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An Operation Optimization of Cooling System for Reactor Shutdown in Pebble Bed Gas-Cooled Reactor

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SSRN 2024年

作者： Liu, Junfeng Wang, Chenglong Qiu, Suizheng Wang, Boyuan Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology Shaanxi Engineering Research Center of Advanced Nuclear Energy Xi’an Jiaotong University Xi’an710049 China Xi’an Thermal Power Research Institute Co. Ltd Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering China

For the emergency shutdown of a high temperature gas-cooled reactor pebble-bed module (HTR-PM) in its operation conditions, in the current design method with a low-flow auxiliary steam cooling technical solution, there are some security and economic issues, i.e. high thermal shock, long cooling time, and temperature drop rate exceeding the limit. To solve these problems, an optimized design method for the shutdown cooling system is presented. Through a simulation model of the shutdown cooling system based on Matlab/Simulink, the dynamic characteristics of the shutdown cooling system in its operation conditions are obtained, involving shutdown, low flow cooling, and water supply start-up stages. The results showed that with the optimized design method, the safety of the core and steam generator can both be ensured during the cooling process, and the cooling rate is significantly improved. Therefore, the optimized design method is feasible and advanced. © 2024, The Authors. All rights reserved.

关键词： Cooling

Transient gas/liquid two-phase flow in a pipeline-riser system after the change of inlet flow rates

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Multiphase Science and Technology 2020年第2期32卷 25-46页

作者： Zou, Suifeng Liu, Weizhi Xu, Qiang Xie, Xiangdong Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China Wuhan Second Ship Design and Research Institute Wuhan China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Transient gas/liquid two-phase flow caused by the change of inlet gas and/or liquid flow rates was experimentally studied in a 380-meter-long pipeline-riser system with a vertical riser of 21.5 meters in height. Results showed that, for the transient processes with the same median flow rates, the rise of flow rates was likely to result in shorter duration time compared to the fall of flow rates. Apart from the manner of change, the duration time was also closely related to the flow mechanism, which varied with the global flow regime. As a consequence, the transient process lasted a longer time around the transition boundary of stable regime and the severe slugging regime;whereas, the transient process would be shorter if the regime was an irregular oscillation;and the longest transient process was found at very low gas and liquid flow rates. As for the prediction of duration time of both the entire transient process and the transition to undesirable flow regimes, the support vector machine turned out to be much more suitable than the log-linear regression. In addition, some similarities of pressure drop signals were found between the transition to unstable and irregular flow regimes and the steady state of these regimes. Since the method for fast recognition of a steady global flow regime has already been developed, it becomes possible to forecast the transition to these undesirable flow regimes through the modification of the recognition method. © 2020 Begell House Inc.. All rights reserved.

关键词： flow rate

A simple analytical model to predict liquid unloading in the horizontal gas well

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Journal of Hydrodynamics 2021年第5期33卷 1056-1064页

作者： Zhi-bin Wang Jin-quan Ling Tian-li Sun Hong-yan Shi Guo Zhu State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChendu 610500China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China No 2 Gas Production PlantSouthwest Oil and Gas CompanySINOPECLangzhong 637400China Infrastructure Department Southwest Oil and Gas CompanySINOPECChengdu 610041China

An accurate prediction of the critical gas velocity for the liquid loading is of great importance for operators to select the tubing diameter for the newly drilled gas wells,or to optimize the production rate for production *** is clear from previous experimental studies of the liquid entrainment rate in the gas core that the liquid is mainly carried in the form of film under the critical condition of the liquid loading *** is more reasonable to establish a mathematical model based on the film reversal rather than based on the droplet *** our previous paper entitled“Prediction of the critical gas velocity of liquid unloading in the horizontal gas well”,a new analytical model was established based on the force balance between the gas-liquid interfacial friction force and the bottom film gravity,but the model is not very convenient to use because of the complexity of calculating the average film *** the present study,a new method is proposed to calculate the average film thickness from the bubble drift velocity in the mixture,so the new analytical model becomes much easier to *** new analytical model is evaluated against 103 sets of experimental data,the data in 124 vertical gas wells and one horizontal gas ***,the effect ofthe liquid loading on the production of the horizontal gas well is also analyzed.

