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Energy analysis of spray flash evaporation from superheated upward jets

APPLIED THERMAL engineering 2019年 148卷 704-713页

作者： Cai, Benan Wang, Qingqing Yin, Songtao Gu, Hongfang Wang, Haijun Zhen, Hongdong Zhang, Lei Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China China Nucl Power Design Co Ltd Shenzhen 518000 Peoples R China

Flash evaporation is widely used in desalination technologies. The flash evaporation from upward and downward jets shows different characteristics. To study the upward flash evaporation, a model based upon droplet analysis is developed. The present model takes the droplet motion, droplet size variation and droplet temperature into consideration. The model is validated against the corresponding experimental results from previous literature and the calculated results from the model coincide with the experimental results. The dimensionless temperature profiles of the upward and downward flash evaporation are compared. Employing this model, the influences of the injection pressure, evaporation chamber pressure and flow velocity on the energy utilization efficiency and spray flash speed are investigated. The critical time and critical distance are also compared and analyzed.

关键词： Upward flash evaporation Temperature gradient Energy utilization efficiency Spray flash speed

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Effect of hydrogen enrichment and electric field on lean CH4/air flame propagation at elevated pressure

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2019年第30期44卷 15962-15972页

作者： Wang, Jinhua Li, Yiming Xia, Hao Ju, Rongyuan Zhang, Meng Mu, Haibao Huang, Zuohua Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ State Key Lab Elect Insulat & Power Equipment Sch Elect Engn Xian 710049 Shaanxi Peoples R China

Electric assisted combustion for hydrogen enriched hydrocarbons may even extend the lean burn limit and provide the further improvement on combustion stability. This study investigates the effect of hydrogen enrichment and DC electric field on lean CH4/air flame propagation. Electric field inside the chamber was generated by mesh and needle electrodes. Effect of hydrogen enrichment on the ion mole fraction in the flame was discussed based on reaction mechanism included neutral and ion reactions. The flame propagation images, flame displacement speed were used to evaluate the combined influences of hydrogen enrichment and electric field on propagating flame. Results showed that the hydrogen addition would increase positive ions mole fraction and the peak value is mainly determined by H3O+. This would be due to that CH increases with hydrogen fraction, which is the main species in the initial reaction for the ion reactions. Electric field effect about flame propagation was suppressed with hydrogen addition due to the competition between the increment in ion mole fraction and the decrement in flame time. Electric assisted combustion is more evident at leaner conditions and elevated pressure. The ratio of ionic wind velocity to flow velocity may be the determined factor to predict the electric field effect about propagating flame. The tendency based on this ratio is in accordance with the experimental results for various hydrogen fraction and equivalence ratio at elevated pressure. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Hydrogen enrichment Electric assisted combustion Ionic wind Ion mole fraction Flame propagation Elevated pressure

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Rate coefficients for 1,2-dimethyl-allyl + HO₂/O₂ and the implications for 2-methyl-2-butene combustion

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COMBUSTION AND FLAME 2021年 230卷 111433-111433页

作者： Yin, Geyuan Goldsmith, Claude Franklin Chen, Xi Hu, Erjiang Huang, Zuohua Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Brown Univ Sch Engn Chem & Environm Engn Providence RI 02912 USA Brown Univ Dept Chem Providence RI 02912 USA

A detail investigation is presented on the reaction of 1,2-dimethyl-allyl with HO2, including bimolecular reactions of aC(5)H(9)-c with HO2, thermal decomposition reactions of aC(5)H(9)OOH, and the subsequent decomposition and isomerization reactions of C5H9O based on theoretical work. In addition, the reaction of aC(5)H(9)-c with O-2 and the resulting peroxy-radical chemistry is presented. The majority of the stationary points are obtained at CCSD(T)-F12/cc-pVTZ-F12//M06-2X/6-311G(d,p) level, with barrierless reaction and some transition states using multireference method. Microcanonical rate theory and the master equation are used to determine the temperature- and pressure-dependent rate coefficients, as implemented in a RRKM/ME code. Uncertainty analysis for energy barrier and Delta E-down were conducted. The newly developed submechanisms for the reactions of 1,2-dimethyl-allyl with HO2 and O-2 are added to a previous literature model for 2-methy-butene. The results show that at low pressure/high temperature, the reaction aC(5)H(9)-c with HO2 would directly decompose to aC(5)H(9)O + OH, which, though technically a chain propagating reaction, and significantly increases the reactivity of the system. The updated mechanism is in much better agreement with the available experimental data. (C) 2021 Published by Elsevier Inc. on behalf of The Combustion Institute.

