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Numerical analysis on heat transfer enhancement by longitudinal vortex based on field synergy principle

中国高等学校学术文摘·能源与动力工程 2007年第3期1卷 365-369页

作者： WU Junmei TAO Wenquan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China School of Environment and Chemical Engineering Xi'an Polytechnic UniversityXi'an 710048China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

Three-dimensional numerical simulation results are presented for a fin-and-tube heat transfer surface with vortex *** effects of the Reynolds number (from 800 to 2 000) and the attack angle (30° and 45°) of a delta winglet vortex generator are *** numerical results are analyzed on the basis of the field synergy principle to explain the inherent mechanism of heat transfer enhancement by longitudinal *** secondary flow generated by the vortex generators causes the reduction of the intersection angle between the velocity and fluid temperature *** addition,the computational evaluations indicate that the heat transfer enhancement of delta winglet pairs for an aligned tube bank fin-and-tube surface is more significant than that for a staggered tube bank fin-and-tube *** heat transfer enhancement of the delta winglet pairs with an attack angle of 45° is larger than that with an angle of 30°.The delta winglet pair with an attack angle of 45° leads to an increase in pressure drop,while the delta winglet pair with the 30°angle results in a slight *** heat transfer enhancement under identical pumping {1. condition for the attack angle of 30° is larger than that for the attack angle of 45°either for staggered or for aligned tube bank arrangement.

关键词： longitudinal vortex heat transfer enhancement field synergy principle

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The dust emission law in the wind erosion process on soil surface

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Science China(Physics,Mechanics & Astronomy) 2009年第2期52卷 258-269页

作者： XING Mao1.& GUO LieJin2 1.Mining Technology Institute, Taiyuan University of Technology, Taiyuan 030024, China 2 state {1. laboratory of multiphase flow in power engineering, Xi’an Jiaotong University, Xi’an 71.049, China Mining Technology Institute Taiyuan University of Technology Taiyuan 030024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

The dust emission models to date cannot describe the relation between the transport rate of different sized grains and their grain size composition in soil surface, so Aeolian grain transport on a soil-like bed composed of fine sand and silt powder was measured in a wind tunnel. Six types of soil-like beds with different silt fractions have been tested in this experiment. The mass flux profiles of silt dust and sand grains are much different due to their different motion modes. Analysis of the vertical distribution of the powder and sand grains reveals that for a given soil bed, the ratio of the horizontal dust flux to the horizontal sand flux is directly proportional to their mass ratio in the bed. The dust flux is closely linked to the sand flux by the bombardment mechanism. For a given wind velocity and grain size of the bed, the slopes of the vertical mass flux profiles of sand grains larger than 1.0 μm are nearly equal in a log-linear plot and the ratio between the fraction of transport rate of each size group to the whole transport rate and the mass fraction of each size group in the bed is a constant only dependent on grain size. With this law, the transport rate of dust and different sized grains can be related with the grain size composition in the soil surface.

关键词： wind erosion dust transport rate grain size

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CFD simulation of thermal hydraulic characteristics in a typical upper plenum of RPV

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Frontiers in Energy 2021年第4期15卷 930-945页

作者： Mingjun WANG Lianfa WANG Yingjie WANG Wenxi TIAN Jian DENG Guanghui SU Suizheng QI State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and TechnologyXi’an Jiaotong UniversityXi’an 710049China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of ChinaChengdu 610213China

A comparative computational fluid dynamics(CFD)study was conducted on the three different types of pressurized water reactor(PWR)upper plenum,named TYPE 1.support columns(SCs)and control rod guide tubes(CRGTs)with two large windows),TYPE 2(SCs and CRGTs without windows),and TYPE 3(two parallel perforated barrel shells and CRGTs).First,three types of upper plenum geometry information were collected,simplified,and adopted into the BORA facility,which is a 1.5 scale system of the four-loop PWR ***,the geometry,including the upper half core,upper plenum region,and hot legs,was built using the Salome *** that,an unsteady calculation to simulate the reactor balance operation at hot full power scenario was ***,the differences of {1.rate distribution at the core outlet and temperature distribution and transverse velocity inside the hot legs with different upper plenum internals were *** results suggest that TYPE 1.upper plenum internals cause the largest {1.rate difference at the core outlet while TYPE 3 leads to the most even distributed *** distribution and evolution pattern of the tangential velocity inside hot legs is highly dependent on the upper plenum *** counter-rotating swirls exist inside the TYPE 1.hot leg and only one swirl revolving around the hog leg axis exist inside the TYPE 2 hot *** TYPE 3,two swirls like that of TYPE 1.rotating around the hot leg axis significantly increase the temperature homogenization *** research provides meaningful guidelines for the future optimization and design of advanced PWR upper plenum internal structures.

关键词： pressurized water reactor(PWR) upper plenum internal structures temperature distribution computational fluid dynamics(CFD)

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Thermal physical applications of carbon dioxide:Recent progress,challenges and perspective

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Resources Chemicals and Materials 2023年第4期2卷 288-311页

作者： Pei Duan Kun Jiang Jinwen Shi Hui Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityShaanxi710049PR China

Carbon dioxide(CO_(2))is one of the main factors contributing to the greenhouse *** dependence on fossil fuels has led to increasing levels of carbon dioxide in the atmosphere every *** it is far from enough to solve the climate problem by reducing the consumption of fossil fuels to cut down carbon dioxide *** recent years,a series of researches on Carbon Capture,Utilization and Storage(CCUS)have been carried out in various countries around the ***_(2) is a nontoxic,tasteless and stable gas at normal ***,when it reaches supercritical state after rising temperature and pressure,it has the characteristics of low viscosity,high diffusivity and high density,and is widely used in green,pollution-free and efficient development *** of these unique properties,supercritical carbon dioxide(sCO_(2))has attracted more and more attention from ***_(2) has been widely used in many aspects by virtue of its high solubility and easy *** from previous reviews which only introduced the application of sCO_(2) property,this paper introduces the current research status of the application of the thermodynamic property of carbon dioxide in extraction,dyeing,pharmaceutical,{1. generation,heat transfer and exploitation of unconventional oil and gas,and mainly analyzes each application in detail from the aspects of working mechanism and improving working ***,the research direction and problems needed to be solved for the application of CO_(2) thermal physics are proposed,which pave the way for other new applications.