关键词： Horizontal gas well inclined annular flow liquid-film thickness liquid unloading

Effect of ammonium ion on the corrosion behavior of Ni 2 FeCrMo 0.2 high-entropy alloy in simulated haze solution

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Journal of Materials Research and Technology 2025年 37卷 146-156页

作者： Kai Wang Qilong Zhao Yanhui Li Ruidong Li Qipeng Xu State Key Laboratory of Eco-hydraulics in Northwest Arid Region Xi'an University of Technology No.5 Jinhua South Road Xi'an 710048 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Xi'an 710049 China School of Chemical Engineering Northwest University No.229 Taibai North Road Xi'an 710069 China

Various constituents of PM 2.5 in haze can accelerate metal corrosion, but traditional carbon steel and stainless steel perform poorly in such complex corrosive environments, and thus developing new corrosion-resistant materials are of great importance for mitigating haze-induced corrosion. The corrosion behavior of Ni 2 FeCrMo 0.2 alloy in haze-simulating aqueous solutions containing various constituents of PM 2.5 in haze is investigated. By the coupling analysis of electrochemical experiments, corrosion morphology, and corrosion product film, the influence of NH 4 + concentration on the corrosion mechanism related to multi-principal metal elements is revealed. The results show that the Ni 2 FeCrMo 0.2 alloy exhibits superior corrosion resistance compared with 2205 duplex stainless steel. As the NH 4 + concentration increases, the corrosion rate increases initially but then decreases at higher NH 4 + concentrations, and the corrosion morphology also confirms this changing trend. The corrosion prompt is primarily due to the lower solution pH caused by the hydrolysis reaction of NH 4 + . In contrast, the corrosion inhibition at higher NH 4 + concentration is attributed to the passive film on the alloy surface, which is composed of Cr, Fe, Mo, Ni, and their oxides, with the presence of Mo elements forming a unique structure that improved the density and stability of the film, thereby inhibiting the growth of corrosion pits. The changing trend of corrosion film resistance and corrosion product film thickness agrees well with this change in corrosion rate. This study provides an insightful understanding of the corrosion behavior of multi-principal alloy materials in haze environments, which is crucial for the corrosion protection design of metal equipment materials.

关键词： Haze constituents Corrosion High entropy alloy Passive film

Water Washing of Biomass and Biochar

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SSRN 2022年

To investigate the differences in organics composition between leachates of biomass and biochar, four biomass materials and the corresponding biochar are water washed. GC-MS is employed to characterize the distributions of organic components in leachates. Raw and washed biomass, and biomass leachates dried at 333 K are sent for TG/DTG analysis. The results show that corn and sorghum stalks should be washed after the high-temperature pyrolysis at 303 K, with aromatic hydrocarbon contents of 11.00% and 29.95%, respectively. It is proposed that wheat straw and rice husk should be washed directly. Considering the contents of alkanes, cycloalkanes, and heterocyclic hydrocarbon in leachates, biomass should be pyrolyzed at a relatively low temperature and then be washed. It is recommended to wash biomass directly to inhibit the acidic organic release. Washed and raw biomass samples have the similar DTG curves. The combustion of dried leachate is more complicated, with one or two peaks during the third stage. The activation energy follows an order of washed biomass > raw biomass > biomass leachate. © 2022, The Authors. All rights reserved.

关键词： Biomass

Characteristics and Prediction Model of Co-Pyrolysis of Sewage Sludge and Camellia Seed Shell

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SSRN 2022年

作者： Wang, Bo Liu, Yinhe Guan, Yu Feng, Yiwei Pan, Hejitian State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi’an710049 China

Tar is an undesired product in the process of sewage sludge pyrolysis, which affects the normal operation of the equipment. In this paper, the characteristics of co-pyrolysis of sewage sludge and camellia seed shell for tar reduction and syngas production were explored. The content and composition of tar and pyrolysis gas co-pyrolyzed with different proportions of sewage sludge (JAS) and camellia seed shell samples (CSS) were studied. The weight loss characteristics of the samples were studied by thermogravimetric experiment, and the synergistic effects of different stages were analyzed. The performances of back propagation (BP) neural network and particle swarm optimization-back propagation neural network (PSO-BP) in reflecting the nonlinear relationship between temperature, mixing ratio, heating rate and remaining weight were compared. The results show that the tar yield was the lowest when 40JAS60CSS was pyrolyzed, which could alleviate the serious problems caused by the tar. Compared with the JAS single pyrolysis, the co-pyrolysis of JAS and CSS improved the content of PAHs and reduced the content of aliphatic hydrocarbons in the tar. The inhibition and promotion effects of co-pyrolysis would be transformed into each other with the progress of the pyrolysis, and the transformations were concentrated in the S 2 stage where the weight loss of the sample is the largest. The constructed PSO-BP-30 model contained two hidden layers, each with 12 neurons, which accurately reflected the nonlinear relationship between the temperature, mixing ratio, heating rate and residual weight. © 2022, The Authors. All rights reserved.