关键词： 1,2-dimethyl-allyl + HO2/O-2 Quantum calculation Rate coefficient calculation Potential energy surfaces Combustion kinetic

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Synchronous construction of CoS2 in-situ loading and S doping for g-C3N4: Enhanced photocatalytic H2-evolution activity and mechanism insight

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CHEMICAL engineering JOURNAL 2020年 401卷 126135-126135页

作者： Zhang, Yazhou Shi, Jinwen Huang, Zhenxiong Guan, Xiangjiu Zong, Shichao Cheng, Cheng Zheng, Botong Guo, Liejin Xian Jiaotong Univ XJTU Int Res Ctr Renewable Energy IRCRE State Key Lab Multiphase Flow Power Engn MFPE 28 West Xianning Rd Xian 710049 Peoples R China Xiamen Univ Coll Chem & Chem Engn Collaborat Innovat Ctr Chem Energy MatState Key Natl & Local Joint Engn Res Ctr Preparat Technol 422 Siming South Rd Xiamen 361005 Peoples R China

Considering the fact of the cost control in photocatalysis, it is significant to develop the noble-metal-free photocatalysis for H-2 evolution. Herein, CoS2 in-situ loading and S doping for g-C3N4 were synchronously constructed by hydrothermal and sulfidation processes. With systematical physicochemical characterizations, it was found that partial N atoms in g-C3N4 were replaced by S atoms, improving the visible-light absorption ability for more generation of photo-generated carriers. CoS2 as an effective noble-metal-free H-2-evolution cocatalyst induced and captured photo-generated electrons for promoting separation of photo-generated carriers synergistically with S doping. More contact between CoS2 and g-C3N4 were formed by the in-situ growth of CoS2 nanosheets on the surface of g-C3N4 nanosheets. It was important that Co-S bonding between CoS2 and S-doped g-C3N4 was built by the synchronous construction of CoS2 in-situ loading and S doping, strengthening the directed transfer of photo-generated electrons from S-doped g-C3N4 to CoS2. Accordingly, the synergetic function of CoS2 in-situ loading and S doping effectively elevated the noble-metal-free photocatalytic activity of g-C3N4 for H-2 evolution under visible-light irradiation.

关键词： Photocatalysis Hydrogen Graphitic carbon nitride Cobalt disul fide Co-S bonding

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CFD simulation on the flow characteristics in the PWR lower plenum with different internal structures

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NUCLEAR engineering AND DESIGN 2020年 364卷 110705-110705页

作者： Wang, Mingjun Wang, Lianfa Wang, Xingjun Ge, Jian Tian, Wenxi Qiu, Suizheng Su, G. H. Xi An Jiao Tong Univ Dept Nucl Sci & Technol State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

The detailed thermal-hydraulic phenomena inside the lower plenum of Reactor Pressure Vessel (RPV) in Pressurized Water Reactor (PWR) affect the mass flow rate distributions at core inlet significantly, leading to an impact on the operation safety of nuclear reactors. From the engineering point of view, a homogeneous flow rate distribution at the core inlet is expected. Actually, series of design concepts of lower plenum internal structures were proposed for different PWRs in the world. In this paper, the three-dimensional CFD simulations with three types of internal structures in the lower plenum, TYPE 1 (Vortex suppression plate with the secondary supports), TYPE 2 (flow distribution skirt board with square coolant holes), TYPE 3 (Ellipsoid perforated drums and supports), were performed. The influence of different internal structures on the flow characteristics in the lower plenum were achieved and analyzed. The three types of internal structures were adapted into the same experimental facility “BORA”, which is a 1/5th scale 4-loops mock-up model, to realize the single variable criterion and obtain a uniform standard during the comparison. Results indicate that the mass flow rates in central fuel assemblies are much higher than that in peripheral fuel assemblies at core inlets with TYPE 1 and TYPE 2 internal structures, while the core inlet mass flow rate distribution with TYPE 3 internal structure is more homogeneous. This research has high reference value for the future advanced PWR lower plenum internal structures optimization and design.

关键词： PWR Lower plenum Internal structures flow rate distribution CFD

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Thermal-mechanical coupling behavior analysis of solid-state constrained component in advanced nuclear energy system

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Energy 2025年 330卷

作者： Xuan Yang Quan Li Jing Zhang Yingwei Wu Yanan He Chenxi Li Mingjun Wang Kailun Guo Chenglong Wang G.H. Su Wenxi Tian Suizheng Qiu State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an 710049 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu 610213 China