关键词： Utilization of CO_(2) Supercritical state Thermal physical applications Extraction Heat transfer Oil and gas exploitation

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Experimental investigation of particle velocity distributions in windblown sand movement

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Science China(Physics,Mechanics & Astronomy) 2008年第8期51卷 986-1000页

作者： KANG LiQiang GUO LieJin LIU DaYou State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China Division of Engineering Sciences Institute of MechanicsChinese Academy of SciencesBeijing 100190China

With the PDPA(Phase Doppler Particle Analyzer) measurement technology,the probability distributions of particle impact and lift-off velocities on bed surface and the particle velocity distributions at different heights are detected in a wind tunnel. The results show that the probability distribution of impact and lift-off velocities of sand grains can be expressed by a log-normal function,and that of impact and lift-off angles complies with an exponential function. The mean impact angle is between 28° and 39°,and the mean lift-off angle ranges from 30° to 44°. The mean lift-off velocity is 0.81.0.9 times the mean impact velocity. The proportion of backward-impacting particles is 0.05-0.1.,and that of backward-entrained particles ranges from 0.04 to 0.1.. The probability distribution of particle horizontal velocity at 4 mm height is positive skew,the horizontal velocity of particles at 20 mm height varies widely,and the variation of the particle horizontal velocity at 80 mm height is less than that at 20 mm height. The probability distribution of particle vertical velocity at different heights can be described as a normal function.

关键词： windblown sand movement probability distribution particle velocity

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Estimation of LISS(local input-to-state stability) properties for nonlinear systems

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Science China(Technological Sciences) 2010年第4期53卷 909-917页

作者： WU ShengYu,MEI ShengWei & ZHANG XueMin state {1. laboratory of power Systems,Department of Electrical engineering,Tsinghua University,Beijing 1.0084,China 1. State Key Laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing 100084 China

Compared with input-to-state stability(ISS) in global version,the concept of local input-to-state stability(LISS) is more relevant and meaningful in *** key of assessing LISS properties lies in investigating three main ingredients,the local region of initial states,the local region of external inputs and the asymptotic *** is the objective of this paper to propose a numerical algorithm for estimating LISS properties on the theoretical foundation of quadratic form LISS-Lyapunov *** developments of linear matrix inequality(LMI) methods,this algorithm is effective and powerful.A typical power electronics based system with common DC bus is served as a demonstration for quantitative results.

关键词： locally input-to-state stability LISS-Lyapunov function linear matrix inequality

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Gas emission source term estimation with 1.step nonlinear partial swarm optimization-Tikhonov regularization hybrid method

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Chinese Journal of Chemical engineering 2018年第2期26卷 356-363页

作者： Denglong Ma Wei Tan Zaoxiao Zhang Jun Hu School of Food Equipment Engineering and Science Xi'an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University School of Chemical Engineering and Technology Xi'an Jiaotong University School of Chemical Engineering Northwest University

Source term identification is very important for the contaminant gas emission event. Thus, it is necessary to study the source parameter estimation method with high computation efficiency, high estimation accuracy and reasonable confidence interval. Tikhonov regularization method is a potential good tool to identify the source parameters. However, it is invalid for nonlinear inverse problem like gas emission process. 2-step nonlinear and linear PSO （partial swarm optimization）-Tikhonov regularization method proposed previously have estimated the emission source parameters successfully. But there are still some problems in computation efficiency and confidence interval. Hence, a new 1.step nonlinear method combined Tikhonov regularizafion and PSO algorithm with nonlinear forward dispersion model was proposed. First, the method was tested with simulation and experiment cases. The test results showed that 1.step nonlinear hybrid method is able to estimate multiple source parameters with reasonable confidence interval. Then, the estimation performances of different methods were compared with different cases. The estimation values with 1.step nonlinear method were close to that with 2-step nonlinear and linear PSO-Tikhonov regularization method, 1.step nonlinear method even performs better than other two methods in some cases, especially for source strength and downwind distance estimation. Compared with 2-step nonlinear method, 1.step method has higher computation efficiency. On the other hand, the confidence intervals with the method proposed in this paper seem more reasonable than that with other two methods. Finally, single PSO algorithm was compared with 1.step nonlinear PSO-Tikhonov hybrid regularization method. The results showed that the skill scores of 1.step nonlinear hybrid method to estimate source parameters were close to that of single PSO method and even better in some cases. One more important property of 1.step nonlinear PSO-Tikhonov regularization metho

关键词： Parameter estimation Parameter regularization method Source identification Inverse problem

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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 {1., mesh aperture and the wick surface structure on the total thermal resistance of the wick structure. When the heat source {1. increased from 20 W to 30 W, then to 50 W, the evaporation resistance decreases 25.9% and 1..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 1.0 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 1..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 {1. 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 {1. distribution in the core, and the temperature profiles of the fuel salt, inner and outer wall in the nine typical elements along the axial {1. 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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