关键词： Pyrolysis

Study of Saturated Pool Boiling Heat Transfer Characteristics of R1233zd(E) on Aluminum-Based Micro-Pin Finned Surfaces

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SSRN 2024年

作者： Yang, Xiaoping Bu, Shichao Jiang, Zhuye Chen, Hongqiang Sun, Zhen Zhang, Yonghai Wei, Jinjia School of Chemical Engineering 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 State Key Laboratory of Mobile Network and Mobile Multimedia Technology ZTE Corporation hillsides China

With the continuous development of chip integration and information technology, the heat dissipation has become a major limitation on the performance of electronic devices such as 5G base station, data center and so on, and meanwhile a challenge of conventional single-phase convection cooling methods. Boiling is prospective in high heat flux cooling and energy saving due to the usage of latent heat. R1233zd(E), an environmentally friendly refrigerant (GWP=1, ODP=0) with a freezing point of -107°C, is a potential working fluid in phase-change heat sinks for geographical applications. Nevertheless, the poor boiling performance of R1233zd(E) on plain surface due to the limitation in thermophysical properties must be enhanced. Moreover, conventional heat sinks are mostly copper-based, which are inconvenient for transportation and installation, and costly for production as well. In this work, micro pin fins in the range of 100-500 μm are fabricated on the aluminum surface to enhance the pool boiling of R1233zd(E). Moreover, the influence of their size and saturation pressure on the bubble behavior, critical heat flux (CHF) and heat transfer coefficient (HTC) is experimentally and theoretically investigated. The results show that the increase of pressure, as well as the ensuing various nucleation site and capillary effect to rewet the evaporation region, can lead to an increase in the CHF and HTC. Notably, the 150-200 μm micro pin-finned surfaces reaches the highest CHF and 100 μm one owns the highest HTC, which is 214% and 383% higher than that of plain surface, respectively. BY considering the balance of capillary effect and bubble convolution effect, a model of CHF is proposed to reveal the mechanism of optimum size of the micro pin fins. The predicted CHFs have an inaccuracy of less than ±20% comparing to experimental values. This paper makes up for the lack of basic experimental data on pool boiling of R1233zd(E) on aluminum surface, which thus provides guidance for

关键词： Heat flux

P-Type Chemical Doping-Induced High Bipolar Electrical Conductivities in a Thermoelectric Donor–Acceptor Copolymer

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CCS Chemistry 2021年第10期3卷 2482-2493页

作者： Jing Wang Yizhuo Wang Qing Li Zhanchao Li Kuncai Li Hong Wang Frontier Institute of Science and Technology Xi’an Jiaotong UniversityXi’an 710054 State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710054

Typically,conducting polymers transfer either electrons or *** is rare to see high bipolar(p-and n-type)electrical conductivities within a single bulk doped organic polymer without the assistant of gate ***,we report that FeCl3-doped solutionprocessable D–A copolymer poly(2,5-bis(2-octyldo decyl)-3,6-di(thiophen-2-yl)diketopyrrolo[3,4-c]pyrrole-1,4-dione-alt-thieno[3,2-b]thiophen)(DPPTTT)could exhibit a high p-type electrical conductivity of 130.6 S/cm and a good n-type electrical conductivity of 14.2 S/cm by engineering the doping level.

关键词： polarity switching donor-acceptor copoly mer thermoelectric organic diode p-ty pe doping

A study on free radical behaviors and reactions in supercritical water using quantum chemical simulation

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Journal of Molecular Liquids 2025年 419卷

作者： Ding, Weijing Takahashi, Osamu Wang, Junying Jin, Hui School of Transportation and Vehicle Engineering Shandong University of Technology Shandong Zi'bo255000 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China of Advanced Science and Engineering Hiroshima University Higashi-Hiroshima739-8526 Japan

Supercritical water (SCW) gasification is one of clean and efficient utilization way of biomass, other organic matters or coal for hydrogen production, in which radical reactions studies in SCW are limited but crucial. Density-functional tight-binding (DFTB) molecular simulation is one of efficient and convenient approaches to investigate these microscopic processes. Therefore, free radical reactions in severe SCW environment were investigated via DFTB calculations in this work. The results showed that the order of the free radicals containing bond cleavages reacted in SCW environment was ·OH, ·CH, ·CH2, ·HO2, ·CH3 and ·C6H5 under the same conditions. The reaction processes of different radicals in SCW were obtained. ·H was the most active free radical of reactions. This work is expected to understand the properties of free radicals in SCW better and explore intrinsic reaction mechanisms, which may provide a theoretical support for accomplishing efficient and low-carbon complete SCW gasification for hydrogen production. © 2024 Elsevier B.V.

关键词： Free radical Gasification Hydrogen production Reaction Supercritical Water (SCW)