With the advantage of phase change heat transfer, heat pipes have the potential to replace flowing coolants for removing fission heat from nuclear reactors. However, the solid-state constrained heat transfer configuration poses mutual constraints between mechanical properties and heat transfer, and their long-term thermal-mechanical coupling behavior requires further investigation. Currently, research on long-term behavior is limited to either individual/local system components or a single physical field. In this paper, an analysis method for coupled thermal-mechanical behavior is proposed and verified, comprehensively considering thermal-mechanical properties, interactions between components, and the fission gas release. This method is employed to analyze the operating characteristics of a solid-state constrained component. The results indicate that prolonged operation leads to complete contact between structural components, generating high contact pressure that enhances heat transfer but increases creep. The release of gaseous fission products, accumulated over operating time, results in a synchronous increase in both gap and external contact pressures, reaching 5.2 MPa and 4.8 MPa, respectively. This process reduces the gas gap conductance, leading to elevated system peak temperatures and a reduction in temperature safety margins by 43 K. After heat pipe failure, continued operation significantly increases the local creep strain, up to 3.9 times that under normal conditions. The gap size and fuel gap pressure should be optimized to enhance gap heat transfer and reduce component creep. Excessive fission gas release should be avoided in fuel configuration. Reducing the system power following a single heat pipe failure can mitigate component creep and extend the operational lifespan.

关键词： Electric heating

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Ab initio study of metal carbide hydrides in the 2.25Cr1Mo0.25V steel

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PHYSICAL CHEMISTRY CHEMICAL PHYSICS 2021年第9期23卷 5199-5206页

作者： He, Min Onwudinanti, Chidozie Zheng, Yaoting Wu, Xiaomei Zhang, Zaoxiao Tao, Shuxia Xi An Jiao Tong Univ Sch Chem Engn & Technol State Key Lab Multiphase Flow Power Engn 28 Xianning West Rd Xian 710049 Shaanxi Peoples R China DIFFER Dutch Inst Fundamental Energy Res Ctr Computat Energy Res De Zaale 20 NL-5612 AJ Eindhoven Netherlands Xian Univ Architecture & Technol Sch Sci 13 Yanta Rd Xian 710055 Shaanxi Peoples R China Eindhoven Univ Technol Ctr Computat Energy Res Dept Appl Phys POB 513 NL-5600 MB Eindhoven Netherlands

2.25Cr1Mo0.25V is a state-of the-art alloy used in the fabrication of modern hydrogenation reactors. Compared to the conventional 2.25Cr1Mo steel, the 2.25Cr1Mo0.25V steel exhibits a better performance, in particular higher hydrogen damage resistance. Previous experimental studies indicate that carbides in steels may be responsible for the hydrogen-induced damage. To gain a better understanding of the mechanism of such damage, it is essential to study hydrogen uptake in metal carbides. In this study, Density Functional Theory (DFT) is used to investigate the stability of chromium, molybdenum and vanadium carbides (CrxCy, MoxCy and VxCy) in the 2.25Cr1Mo0.25V steel. The stability of their corresponding interstitial hydrides was also explored. The results showed that Cr7C3, Mo2C and V6C5 are the most stable carbides in their respective metal-carbon (Cr-C, Mo-C and V-C) binary systems. Specifically, V6C5 shows the strongest hydrogen absorption ability because of its strong V-H and C-H ionic bonds. On the other hand, V4C3, whose presence in the alloy was established in experimental studies, is predicted to be stable as well, along with V6C5. Our findings indicate that the hydrogen absorption ability of V4C3 is higher than that of V6C5. Additionally, the charge and chemical bonding analyses reveal that the stability of the metal carbide hydrides strongly depends on the electronegativity of the metal. Due to the high electronegativity of V, vanadium carbides form the strongest ionic bonds with hydrogen, compared to those of Mo and Cr. The results from this study suggest that the unique capacity of accommodating hydrogen in the vanadium carbides plays an important role in improved hydrogen damage resistance of the 2.25Cr1Mo0.25V alloy in hydrogenation reactors.

关键词： Hydrides

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EXPERIMENTAL INVESTIGATION ON HEAT TRANSFER CHARACTERISTICS OF SMOOTH WATER WALL TUBE OF AN ULTRA-SUPERCRITICAL CFB BOILER

EXPERIMENTAL INVESTIGATION ON HEAT TRANSFER CHARACTERISTICS ...

引用

ASMEInternational Mechanical engineering Congress and Exposition (IMECE2018)

作者： Wang, Wenyu Liang, Ziyu Wan, Li Liu, Dan Yang, Dong Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian Shaanxi Peoples R China

