blanket

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International Journal of Advanced Nuclear Reactor Design and Technology 2021年 3卷 154-165页

作者： Lian, Qiang Tian, Wenxi Qiu, Suizheng Su, G.H. Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Blankets are of practical importance in the fusion reactor due to their main functions for engineering application. As the fusion power designed for the Chinese Fusion engineering Test Reactor (CFETR) is increased from 200 MW to 1.5 GW during its phase II operation, more challenges are issued for blankets from the points of view of thermal-hydraulics, neutronics, mechanics, and safety. In this paper, the Coupling Analysis of Thermal-hydraulics and Neutronics Interface Code (CATNIC) was developed using the user-defined function (UDF) in the CFD software FLUENT. The explicit coupling scheme based on cell-to-cell mapping approach was adopted to transfer data between neutronics calculation and thermal-hydraulics simulation. Three-dimensional thermal-hydraulic model and neutronics model were established using Fluent and MCNP4C, respectively. The helium-cooled solid breeder (HCSB) blanket of CFETR was simplified as a slice model to reduce the computing resources. With the slice model of CFETR HCSB blanket, the coupling analysis was carried out using the developed CATNIC. The calculation results from coupling and non-coupling analyses were compared to verify the feasibility of the coupling method in this study. As the helium coolant was considered as the transparent medium for neutron, the thermal-hydraulic and neutronics analyses were both converged after two iterations. However, using the developed coupling method in this study, the detailed change of tritium production ratio (TPR) and nuclear heat deposition in different parts of the blanket was revealed, which could provide important guidance for the design of the distribution for both coolant and purge gas. © 2021 Xi'an Jiaotong University

关键词： Coolants

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EFFECT OF INNER FIN TUBE STRUCTURE ON COMPREHENSIVE PERFORMANCE OF SUPERCRITICAL CARBON DIOXIDE AND LEAD BISMUTH EUTECTIC HEAT EXCHANGER

EFFECT OF INNER FIN TUBE STRUCTURE ON COMPREHENSIVE PERFORMA...

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ASME 2023 Heat Transfer Summer Conference, HT 2023

作者： Shuhan, Liu Ji’an, Liu Qingjiang, Liu Xianliang, Lei State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

ISBN: (纸本)9780791887165

In the combined system of lead cooled fast reactor (LFR) and supercritical carbon dioxide (S-CO2) Brayton cycle, the intermediate heat exchanger plays a key role in the whole power system. However, the existing heat exchanger can not meet the trend of miniaturization of lead cooled fast reactor. Considering the thermo-physical properties and heat transfer behaviors in both S-CO2 and liquid lead bismuth eutectic (LBE) are significantly different, an asymmetric compact coupled heat exchanger learning from Honeycomb structure is proposed. Through numerical simulation, it is found that the thermal resistance mainly exists in the cold side. In order to enhance the heat transfer at the S-CO2 side, the fin tube is adopted at the cold side. The results show that the heat transfer performance and friction factor of the heat exchanger increase with the increase of fin height, width and number of fins due to the increase of heat transfer area. When the fin height is increased, PEC gradually increases at low inlet velocity, and then decreases at high inlet velocity;When the fin width is increased, PEC increases first and then decreases at low inlet velocity, and decreases gradually at high inlet velocity;With the increase of the number of fins, PEC showed an increasing trend at different inlet velocities. © 2023 by ASME.

关键词： Supercritical fluid extraction

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Mitigating check valve slamming and subsequentwater hammer events for PPFS using MOC

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Nuclear Science and Techniques 2009年第2期20卷 118-123页

作者： TIAN Wenxi SU Guanghui WANG Gaopeng QIU Suizheng XIAO Zejun State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and TechnologyXi＇an Jiaotong University Xi＇an 710049 China National Key Laboratory of Bubble Physics ＆ Natural Circulation Nuclear Power Institute of China Chengdu 610041 China

The method of characteristic(MOC) was adopted to analyze the check valve-induced water hammer behaviors for a Parallel Pumps Feedwater System(PPFS) during the alternate startup *** motion of check valve disc was simulated using inertial valve *** parameters including the pressure oscillation,local flow velocity and slamming of the check valve disc *** been *** results showed that severe slamming between the valve disc and valve seat occurred during the alternate startup of parallel *** induced maximum pressure vibration amplitude is up to 5.0 *** scheme of appending a damping torque to slow down the check valve closing speed was also performed to mitigate of water *** has been numerically approved to be an effective approach.

关键词：止回阀建设部事件水锤泵给水系统启动过程压力振动瞬态参数

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THERMAL-HYDRAULIC ANALYSIS OF THE COOLING WALL IN ULTRA SUPERCRITICAL COAL-FIRED GENERATION PLANTS DURING DEEP PEAKING

THERMAL-HYDRAULIC ANALYSIS OF THE COOLING WALL IN ULTRA SUPE...