ISBN: (纸本)9780791852118

In this study, an experimental investigation was carried out to explore the heat transfer characteristics of the smooth water wall tube of an ultra-supercritical circulating fluidized bed (CFB) boiler. The ranges of the test pressure, mass flux, and heat flux were 23-32 MPa, 550-1200 kg.m(-2)-s(-1), and 200-560 kW.m(-2), respectively. The material of the tube used in the test was 12 Gr1MoVg. The diameter and wall thickness were 30 and 5.5 mm, respectively. The length of the test section was 2 m. The effects of the pressure, mass flux, heat flux, buoyancy, and flow acceleration on the heat transfer characteristics were analyzed. The formulas of the heat transfer coefficient were fitted, and the existing classical formula was used to evaluate the experimental data. The mechanism of heat transfer enhancement and deterioration of the tube were also investigated. Results showed that at the area of supercritical pressure, the wall temperature gradually increased with the increase of enthalpy in the pseudo-enthalpy region and sharply increased with the increase of enthalpy in the low-enthalpy region (enthalpy<1200 kJ kg(-1)) and high-enthalpy region (enthalpy>2400 kJ kg(-)1). This phenomenon indicated that heat transfer enhancement occurs near a pseudo-critical point. The increase of heat flux resulted in rapid heat transfer deterioration. Thereafter, the wall temperature rose immediately. The deterioration was delayed with the increase of mass flux and pressure. The effect of buoyancy and flow acceleration on the heat transfer concentrated on the pseudo-critical temperature of the fluid. Among the five selected heat transfer correlations, the Jackson and Bishop correlations agreed well with the experimental data.

关键词： Heat transfer Boilers Water

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The influence of morphological distribution of melanin on parameter selection in laser thermotherapy for vascular skin diseases

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LASERS IN MEDICAL SCIENCE 2020年第4期35卷 901-917页

作者： Ying, Z. X. Zhao, Y. B. Li, D. Shang, Y. L. Chen, B. Jia, W. C. Xi An Jiao Tong Univ Hosp 2 Dept Dermatol Xian 710004 Shaanxi Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710069 Shaanxi Peoples R China Univ Calif Irvine Beckman Laser Inst & Med Clin Irvine CA 92697 USA

Port wine stains (PWSs) are congenital vascular malformations that progressively darken and thicken with age. Currently, laser therapy is the most effective way in clinical management of PWS. It is known that skin pigmentation (melanin content) affects the radiant exposure that can be safely applied to treat PWS. However, the effect of melanin distribution in the epidermis on the maximum safe radiant exposure has not been studied previously. In this study, 10 different morphological distributions of melanin were proposed according to the formation and migration characteristics of melanin, and the two-scale heat transfer model was employed to investigate the influence of melanin distribution on the threshold radiant exposure of epidermis and blood vessels. The results show that melanin distributions do have a strong effect on laser parameter selection. When uniform melanin distribution is assumed, the threshold radiant exposure to damage a typical PWS blood vessel (50 mu m diameter) is 8.62 J/cm(2) lower than that to injure epidermis. The optimal pulse duration is 1-5 ms for a typical PWS blood vessel of 50 mu m when melanin distribution is taken into consideration. PWS blood vessels covered by non-uniformly distributed melanin are more likely to have poor response to laser treatment.

关键词： Port wine stains Melanin distribution Laser treatment Two-scale model Cryogen spray cooling

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Fluoride-Salt-Cooled High-Temperature Reactor: An Integrated Nuclear-Based Energy Production and Conversion System

SSRN

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SSRN 2023年

作者： Zhang, Dalin Li, Xinyu Jiang, Dianqiang Zhou, Xingguang Lv, Xindi Yun, Shichang Wu, Wenqiang He, Xuanang Li, Haoyang Min, Xin Chen, Kailong Tian, Wenxi Qiu, Suizheng Su, G.H. Zhao, Quanbin Fu, Yao Tang, Chuntao Zhuo, Wenbin Li, Jinggang Zuo, Jiaxu State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai201800 China Shanghai Nuclear Engineering Research & Design Institute CO. LTD. Shanghai200233 China CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology Nuclear Power Institute of China Chengdu610213 China China Nuclear Power Technology Research Institute Guangdong Shenzhen518000 China Nuclear and Radiation Safety Center Ministry of Ecology and Environment People's Republic of China Beijing100082 China

Based on the analysis of energy structure and the development trends of advanced nuclear energy technology, combining the complementary advantages of nuclear energy and other energy sources in China, the Fluoride-salt-cooled High-temperature Reactor(FuSTAR) system has been proposed. FuSTAR system is designed to address production capacity issues in areas with energy shortages or resource concentration and can be combined with high-temperature process heat to achieve high-value-added processes such as hydrogen production. In this paper, the Tri-structural isotropic fuel combined with helical cruciform elements has been studied in detail on the neutron physics and thermal-hydraulic properties, and the flow and heat transfer experiment is carried out for the first time. The multilayer nonlinear programming method has been applied to the design of thermal transport systems. Then the optimal parameters and configuration of the thermoelectric conversion system are obtained by the superstructure optimization method. The inherent safety of FuSTAR is demonstrated through deterministic safety analysis. In addition, the iodine-sulfur cycle technology and the characteristics of tritium production are also analyzed. This study highlights the significant potential of integrating nuclear energy with other energy sources in an optimized energy-production system. © 2023, The Authors. All rights reserved.

关键词： Nonlinear programming

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