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ASME 2024 power Conference, power 2024

作者： Wang, Dengliang Zhao, Yongliang Chen, Weixiong Wang, Chaoyang Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

ISBN: (纸本)9780791888186

Due to increasingly severe environmental and climate concerns currently, renewable energy is highly penetrated around the world. However, given the intermittency and instability of renewable energy, coal-fired generation plants urgently need to undertake deep peak shaving tasks, resulting in the frequent load cycling transient processes of units. It will have a significant effect on the safe operation of the boiler components, especially for the hydrodynamic instability of cooling wall within the boiler. This paper takes a 1100 MW ultra-supercritical primary reheat coal-fired generation plants as the research object. In accordance with the heating load distribution characteristics of cooling wall, a hydrodynamic characteristic calculation model of cooling wall within the boiler is constructed based on the mass conservation, momentum conservation and energy conservation equations, which introduces numerous empirical correlations available for heat transfer and hydraulic resistance calculation at the same time. The working fluid temperature in the direction of cooling wall height at 100% THA, 75% THA, 50% THA, 40% THA and 30% THA, as well as the metal temperature of the inner, outer and fin tube walls are analyzed. The changes in metal wall temperature of cooling wall under different load cycling rates are obtained during the low load operating range of 50% THA to 30% THA. Ultimate load cycling rates of the coal-fired generation plants without causing the overtemperature issue of cooling wall is obtained. Finally, when the revised fuel supply control strategy is adopted, it is able to significantly reduce the maximum metal wall temperature during the rapid load cycling process. The maximum load cycling rate is increased from 2.5% Pe/min to 3.0% Pe/min for the loading up process. Copyright © 2024 by ASME.

关键词： Coal

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Optimization of the concentration field in a suspended photocatalytic reactor with the periodically changing solar irradiation

Optimization of the concentration field in a suspended photo...

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26th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2013

作者： Cao, Fei Zhao, Liang Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

Feasibility of the solar photocatalysis has been validated theoretically and experimentally. Main concerns on the solar photocatalysis in the solutions are: the mass transfer limitation between the photocatalyst and the solution, and the concentration or radiation distribution in the photoreactors. Most researches concentrated their research on one aspect. There is limited research considering variable catalysis concentrations together with the changing solar radiation. However, outdoor solar photocatalysis devices, i.e. for hydrogen production or waste water degradation, would practically face this phenomenon. In the present study, the photon absorption in a suspended photocatalytic reactor was simulated by adopting Monte Carlo method and the six-flux radiation absorption-scattering model. Different photocatalyst concentrations were taken into account. Simulation results indicated that the photon absorption had a close relationship with the concentration distribution of the photocatalysts, and that there is an optimal concentration gradient in the photoreactor leading to the maximum photon absorption. Accordingly, the concentration field is optimized according to the changing solar irradiation. The present work is expected to be of effective value for obtaining the optimal operating parameters for industrial solar photocatalytic applications.

关键词： Solar radiation

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THE FLEXIBILITY ENHANCEMENT OF SUBCRITICAL COAL-FIRED power PLANTS: CONTROL STRATEGY OPTIMIZATION FOR LIVE AND REHEAT STEAM TEMPERATURE

THE FLEXIBILITY ENHANCEMENT OF SUBCRITICAL COAL-FIRED POWER ...

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ASME 2024 power Conference, power 2024

作者： Chen, Chen Liu, Ming Wang, Chaoyang Zhao, Yongliang Yan, Hui Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

ISBN: (纸本)9780791888186

With the increasing penetration of renewable power, flexible power sources are urgently required by the power grid to balance the supply and demand sides. Therefore, the operational flexibility of subcritical coal-fired power plants should be further enhanced. In this study, dynamic models of a reference 330MW subcritical coal-fired power plant were developed and validated. The load ramp performances of the reference plant were simulated. The maximum ramp rates during loading down processes were 2%Pe/min and 1.5%Pe/min in 75% -50% and 50% -40% load cycling ranges, respectively, and the maximum ramp rate during loading up processes is 1.5%Pe/min. That the live steam and reheat steam temperatures exceeding their thresholds limits for the load ramp rates. The subcritical power unit has a steam drum, serving as a substance and energy storage device, and allows partial decoupling of feedwater flow and coal flow. Consequently, an enhanced steam temperature control strategy, facilitated by adjusting the feedwater flow rate during the load ramp processes, was proposed. The feedwater flow rate is appropriately regulated during load cycling dynamic processes to assist the control of live steam and reheat steam temperatures. The models to obtain the live steam and reheat steam temperature variations influenced by the feedwater flow rates are developed, and implemented in the control strategy. Then, simulations on the reference power plant with the enhanced control strategy were conducted, and the temperature overshoots have been effectively suppressed. As a result, the load ramp rate is increased. For example, in the load cycling range of 75%-40%, the overall unit ramp rate is increased by 1%Pe/min, achieving an enhancement in the operational flexibility of subcritical units. Copyright © 2024 by ASME.

关键词： Coal

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